eng. coste ioan dumitru study of protein and oil … · 2011. 10. 21. · eng. coste ioan dumitru...

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UNIVERSITY OF AGRICULTURAL SCIENCE AND VETERINARY MEDICINE CLUJ-NAPOCA DOCTORAL SCHOOL FACULTY OF AGRICULTURE Eng. COSTE IOAN DUMITRU STUDY OF PROTEIN AND OIL CONTENT VARIABILITY IN A SERIES OF LOCAL AND SYNTHETIC POPULATIONS, INBRED LINES AND HYBRIDS OF MAIZE (SUMMARY OF THE PhD THESIS) SCIENTIFIC ADVISOR PROF. DR. IOAN HAŞ CLUJ-NAPOCA 2011

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  • UNIVERSITY OF AGRICULTURAL

    SCIENCE AND VETERINARY MEDICINE

    CLUJ-NAPOCA

    DOCTORAL SCHOOL

    FACULTY OF AGRICULTURE

    Eng. COSTE IOAN DUMITRU

    STUDY OF PROTEIN AND OIL CONTENT VARIABILITY IN A SERIES OF

    LOCAL AND SYNTHETIC POPULATIONS, INBRED

    LINES AND HYBRIDS OF MAIZE

    (SUMMARY OF THE PhD THESIS)

    SCIENTIFIC ADVISOR

    PROF. DR. IOAN HAŞ

    CLUJ-NAPOCA

    2011

  • 2

    TABLE OF CONTENTS INTRODUCTION ...................................................................................................................... 9-5 CHAPTER I.............................................................................................................................. 11-7 IMPORTANCE OF MAIZE.................................................................................................... 11-7

    1.1. ECONOMIC IMPORTANCE .......................................................................................... 11-7 1.2. WORLDWIDE SPREAD................................................................................................. 13-8 1.3. WOLDWIDE MAIZE YIELD.......................................................................................... 14-8 1.4. MAIZE CULTIVATED AREAS AND YIELD IN ROMANIA......................................... 16-8 1.5. MAIZE UTILIZATION ...................................................................................................... 19 1.6. SPECIFIC UTILIZATION OF PROTEIN AND OIL FROM MAIZE .................................. 21

    CHAPTER II ................................................................................................................................22 GENETICS AND IMPROVEMENT OF OIL CONTENT ........................................................22

    2.1. INHERITANCE OF OIL CONCENTRATION IN MAIZE.................................................. 22 2.2. ASSOCIATION OF OIL CONTENT WITH OTHER AGRONOMIC TRAITS ................... 23 2.3. HIGH-OIL MAIZE BREEDING PROGRAMS ................................................................... 24 2.4. ENVIRONMENTAL EFFECTS ON MAIZE OIL CONTENT ............................................ 26 2.5. XENIA EFFECTS ON OIL CONTENT............................................................................... 27 2.6. SELECTION PROGRESS FOR INCREASED OIL CONTENT IN MAIZE ........................ 28 2.7. SELECTION METHODS USED TO INCREASE OIL CONTENT IN MAZIE................... 29

    2.7.1. Phenotipic recurent selections for increased oil content ............................................... 29 2.7.2. Single kernel selection for increased oil content. .......................................................... 30 2.7.3. Intensive selection for increased oil content ................................................................. 31 2.7.4. Modified phenotipic recurent selection for increased oil content .................................. 32

    2.8. FACTORS THAT CONTROL OIL QUALITY IN MAIZE HYBRIDS................................ 33 2.8.1. Factors that affect oilty acid composition of maize oil .................................................. 36 2.8.2. Inheritance of fatty acid compositon in maize ............................................................... 38

    2.9. VITAMIN E OR TOCOPHEROL ....................................................................................... 42 2.9.1. Genetic variability........................................................................................................ 42

    CHAPTER III...............................................................................................................................44 GENETICS AND IMPROVEMENT OF PROTEIN QUALITY AND CONTENT IN MAIZE

    .......................................................................................................................................................44 3.1. BIOCHEMICAL CHARACTERIZATION AND GENETIC BASE OF PROTEIN CONTENT IN MAIZE ................................................................................................................................. 45

    3.1.1. Mutant genes for protein quality................................................................................... 45 3.1.2. Inheritance of protein quality and content .................................................................... 47 3.1.3. Pleiotropic effects of mutant genes for protein quality .................................................. 48

    3.2. GERMPLASM FOR PROTEIN QUALITY AND CONTENT IMPROVEMENT................ 49 3.3. DEVELOPMENT OF MAIZE TYPES RICH IN SUPERIOR QUALITY PROTEINS......... 52

    3.3.1. Problemes of opaque-2 maize....................................................................................... 55 3.3.2. Breeding maize types with hard endosperm rich in essential aminoacids...................... 59

    3.4. STRUCTURE AND IMPORTANCE OF ZEIN FROM MAIZE PROTEIN ......................... 66 3.4.1. Descovery of protein bodies ......................................................................................... 66

  • 3

    3.4.2. Origin of prolaminic and globulinic protein bodies ...................................................... 68

    CHAPTER IV........................................................................................................................... 71-9 BIOLOGIC MATERIAL AND RESEARCH METHODS.................................................... 71-9

    4.1. BIOLOGIC MATERIAL ................................................................................................. 71-9 4.2. PREPEARING THE MATERIAL FOR CHEMICAL ANALYSIS ...................................... 72 4.3. NIR INSTALAB 600 ANALIZER....................................................................................... 73 4.4. NATURAL CONDITIONS OF THE EXPERIMENTAL SITE............................................ 75 4.5. STATISTICAL ANALYSES OF THE RESULTS............................................................... 80 4.6. OBSERVATIONS, NOTES AND DETEMINATIONS....................................................... 82 4.7. OBJECTIVES................................................................................................................ 83-10

    CHAPTER V .......................................................................................................................... 84-12 RESULTS AND DISCUSSIONS ( I ) ................................................................................... 84-12

    5.1. PROTEIN AND OIL CONTENT IN THE COLLECTION OF LOCAL POPULATIONS OF MAIZE FROM ARDS TURDA ............................................................................................ 84-12 5.2. PROTEIN AND OIL CONTENT IN SYNTHETIC POPULATIONS OF MAIZE CREATED AT ARDS TURDA.................................................................................................................... 87 5.3. PROTEIN AND OIL CONTENT IN INBRED LINES CREATED AT ARDS TURDA .. 90-12 5.4. STUDY OF THE RELATIONS BETWEEN KERNEL CONSTITUENTS IN LOCAL POPULATIONS........................................................................................................................ 97 5.5. STUDY OF THE RELATIONS BETWEEN KERNEL CONSTITUENTS IN SYNTHETIC POPULATIONS.......................................................................................................................102 5.6. STUDY OF THE RELATIONS BETWEEN KERNEL CONSTITUENTS IN INBRED LINES........................................................................................................................................... 107-13 5.7. STUDY OF PROTEIN AND OIL CONTENT IN THE COLECTION OF INBRED LINES FROM ARDS TURDA DEPENDING ON KERNEL TYPE......................................................112

    5.7.1. Protein and oil conten in inbred lines depending on kernel type ..................................112 5.7.2. Study of the relations between kernel constituents depending on kernel type................119

    CHAPTER VI....................................................................................................................... 138-19 RESULTS AND DISCUSSIONS ( II ) ................................................................................. 138-19

    6.1. PROTEIN CONTENT IN ISONUCLEAR INBRED LINES IN A BALANCED GENETIC SYSTEM............................................................................................................................ 138-19 6.2. OIL CONTENT IN ISONUCLEAR INBRED LINES IN A BALANCED GENETIC SYSTEM............................................................................................................................ 139-20 6.3. PROTEIN CONTENT IN ISONUCLEAR INBRED LINES IN A UNBALANCED GENETIC SYSTEM(2009-2010)......................................................................................................... 142-22 6.4. OIL CONTENT IN ISONUCLEAR INBRED LINES IN A UNBALANCED GENETIC SYSTEM(2009-2010)......................................................................................................... 145-23

    CHAPTER VII ..................................................................................................................... 151-25 INHERITANCE OF AGRONOMIC AND QUALITY TRAITS OF KERNELS IN CERTAIN

    ISONUCLEAR INBRED LINE CROSSES ........................................................................ 151-25 7.1. GENETIC STUDY ON DETERMINISM OF EAR WEIGHT.............................................152

  • 4

    7.2. GENETIC STUDY ON DETERMINISM OF EAR LENGTH ...................................... 157-26 7.3. GENETIC STUDY ON DETERMINISM OF THE NUMBER OF ROWS PER EAR..........161 7.4. GENETIC STUDY ON DETERMINISM OF 1000 KERNELS WEIGHT...........................167 7.5. GENETIC STUDY ON DETERMINISM OF YIELD CAPACITY.....................................173 7.6. GENETIC STUDY ON DETERMINISM OF DRY MATTER CONTENT IN KERNELS..179 7.7. GENETIC STUDY ON THE FALLING RESISTANCE OF MAIZE STALKS...................185 7.8. GENETIC STUDY ON DETERMINISM OF PROTEIN AND OIL CONTENT IN SELF POLLINATED AND OPEN POLLINATED KERNELS .................................................... 190-28

    7.8.1. Variance of protein content ................................................................................... 190-28 7.8.2. Study on protein content inheritance ..................................................................... 193-30 7.8.3. Variance of oil content .......................................................................................... 205-32 7.8.4. Study on oil content inheritance ............................................................................ 209-33

    CHAPTER VIII.................................................................................................................... 222-35 STUDY ON PROTEIN AND OIL CONTENT INHERITANCE IN A DIALLEL SYSTEM

    TYPE P(P-1) ......................................................................................................................... 222-35 8.1. PROTEIN CONTENT IN SELF POLLINATED KERNELS ........................................ 223-36 8.2. PROTEIN CONTENT IN OPEN POLLINATED KERNELS .............................................227 8.3. OIL CONTENT IN SELF POLLINATED KERNELS ................................................. 230-40 8.4. OIL CONTENT IN OPEN POLLINATED KERNELS.......................................................233

    CHAPTER IX....................................................................................................................... 237-43 CONCLUSIONS AND RECOMMENDATIONS ............................................................... 237-43 BIBLIOGRAPHY ................................................................................................................ 243-46

  • 5

    INTRODUCTION

    Maize is one of the most important crops due to its high productivity and its multiple

    uses as a food source for humans, livestock feed and as raw material in various industries

    (VASILICĂ, 1991, quoted by MUNTEAN et all., 2008).

    Maize kernels are used in industry to obtain alcohol, starch, dextrin, glucose as well

    as other products like plastics, glue, acetone, dyes, etc. From the seed embryo a good quality

    dietetic oil can be extracted that prevents the accumulation of cholesterol in the blood

    (MUNTEAN et all., 2008)

    The study of the maize germoplasm from ARDS Turda was initiated in an effort to

    identify local and synthetic populations and inbred lines which have potential use in the

    improvement of protein and oil content in maize kernel. There were also studied a series of

    isonuclear lines to identify if the utilization of different types of cytoplasm affect protein and

    oil content.

    Experimentation was carried out for a period of two years (2009-2010) in the

    experimental field of the corn breeding laboratory from Turda, and the testing of isonuclear

    lines regarding yield capacity, dry matter content and falling resistance has been made in

    two years (2009-2010) and two locations. Some of the expenses were sustained from a PN

    II-52-129/2008 project, developed in collaboration of UASVM Cluj-Napoca and ARDS

    Turda.

    The present thesis is structured in nine chapters and contains 254 pages, 103 tables,

    76 figures, 24 conclusions, 5 recommendations and 155 bibliographical titles were quoted

    from the scientific literature.

    The completion of this thesis, witch concludes a milestone in my professional

    training, would not have been possible without the help of some dear and wonderful people.

    Using this occasion I would like to thank them.

    I wish to express my gratitude to the scientific advisor, Mr. Prof. Dr. Ioan Haş, for his

    patience, guidance, professional training and constant attention during the years of my PhD

    preparation.

  • 6

    I would also like to thank Mrs. Dr. eng. Voichiţa Haş, head of the Corn Breeding

    Laboratory from ARDS Turda for her support given in order to carry out my experiments. I

    thank the entire staff of the Corn Breeding Laboratory from ARDS Turda, who contributed

    to my professional training and gave me their support to carry out my experiments

    I thank my colleagues from the Department of Genetics and Plant Breeding, for their

    friendship and support given in these three years spent together.

    Special thanks and gratitude to my family, I want to thank my wife for here patience

    and understanding, moral support given throughout my PhD training.

    Special thanks to the leadership of the University of Agricultural Sciences and

    Veterinary Medicine, Doctoral School, who contributed to my professional training.

    .

    Thank you!

  • 7

    CHAPTER I

    IMPORTANCE OF MAIZE

    1.1. ECONOMIC IMPORTANCE

    On a worldwide scale maize is situated on the third place concerning cultivated area

    (MUNTEAN et all., 2001; CRISTEA, 2004) and in first place concerning yield

    capacity(TROYER, 2006). Maize is also a valuable raw material for industry: from its kernels

    there can be extracted oil, starch, alcohol, glucose and other products such as syrup, pectin,

    dextrin, plastics, lactic acid, acetic acid, acetone, dyes, synthetic rubber etc. Maize stalk can be

    used to produce paper, cardboard, nitrocellulose (CRISTEA, 2004; ŞTEFAN, 2004).

    About one fifth of world maize production is used directly for human consumption.

    The tendency to reduce direct consumption of maize in human diet is more obvious in

    developed countries, where its ratio represents only 6.8%, while in developing countries is

    60% (CRISTEA, 2004).

    In addition to traditional uses, the overproduction of maize in the U.S. has led to its

    use in the production of bioethanol, maize thus becoming one of the plants that will

    contribute to saving fossil fuels and maintaining a cleaner environment (HAŞ, 2004).

    The world's corn production is used mostly for animal feed (72%) and current trends

    indicate that this share will increase. Regarding this manner of use we can observe the

    differences between developed and developing countries. The developed countries use about

    88% of the maize production for animal fodder, in the developing countries it represents

    only 27.9%. In these countries the situation is better in terms of maize use in food-

    processing industry. Currently, about 5% of world production of maize is used in industrial

    processing (CRISTEA, 2004).

  • 8

    1.2. WORLDWIDE SPREAD

    Corn is grown in various climatic and soil conditions, in the northern hemisphere in

    Canada and Russia up to 58 ° latitude, and in the southern hemisphere, in New Zealand, up

    to 42-43 degrees. Grown for grain, corn can be found between 42º and 53º northern latitude,

    this limit is exceeded when the destination use is as green fodder.

    1.3. WORLDWIDE MAIZE YIELD

    Due to more efficient application of technology and the use of heterosis phenomenon

    in creating new maize hybrids, in order to increase corn production its yield, in some

    countries reached a spectacular level (CRISTEA, 2004).

    Estimated by FAO, in 2004 total maize kernel production was about 724.589.004

    tons, and average global yield per hectare to 49.2 q / ha (FAO, 2004). The largest areas

    planted with maize were in America, followed by Asia, Africa and Europe.

    1.4. MAIZE CULTIVATED AREAS AND YIELD IN ROMANIA

    Regarding the evolution of maize production in Romania before 1960 the average yield

    per area unit was somewhere around 1000 kg. In this period different varieties and local

    populations were used. The introduction of double-cross hybrids, after 1960 provides a

    doubling of maize production

    After the Revolution in December 1989 due to new situations created by structural and

    functional reorganization of state institutions, and the transition to market economy,

    agriculture has undergone major transformations too, which unfortunately, didn’t have a

    favorable influence on agricultural yield, in all situations.

  • 9

    CHAPTER II

    BIOLOGIC MATERIAL AND RESEARCH METHODS

    2.1. BIOLOGIC MATERIAL A total of 422 inbred lines, 258 of local populations and 60 synthetic populations of

    maize were studied in terms of protein, oil, starch and fiber content. This collection of

    germplasm from ARDS Turda consists of material from its own breeding program and

    materials obtained from biological material exchange with other research centers.

    In addition to the 422 inbred lines, 258 local populations and 60 synthetic

    populations, five groups of isonucleare lines have been studied (in each group an elite inbred

    line and six sister lines on different types of cytoplasm) and were crossed with three testers

    for TC221, TB367, D105 group and four testers for the group TC209 and TC243 to make an

    experimental systems that enables the testing of the role of cytoplasm, testers and testers x

    cytoplasm interactions.

    The studied isonucleare lines (seven in each group) were obtained by transferring the

    nucleus on different types of cytoplasm using 10 backcrosses (Figure 1). It was considered

    that in this way the transfer was made to about 99.9%, the only difference between the

    isonuclear lines from the same group consisted in genetic factors situated in the cytoplasm

    and eventual interactions between the nuclear and cytoplasm factors.

    The isonuclear lines were created between 1992-2004 at ARDS Turda, starting from

    the assumption that between different sources of cytoplasm there could be differences

    regarding the genetic value. After this period the isonuclear lines were maintained by self

    pollination or using SIB pollination (CHICINAŞ et all., 2009).

  • 10

    Cytoplasm Nucleus donor donor

    I X 50.00 % II X 75.00 % III X

    87.50 % IV X 93.75 % V X

    96.88 % VI X 98.44 % VII X

    99.22 % VIII X 99.61 % IX X

    99.90 % X

    Fig. 1. Transferring method of the nucleus on to a new cytoplasm

    2.3. OBJECTIVES The objectives were as follows:

    study of the local population, synthetic population and inbred lines of maize from

    ARDS Turda regarding protein and oil content, and identification of correlations

    between the kernel constituents

    identification of the protein and oil rich/poor genotypes from the germplasm

    collection;

    study of the general and specific combining ability of the isonuclear inbred lines in

    crosses with elite tester inbred lines;

    to evidence the influence of cytoplasm on maize ear traits, protein and oil content,

    yield capacity, falling resistance and dry matter content;

  • 11

    identification of valuable types of cytoplasm that can be used in breeding programs to

    improve oil and protein content;

    to highlight the cytoplasm effects involved in the inheritance of protein and oil

    content using direct and reciprocal crosses.

  • 12

    CHAPTER III

    RESULTS AND DISCUTIONS (I)

    3.1. PROTEIN AND OIL CONTENT IN THE COLLECTION OF LOCAL POPULATIONS OF MAIZE FROM ARDS TURDA

    Statistical analysis of protein and oil content is presented in table 1. Mean protein

    content in local populations was 13.69% and oil content was 5.38%.

    Range for protein was 4.40% and 3.50% for oil content. Confidence level for the

    local populations was 0.10% for protein content and 0.08% for oil content.

    Table 1

    Statistical analysis of protein and oil content for a series of local maize populations Statistical parameters Protein Oil

    Mean % 13.69 5.38 Standard error 0.05 0.04 Standard deviation 0.84 0.63 Sample variance 0.70 0.39 Range 4.40 3.50 Minimum value 11.20 3.80 Maximum value 15.60 7.30 The coefficient of variation 6.12 11.6 Confidence level 95% 0.10 0.08 Number of cases 258 258

    3.2. PROTEIN AND OIL CONTENT IN INBRED LINES CREATED AT ARDS TURDA Statistical analysis of protein and oil content of the 422 inbred lines created at ARDS

    Turda is presented in table 2.

    Mean protein content is 13.43%, the range for protein content being 6.90%. Variance

    was relatively low (1.17%) and standard deviation was 1.08%, resulting that for a large

    number of inbred lines the deviation from the average was statistically significant.

    Mean oil content was 4.16%, sample variance was 0.75% and confidence level was

    0.08%. Oil content range has been between 2.40% and 7.60%.

  • 13

    Table 2

    Statistical analysis of protein and oil content for a series of inbred maize lines Statistical parameters Protein Oil

    Mean % 13.43 4.16 Standard error 0.05 0.04 Standard deviation 1.08 0.87 Sample variance 1.17 0.75 Range 6.90 5.20 Minimum value 10.80 2.40 Maximum value 17.70 7.60 The coefficient of variation 8.06 20.88 Confidence level 95% 0.10 0.08 Number of cases 422 422

    3.3. STUDY OF THE RELATIONS BETWEEN KERNEL CONSTITUENTS IN INBRED LINES

    Figure 2 presents the relationship between protein and oil content for the 422 inbred

    lines from the germplasm collection of maize from ARDS Turda. The correlation coefficient

    between protein content and oil content (r = 0.3866 **) indicate a distinctly significant

    positive relationship between the two characters. The relationship is described by the upward

    slope of the regression line b = 0.4816, analyzing the regression it can be seen that by

    increasing the oil content with a unit protein content increases by 0.48 units.

    The coefficient of determination (R2 = 0.1495) shows that in the case of the 422

    inbred lines of maize studied, the variation of protein content is determind in a share of 14%

    by the variation in oil content. Analyzing the distribution of inbred lines, two inbred lines

    with high protein and oil content were distingwished (TC106 with 16.4% protein and 7.5%

    oil, T442 15.6% protein and 7.2% oil) giving them potential use in breeding programs to

    improve protein and oil content.

    The correlation between protein and starch content (r =- 0.6263 **) shown in figure 3

    is dinsctincly significantlty negative and the coefficient of detemination (R2 = 0.3922) shows

    that the variation of protein content is determined in share of 39% by starch content

  • 14

    variation. Following the downward slope of the regression line (b = -0.2507) it can be seen

    that increasing the starch content with a uint causes a decrease in protein content with 0.25

    units. From the analyzed inbred lines regarding the correlation between protein and starch

    content three inbred lines were highlighted because of high protein and starch content T397

    (16% protein and 65.4% starch), TC350 (15.7% proteins and 66.6% starch) and TC245

    (15.7% protein and 66.3% starch).

    In case of the correlation between protein and fiber content shown in figure 4 (r =

    0.6748 **) there can be identified a distinctly significant positive correlation, with an

    upward slope of the regression line (b = 0.7931), and it can be that increasing the fiber

    content with a unit protein content is increased with 0.79 units. Analyzing the relation

    between protein and fiber content it can be concluded that inbred lines T139 (17.7% protein

    and 7.1% fiber), TC106 (16.4% protein and 7.1% fiber) and TB370 (16% 6.9 protein and

    fiber) can be used in maize breeding programs for high protein and fiber content.

    0

    2

    4

    6

    8

    10

    12

    14

    16

    18

    20

    2 3 4 5 6 7 8

    oil(%)

    port

    ein(

    %)

    r = 0.3866**

    R2= 0.1495

    y = 11.4215+0.4816x

    n = 422

    Fig. 2. Relation between protein and oil content in inbred maize lines

  • 15

    0

    2

    4

    6

    8

    10

    12

    14

    16

    18

    20

    40 45 50 55 60 65 70 75

    starch(%)

    prot

    ein(

    %)

    r = -0.6263**

    R2= 0.3922y = 30.3619-0.2507x

    n = 422

    Fig. 3. Relation between protein and starch content in inbred maize lines

    0

    2

    4

    6

    8

    10

    12

    14

    16

    18

    20

    2 3 4 5 6 7 8

    fiber(%)

    port

    ein(

    %)

    r = 0.6748**

    R2= 0.4553

    y = 9.5555+0.7931x

    n = 422

    Fig. 4. Relation between protein and fiber content in inbred maize lines

  • 16

    0

    1

    2

    3

    4

    5

    6

    7

    8

    7 9 11 13 15 17 19

    protein(%)

    oil(%

    )

    r = 0.3866**

    R2= 0.1495

    y = -0.006+0.3104x

    n = 422

    Fig. 5. Relation between oil and protein content in inbred maize lines

    0

    1

    2

    3

    4

    5

    6

    7

    8

    40 45 50 55 60 65 70 75

    starch(%)

    oil(%

    )

    r = -0.8454**

    R2= 0.7147

    y = 22.5164-0.2717x

    n = 422

    Fig. 6. Relation between oil and starch content in inbred maize lines

  • 17

    0

    1

    2

    3

    4

    5

    6

    7

    8

    2 3 4 5 6 7 8

    fiber%)

    oil(%

    )

    r = 0.6579**

    R2= 0.4329

    y = 1.1315+0.6208x

    n = 422

    Fig. 7. Relation between oil and fiber content in inbred maize lines

    Figure 5 shows the relationship between oil and protein content. Correlation

    coefficient value, r = 0.3866 ** indicates a distinctly significant positive relationship

    between the studied characters. The relationship between these constituents of the maize

    kernel is described by an upward regression slope b = 0.3104, expressing a close relationship

    between oil and protein content, thus increasing protein content with a unit increases oil

    content with 0.31 units. The coefficient of determination R2 = 0.1495 shows that the

    variation of oil content is determined at a rate of 14% by variation in protein content. Inbred

    lines that are recommended to be used in breeding programs to improve oil and protein

    content are TC106 (7.5% oil and 16.4 protein) and T442 (7.2% oil and 15.6% protein).

    The correlation between oil and starch content (r =- 0.8454 **) shown in figure 6 is

    distinctly significantly negative and oil content variation is determined in 71% by the

    variation of starch content. Following the downward slope of the regression line (b = -

    0.2717) it can be seen that increasing the starch content with a unit causes a decrease in oil

    content by 0.27 units. Based on analysis of regressions two inbred lines have been identified

    (TC344 6.2% oil and 65.1% starch, 5.9% TC346 65.3% oil and starch) with high oil and

    starch content.

  • 18

    In case of the correlation between oil and fiber content shown in figure 7 (r = 0.6579

    **) we can identify a distinclty significant positive correlation with an upward slope of the

    regression line (b = 0.6208), and it can be observed that increasing the fiber content with a

    unit oil content increases by 0.62 units. Analyzing the oil content according to fiber content

    it can be observed that inbred lines TC344 (7.5% oil and 7.5% fiber), TC344A (7.6% oil and

    7.2% fiber), TC106 (7, 5% oil and 7.1% fiber) and TC375 (7.1% oil and 7.3% fiber) can be

    used in breeding programs to increase oil and fiber content.

  • 19

    CHAPTER IV

    RESULTS AND DISCUTIONS (II)

    4.1. PROTEIN CONTENT IN ISONUCLEAR INBRED LINES IN A BALANCED GENETIC SYSTEM

    Table 3 shows the protein content in five groups of isonuclear maize lines. The mean

    protein content of the five groups of isonuclear lines was 12.86%, the highest protein content

    being recorded for group D105 with cit.TB329 (14.47%) while the lowest for the group of

    lines TC316 with cit.TC221 (11.53%). Out of the cytoplasm’s that were used to improve the

    protein content only cit.T248 showed positive deviation from conventional cytoplasm in

    four of the five groups of isonuclare lines. Using cytoplasm from TC221 the protein content

    decreased with 0.29% presenting a distinctly significant negative difference.

    Table 3

    Protein content of five groups of isonuclear inbred maize lines in a balanced genetic system (ARDS Turda, 2010)

    Nucleus Cytoplasm TC209

    % TC316

    % TC243

    % TB367

    % D105

    %

    Mean for each type of

    cytoplasm

    Deviation+/-from conventional

    cytoplasm

    Conventional 12.23 12.40 12.87 13.33 13.63 12.89 0.00 cit.T248 13.13*** 12.83* 13.90*** 12.13ooo 13.80 13.16 +0.27**

    cit.TB329 13.07*** 11.83oo 12.93 12.13ooo 14.47*** 12.89 0.00 cit.TC177 12.67* 13.23*** 12.13ooo 12.37ooo 13.47 12.77 -0.12 cit.TC221 12.30 11.53ooo 13.60*** 13.07 12.50ooo 12.60 -0.29oo

    Mean of isonuclear lines 12.68 12.37oo 13.09 12.61 13.57*** 12.86

    LDS comparisons C P 5% = 0.17 P 1% = 0.23 P 0.1% = 0.30

    LDS comparisons N P 5% = 0.28 P 1% = 0.41 P 0.1% = 0.62

    LDS comparisons C×N P 5% = 0.39 P 1% = 0.52 P 0.1% = 0.68

    From the five groups of isonucleare lines, the highest mean protein content was

    registered for the lines generated by the D105. Specific interactions were noted between the

    type of cytoplasm and nucleus. The inbred lines TC209 (cit. T248), TC209 (cit.TB329),

    TC209 (cit.TC177), TC316 (cit.T248), TC316 (cit.TC177), TC243 (cit.T248), TC243

  • 20

    (cit.T221) , D105 (cit. TB329) exceeded with statistically significant values the protein

    content of lines supplying the nucleus, while for the lines TC316 (cit.TC221), TC316

    (cit.TB329), TC243 (cit.TC177), TB367 (cit.T248), TB367 (cit.TB329), TB367 (cit.TC177)

    and D105 (cit.TC221) protein content was significantly lower than that of lines that supplied

    the nucleus.

    4.2. OIL CONTENT IN ISONUCLEAR INBRED LINES IN A BALANCED GENETIC SYSTEM

    Oil content of maize kernels of a system of inbred lines with five types of cytoplasm

    is shown in table 4. Experimental system average was 4.92%, the highest values of oil content were recorded in the group of isonucleare lines TB367 (6.45%), followed by the

    group of isonucleare lines TC243 (5.25%).

    Table 4

    Oil content of five groups of isonuclear inbred maize lines in a balanced genetic system (ARDS Turda, 2010)

    Nucleus Cytoplasm

    TC209 %

    TC316 %

    TC243 %

    TB367 %

    D105 %

    Mean for each type of cytoplasm

    Deviation+/- from

    conventional cytoplasm

    Conventional 4.00 3.90 5.37 6.07 4.73 4.81 0.00

    cit.T248 4.60** 3.90 5.20 5.83 4.87 4.88 +0.07 cit.TB329 3.67 4.07 5.33 6.57* 4.70 4.87 +0.05 cit.TC177 4.37 3.80 5.43 7.30*** 4.70 5.12 +0.31** cit.TC221 4.40 4.40* 4.93o 6.47 4.40 4.92 +0.11

    Mean of isonuclear lines

    4.21ooo 4.01ooo 5.25* 6.45*** 4.68o 4.92

    LDS comparisons C P 5% = 0.20 P 1% = 0.26 P 0.1% = 0.35

    LDS comparisons N P 5% = 0.23 P 1% = 0.33 P 0.1% = 0.50

    LDS comparisons C×N P 5% = 0.44 P 1% = 0.59 P 0.1% = 0.77

    Cytoplasm type had a higher influence on oil content in case of the cytoplasm from

    the inbred line TC177. Range of the oil content was between 3.67% for TC209 (cit. TB329)

    and 7.30% for TB367 (cit.TC177).

  • 21

    Favorable specific interactions between cytoplasm and nucleus were recorded for the

    following inbred lines: TC209 (cit.T248), TC316 (cit.TC221), TB367 (cit.TC177) and

    TB367 (cit.TB329). In one case, the transfer of the nucleus led to a significant decrease in

    oil content for the inbred line TC243 (cit.TC221).

    Table 5 Analysis of variance of the chemical composition of the maize kernel for five groups of

    inbred lines in a balanced genetic system (ARDS Turda, 2010) Protein Oil Cause of variability DF SP s2 SP s2

    Genotypes (G) 24 36.95 1.54** 64.39 2.68**

    Nucleus(N) (4) 13.50 3.37** 57.45 14.36**

    Cytoplasm(C) (4) 2.50 0.63** 0.84 0.21*

    Interaction N x C (16) 20.94 1.31** 6.10 0.38**

    Repetitions(R) 2 0.11 0.06 0.05 0.03

    Error N 8 0.91 0.11 0.58 0.07

    Error C 40 2.20 0.06 2.84 0.07 Total 74 40.18 67.86

    As it can be observed from table 5, the genetic factors of cytoplasm have a distinctly

    significant influence on variability of protein content (s2 = 0.63 **) and a significant

    influence on variability of oil content (s2 = 0.21 *). Nuclear factors have a distinctly

    significant influence on the variability of protein content (3.37 **) and oil content (14.36

    **). The nuclear-cytoplasm interactions have a distinctly significant influence on protein

    content variability (1.31 **) and significant influence on oil content variability (0.38 *).

    In figure 8 the share of genetic factors involved in protein and oil content variability

    is presented, the share of nuclear factors in the variability of protein content being 37% and

    89% for oil content variability. Regarding the influence of cytoplasm, the share was 7% for

    protein content variability and 1% for oil content variability. Nuclear-cytoplasm interactions

    had a 57% share in the variability in protein content and 10% in oil content variability.

  • 22

    1- nucleus; 2- cytoplasm; 3- nucleus-cytoplasm interaction

    Fig. 8. Contribution of nucleus, cytoplasm and interactions between nucleus and cytoplasm in the variance of protein and oil content of five groups of isonuclear inbred maize lines in a

    balanced genetic system (ARDS Turda, 2010)

    4.3. PROTEIN CONTENT IN ISONUCLEAR INBRED LINES IN A UNBALANCED GENETIC SYSTEM (2009-2010)

    The results of the analyses for protein content from self pollinated and open

    pollinated kernels between 2009-2010 in the group of isonuclear lines TC243 is shown in

    table 6.

    Average protein content of the two experimental years, for the self pollinated kernels

    was 12.63% with quite large differences between the two experimental years (13.49% in

    2009 and 11.79% in 2010). In the case of open pollinated kernels the average protein content

    of the two years was 11.41%, and the differences between the experiment years was lower

    (11.77% in 2009 and 11.05% in 2010).

    In comparison wih the control line TC243 that generated the group of isonuclear lines

    with a protein content of 11.64%, five isonucleare lines registered an increase in protein

    content TC243 (cit.T248), TC243 (cit.TC208), TC243 (cit.TC221), TC243 (cit.K1080) and

    TC243 (cit.K2051). Analysis of differences in the two types of pollinated material provided

    data that is statistically assured differences indicate that the protein rich isonucleare lines

    T248, TC208, TC221, K1080 and K2051 can be used to improve the protein content of the

    line TC243 that generated the group of isonuclear lines.

    Protein

    37%

    7%57%

    1 2 3

    Oil

    89%

    1% 10%

    1 2 3

  • 23

    Table 6

    Protein content of the tested isonuclear inbred maize lines TC243 in a unbalanced genetic system (ARDS Turda, 2009-2010)

    Protein content of maize kernel from self pollinated ears (%)

    Protein content of maize kernel from open pollinated ears (%)

    Mean for each cytoplasm (%)

    Isonuclear inbred line

    2009

    2010

    Mean % vs initial

    line

    2009 2010 Mean % vs initial

    line

    Mean content

    Relative

    value

    TC243(martor/control) 13.27 12.07 12.67 100.0 11.93 9.27 10.60 100.0 11.64 100.0 TC243(cit. A665) 13.30 11.77 12.54 98.9 10.77 9.27 10.02 94.5 11.28 96.9 TC243(cit.T248) 14.20 12.27 13.24*** 104.5 11.27 11.30 11.29*** 106.5 12.26 105.4 TC243(cit.TC208) 12.93 11.90 12.42 98.0 12.17 11.73 11.95*** 112.7 12.18 104.7 TC243(cit.TC221) 13.47 11.87 12.67 100.0 12.00 11.23 11.62*** 109.6 12.14 104.4 TC243(cit.K1080) 14.07 10.93 12.50 98.7 11.83 12.13 11.98*** 113.0 12.24 105.2 TC243(cit.K2051) 13.20 11.53 12.37 97.6 12.40 12.43 12.42*** 117.1 12.39 106.5 Mean of isonuclear lines 13.49 11.76 12.63 11.77 11.05 11.41 12.02 LDS (P=5%) 0.32 0.26 LDS (P=1%) 0.43 0.35 LDS (P=0.1%) 0.55 0.45

    4.4. OIL CONTENT IN ISONUCLEAR INBRED LINES IN A UNBALANCED GENETIC SYSTEM (2009-2010)

    The results of the analysis for oil content in the group of isonucleare lines TB367 are

    shown in table 7. Mean oil content of this group of lines was the highest from the five

    groups of isonuclear lines studied.

    Compared to the control line TB367 that generated the group of isonuclear lines with

    an oil content of 5.60%, three isonucleare lines registered an increase in oil content TB367

    (cit.TC209), TB367 (cit.TC208) and TB367 (cit.TC221) and had the following amounts of

    oil content: 6.39%, 6.25%, 6.04%. These values allow us to say that these genotypes may be

    considered rich in oil content. Analysis of differences between the two types of pollination

    provided statistically assured results for the isonuclear lines with high oil content (COSTE et

    al., 2011).

  • 24

    Table 7 Oil content of the tested isonuclear inbred maize lines TB367 in an unbalanced genetic

    system (ARDS Turda, 2009-2010) Oil content of maize kernel from

    self pollinated ears (%) Oil content of maize kernel from

    open pollinated ears (%) Mean for each cytoplasm (%)

    Isonuclear inbred line

    2009

    2010

    Mean

    % vs initial

    line

    2009

    2010

    Mean %

    vs initial line

    Mean content

    Relative value

    TB367 (control) 6.13 5.70 5.92 100.0 5.83 4.73 5.28 100.0 5.60 100.0 TB367(cit.T248) 5.40 6.10 5.75 97.2 5.27 5.63 5.45 103.2 5.60 100.0 TB367(cit.TB329) 5.50 5.83 5.67 95.8 5.00 7.30 6.15*** 116.5 5.91 105.5 TB367(cit.TC208) 6.17 6.60 6.39 107.9 5.07 7.17 6.12*** 115.9 6.25 111.7 TB367(cit.TC221) 6.03 5.77 5.90 99.7 5.67 6.70 6.19*** 117.1 6.04 107.9 TB367(cit.TC209) 6.40 5.97 6.19 104.6 7.93 5.27 6.60*** 125.0 6.39 114.2 TB367(cit.K2051) 6.47 6.53 6.50* 109.9 5.60 5.07 5.34 101.0 5.92 105.7 Mean of isonuclear lines 6.01 6.07 6.04 5.77 5.98 5.87 5.96 LDS (P=5%) 0.48 0.49 LDS (P=1%) 0.64 0.65 DL (P=0.1%) LDS (P=0.1%) 0.83 0.84

  • 25

    CHAPTER V INHERITANCE OF AGRONOMIC AND QUALITY TRAITS OF KERNELS

    IN CERTAIN GROUPS OF ISONUCLEAR INBRED LINE CROSSES

    The literature indicates that most of the characters that help to increase yield in maize

    (ear size, ear length, number of rows of kernels per ear, number of kernels per row, 1000

    kernel weight) are genetically conditioned, in highest share at nuclear level, but there are

    allegations that in the inheritance of some of these characters genes with cytoplasm

    localization could be involved (HALLAUER and MIRANDA, 1981; CĂBULEA, 1975;

    CĂBULEA et all., 1981; STUBER and EDWARDS, 1986; STUBER et all., 1992; HAŞ,

    1992; CĂBULEA et all., 1994; CĂBULEA et all., 1999; TROYER, 2001; CĂBULEA,

    2004; SARCA, 2004; HAŞ,2004).

    The understanding of kernel quality determinism is important in combination with

    improving kernel production and other agronomic characteristics, but also for improvement

    of nutritional and industrial properties (POLLAK and SCOTT, 2005; OSORNO and

    CARENA, 2008). Increasing the nutritional value of maize grain is possible using

    technologic and genetic methods (HAŞ et all., 2004; HEGYI et all., 2007; HEGYI et

    all.,2008; IDIKUT et all., 2009).

    Yield capacity can be considered the most complex trait from genetic point of view.

    Due to the considerable number of genes involved, and gene interactions, the heterozygous

    state, as well as the complex interactions with environmental factors, make yield capacity

    one of the most difficult targets as a genetic study and is one of the traits with the lowest

    heritability (HALLAUER and MIRANDA, 1981).

    Genetic determinism of protein and zein content is significantly correlated at an

    additive genetic level and is controlled by additive gene and cytoplasm actions (CĂBULEA

    and ZETEA, 1973) or only by gene interactions (CĂBULEA et al., 1984).

    Given the importance of embryo size in the improvement of oil content, the oil

    content is related to kernel size and hence in the inheritance of oil content cytoplasm actions

    are involved (ALEXANDER and CREECH, 1977; COSMIN et al., 1993; SARCA et al.,

    1995).

  • 26

    5.1. GENETIC STUDY ON DETERMINISM OF EAR LENGTH Analysis of variance for ear length for the five groups of isonucleare maize lines that

    were tested is presented in table 8. Variance for the influence of experimental years was

    distinctly significant for the group of isonuclear lines TC209 and TC243 and significant for

    TC221 and TB367, revealing the importance of climatic conditions in the manifestation of

    this character.

    Table 8 Analysis of variance of ear length for the tested isonuclear inbred maize lines

    (ARDS Turda, 2009-2010) Isonuclear line

    TC209 Isonuclear line

    TC243 Isonuclear line

    TC221 Isonuclear line

    TB367 Isonuclear line

    D105 Cause of variability DF

    SP s2 SP s2

    DF

    SP s2 SP s2 SP s2

    Experimental years (Y) 1 192.71 192.71** 84.86 84.86* 1 60.32 60.32* 19.06 19.06* 0.00 0.00

    Genotype 27 211.51 7.83** 333.65 12.36** 20 48.19 2.41* 17.09 0.85* 30.03 1.50**

    Cytoplasm (C) (6) 67.85 11.31** 4.24 0.71 (6) 13.17 2.20* 3.71 0.62 3.79 0.63

    Tester (T) (3) 117.65 39.22** 305.89 101.96** (2) 17.83 8.91 5.92 2.96 14.91 7.46**

    (C×T) interaction (18) 26.01 1.45** 23.52 1.31** (12) 17.19 1.43 7.46 0.62 11.33 0.94**

    (Y×T) interaction 3 13.08 4.36** 8.30 2.77* 2 3.53 1.77 7.49 3.74* 2.24 1.12**

    (Y×C) interaction 6 21.85 3.64** 12.31 2.05** 6 12.05 2.01 7.61 1.27* 2.18 0.36

    (Y×T×C) interaction 18 23.89 1.33* 12.45 0.69 12 23.61 1.97* 8.18 0.68 4.38 0.37

    Repetition ( R ) 2 5.28 2.64 5.19 2.60 2 8.45 4.23 0.21 0.11 1.93 0.97

    Error Y 2 2.04 1.02 1.85 0.93 2 2.60 1.30 1.32 0.66 1.34 0.67

    Error T 12 5.88 0.49 9.20 0.77 8 19.92 2.49 7.10 0.89 0.64 0.08

    Error C 96 59.12 0.62 52.06 0.54 72 68.45 0.95 31.39 0.44 24.55 0.34

  • 27

    1- the share of cytoplasm effect variance;

    2 - the share tester effect variance; 3 the share "cytoplasm x tester" interaction effect variance Fig. 9. Share of each factor involved in the genetic variance of ear length for the five

    groups of isonuclear inbred lines that were tested

    Cytoplasm have provided statistically significant differences in two of the five groups

    tested, higher values of variance were recorded for testers, and for cytoplasm × tester

    interactions lower values were recorded but statistically significant.

    Share of the factors involved in ear length variance is presented in figure 9.

    Cytoplasm share ranged from 1% for the group of lines TC243 and 32% for the group of

    lines TC209, testers share was 35% for the group of lines TB367 and 92% for the group of

    lines TC243; "cytoplasm × testers" interactions had a share ranging between 7% in the group

    of lines TC243 and 43% in the group of lines TB367.

    The results of general and specific combining ability involved in the inheritance of

    ear length for the group of isonuclear lines TC209 is presented in table 9. Range of

    cytoplasm effects was between -0.69cm for TC209 and 0.82cm for TC209(cit.TC177), the

    general combining ability effects due to testers ranged between -0.52cm for TB329 and 1.45

    cm for Lo3Rf. Values of specific combining effects ranged between -0.9cm in the hybrid

    combination TC209 (cit.W633) × TC344 and 0.7cm for TC209 (cit.W633) × Lo3Rf.

    TC209

    32%

    56%

    12%

    1 2 3

    TC243

    1%

    92%

    7%

    1 2 3

    TC221

    27%

    37%

    36%

    1 2 3

    TB367

    22%

    35%

    43%

    1 2 3

    D105

    13%

    49%

    38%

    1 2 3

  • 28

    From the hybrid combinations the highest values for ear length obtained in the following hybrid combinations:

    - TC209(cit.W633)×Lo3Rf=21.3cm=μ(+18.4cm)+ĝcit(+0.73cm)+ĝtest(+1.45cm)+ŝcit

    × test(0.7cm)

    - TC209(cit.D105)×Lo3Rf=20.9cm=μ(+18.4cm)+ ĝcit(+0.62cm)+ ĝtest(+1.45cm)+ŝcit

    × test(0.5cm)

    In the inheritance of ear length for the hybrid combinations with the highest ear

    length are involved in addition to the mean effects, general combining ability effects due to

    testers followed by general combining ability of cytoplasm and specific combining ability.

    Table 9 General and specific combining ability involved in the inheritance of the ear length in the

    tested isonuclear inbred maize lines TC 209(ARDS Turda, 2009-2010) TC344 Lo3Rf TB329 TD233

    cytoplasm/tester cm ŝ cit x test cm ŝ cit x test cm ŝ cit x test cm ŝ cit x test

    x ĝcit

    TC209 18.0 0.7 18.6 -0.6 17.5 0.3 16.8 -0.4 17.7 -0.69 TC209(cit.A665) 17.5 0.2 19.2 -0.1 17.5 0.2 17.1 -0.2 17.8 -0.61 TC209(cit.T291) 17.1 -0.4 19.2 -0.3 17.7 0.2 18.1 0.5 18.0 -0.38 TC209(cit.T248) 17.5 0.1 19.1 -0.2 17.2 -0.2 17.9 0.4 17.9 -0.49 TC209(cit.W633) 17.8 -0.9 21.3 0.7 18.7 0.1 18.8 0.1 19.1 0.73 TC209(cit.TC177) 19.4 0.6 20.7 0.0 18.5 -0.2 18.4 -0.4 19.2 0.82 TC209(cit.D105) 18.3 -0.2 20.9 0.5 18.2 -0.3 18.7 0.1 19.0 0.62

    Mean for tester 17.9 19.9 17.9 18.0 18.4 0.00 ĝtest -0.48 1.45 -0.52 -0.45 18.4 0.00

    LDS 5% comparison ĝcytoplasm 0.45 LDS 5% comparison ĝtester 0.33 LDS 5% comparison for interaction c × t 0.90

    5.2. GENETIC STUDY ON DETERMINISM OF PROTEIN AND OIL CONTENT IN SELF POLLINATED AND OPEN POLLINATED KERNELS

    5.2.1. Variance of protein content

    Maize protein is less important than that of other grains due to high level of zein

    fraction, but it is hoped that this inconvenience will be eliminated; still it is desirable to have

    available forms with high protein content and better quality.

  • 29

    Analysis of variance in protein content for the five groups of isonuclear lines that

    were self pollinated is presented in table 10. In all five comparative trials the differences

    between the two experimental years 2009 and 2010 were statistically assured.

    Table 10 Analysis of variance of the protein content for the self pollinated isonuclear inbred maize

    lines that were tested (ARDS Turda, 2009-2010) Isonuclear line

    TC209 Isonuclear line

    TC243

    Isonuclear line

    TC221 Isonuclear line

    TB367 Isonuclear line

    D105

    Cause of variability DF

    SP s2 SP s2

    DF

    SP s2 SP s2 SP s2

    Experimental years (Y) 1 68.15 68.15** 21.07 21.07** 1 0.09 0.09* 8.49 8.49* 104.60 104.60** Genotype 27 39.69 1.47** 55.48 2.05** 20 31.65 1.58** 17.91 0.90** 42.65 2.13**

    Cytoplasm (C) (6) 8.66 1.44** 10.92 1.82** (6) 4.76 0.79** 11.96 1.99** 9.12 1.52** Tester (T) (3) 13.83 4.61** 25.87 8.62** (2) 14.78 7.39** 2.56 1.28** 26.68 13.34**

    (C×T) interaction (18) 17.21 0.96** 18.69 1.04** (12) 12.11 1.01** 3.38 0.28** 6.84 0.57** (Y×T) interaction 3 7.86 2.62** 26.32 8.77** 2 3.05 1.52** 8.90 4.45** 12.37 6.19** (Y×C) interaction 6 6.59 1.10** 2.64 0.44** 6 26.79 4.47** 7.08 1.18** 7.11 1.18**

    (Y×T×C) interaction 18 11.65 0.65** 6.79 0.38** 12 15.18 1.27** 4.81 0.40** 6.45 0.54** Repetition ( R ) 2 0.06 0.03 0.16 0.08 2 0.18 0.09 0.19 0.10 0.02 0.01

    Error Y 2 0.03 0.01 0.16 0.08 2 0.01 0.00 0.49 0.25 0.08 0.04 Error T 12 0.70 0.06 1.42 0.12 8 1.49 0.19 0.35 0.04 0.28 0.04 Error C 96 4.65 0.05 5.50 0.06 72 4.89 0.07 7.80 0.11 4.86 0.07

    In all five test groups there were differences between genotypes and the differences

    were distinctly significant statistically. Cytoplasms have provided statistically significant

    differences in all five test groups, with an evident role of the cytoplasm in the differentiation

    of the genotypes. The highest values were recorded for testers variance; lower values, but

    distinctly significant statistically were shown by the „nucleus-cytoplasm” interactions.

    In all five experimental situations interaction with experimental years was statistically

    significant. Share of the factors involved in the variance of protein content is shown in figure

    10. Influence of cytoplasm on the variance of protein content was between 15% and 22%.

    As expected, the share was higher for the testers, between 14% for TB367 and 63% for

    D105, quite high values were also recorded in most situations for cytoplasm × nucleus interactions, with values between 16% for D105 and 43% for TC209 (COSTE et al., 2011).

  • 30

    1- the share of cytoplasm effect variance;

    2 - the share tester effect variance; 3 - the share „cytoplasm × tester” interaction effect variance Fig. 10. Share of each factor involved in the genetic variance of protein contet for the

    five groups of self pollinated isonuclear inbred lines that were tested 5.2.2. Study on protein content inheritance

    General combining ability effects for the cytoplasm and testers and the specific

    combining capacity due to „cytoplasm x testers” interaction for the group of lines TC243 is

    shown in table 11.

    Average protein content in the tested isonuclear inbred lines generated by TC243

    inbred line was 11.6%. With statistically significantly higher average values of content, thus

    with higher values of transmission at cytoplasm level stood the isonuclear lines: TC243

    (cit.TC221) - ĝcit = 0.29% and TC243-ĝcit =0.25%; in both cases the difference from ĝcit

    registered for control is statistically significant. With negative values for the transmission of

    protein content were noted TC243 (cit.A665)-ĝcit =- 0.40% and TC243 (cit.TC208) - ĝcit =

    -0.34%.

    Among the inbred tester lines, highest combining capacity at an additive level was

    registered for the tester line from indurata convariety Lo3Rf with an overall combining

    TC209

    43%22%

    35%

    1 2 3

    TC243

    34%20%

    47%

    1 2 3

    TC221

    38%

    15%

    47%

    1 2 3

    TB367

    19%

    14%67%

    1 2 3

    D105

    16% 21%

    63%

    1 2 3

  • 31

    capacity of 0.55% and the lowest value was registered for the tester inbred line TC344 -

    0.56%

    For the hybrid combinations, the values of specific combining ability ranged from -

    0.71% for the hybrid combination TC243 (cit.A665) × TC344 to 0.83% for the hybrid

    combination TC243 × TC344. The results of this comparative trial showed that the share of

    cytoplasm effects, additive effects of the testers and interactions of „cytoplasm × tester”

    would be relatively close, but that the importance of cytoplasm’s and testers would be

    decisive in determinism of the protein content of hybrids:

    - TC243(cit.K1080)×Lo3Rf= 12.6% = μ(+11.6%)+ ĝcit(+0.18%)+ ĝtest(+0.55%)+ŝcit x

    test(0.26%)

    - TC243(cit.TC221)×Lo3Rf=12.5%=μ(+11.6%)+ĝcit(+0.29%)+ĝtest(+0.55%)+ŝcit × test (0.10%)

    Table 11

    General and specific combining ability involved in the inheritance of protein content for the self pollinated isonuclear inbred maize lines that were tested

    TC243 (ARDS Turda, 2009-2010) TC344 Lo3Rf TB329 TD233

    cytoplasm/tester % ŝ cit ×test % ŝ cit ×test % ŝ cit ×test % ŝ cit ×test

    x ĝcit

    TC243 11.9 0.83 12.2 0.02 11.1 -0.51 11.3 -0.34 11.7 0.06 TC243(cit.A665) 9.9 -0.71 12.0 0.26 11.6 0.40 11.3 0.04 11.2 -0.40 TC243(cit.T248) 11.4 0.43 11.8 -0.33 11.3 -0.30 11.8 0.20 11.6 -0.03

    TC243(cit.TC208) 10.6 -0.13 11.8 -0.01 11.3 0.09 11.3 0.06 11.2 -0.34 TC243(cit.TC221) 11.0 -0.36 12.5 0.10 12.0 0.13 12.0 0.13 11.9 0.29 TC243(cit.K1080) 11.1 -0.14 12.6 0.26 12.1 0.34 11.3 -0.47 11.8 0.18 TC243(cit.K2051) 11.4 0.08 12.1 -0.31 11.7 -0.15 12.2 0.38 11.8 0.25

    Mean for tester 11.0 12.1 11.6 11.6 11.6 0.00 ĝtest -0.56 0.55 -0.01 0.02 11.6 0.00

    LDS 5% comparison ĝcytoplasm 0.14 LDS 5% comparison ĝtester 0.16 LDS 5% comparison for interaction c × t 0.27

  • 32

    5.3.3. Variance of oil content

    Oil content in maize is important; but when the kernels are used in the industry to

    manufacture alcohol, bioethanol and fodder, corn oil and soluble fiber are a byproduct of

    major importance that must be exploited.

    Analysis of variance in oil content of the five groups of self pollinated isonuclear

    lines is presented in table 12. From this table one can conclude that the experimental years

    didn’t provide statistically significant values except for the TC221 isonuclear group, the

    other studied test groups showed no influence of the experimental years on the oil content.

    Table 12 Analysis of variance of the oil content for the self pollinated isonuclear inbred maize lines

    that were tested (ARDS Turda, 2009-2010) Isonuclear line TC209 Isonuclear line TC243 Isonuclear line TC221 Isonuclear line TB367 Isonuclear line D105 Cause of variability DF

    SP s2 SP s2

    DF

    SP s2 SP s2 SP s2

    Experimental years (Y) 1 0.05 0.05 0.00 0.00 1 9.45 9.45** 0.52 0.52 0.46 0.46

    Genotype 27 27.75 1.03** 40.36 1.49** 20 6.16 0.31** 5.54 0.28 6.08 0.30**

    Cytoplasm (C) (6) 1.95 0.33** 0.27 0.04 (6) 1.88 0.31** 3.20 0.53** 0.81 0.14**

    Tester (T) (3) 24.39 8.13** 38.63 12.88** (2) 3.52 1.76** 0.88 0.44* 3.46 1.73**

    (C×T) interaction (18) 1.41 0.08* 1.47 0.08* (12) 0.75 0.06 1.46 0.12 1.81 0.15

    (Y×T) interaction 3 0.45 0.15 0.96 0.32** 2 0.76 0.38 0.55 0.28 2.44 1.22**

    (Y×C) interaction 6 1.75 0.29** 1.13 0.19** 6 4.23 0.70** 0.74 0.12 2.28 0.38**

    (Y×T×C) interaction 18 1.83 0.10** 3.34 0.19** 12 1.04 0.09 2.49 0.21* 1.73 0.14

    Repetition ( R ) 2 0.36 0.18 0.01 0.00 2 0.47 0.23 0.39 0.19 0.22 0.11

    Error Y 2 0.09 0.04 0.04 0.02 2 0.07 0.04 0.27 0.14 0.38 0.19

    Error T 12 1.27 0.11 0.38 0.03 8 1.15 0.14 1.00 0.13 0.25 0.03

    Error C 96 4.37 0.05 4.47 0.05 72 7.38 0.10 7.24 0.10 7.52 0.10

    Cytoplasms have provided statistically significant differences in four of the five test

    groups, with an important role in the differentiation of genotypes. The highest values of

    variance were recorded for testers being distinctly significant in all five groups of

    isonucleare lines. Statistically significant values were also recorded for the interactions

    between cytoplasm × experimental years, years × testers and interaction of the three factors

    (years × testers × cytoplasm).

  • 33

    The share of factors involved in the inheritance of oil content for the self pollinated

    ears is presented in figure 11 (model of LEIN quoted by CEAPOIU, 1969).

    Cytoplasm’s influence on the variance of oil content was between 1% and 58%. As

    expected the share for the testers was higher and ranged from 16% for the group of TB367

    isonuclear lines and 96% for the group of TC243 isonuclear lines. Relativly high values of

    cytoplasm × nucleus interaction was recorded for the group of TC243 isonuclear lines (4%)

    and 30% for the group of D105 isonuclear lines.

    1- the share of cytoplasm effect variance;

    2 - the share tester effect variance; 3 - the share "cytoplasm × tester" interaction effect variance Fig. 11. Share of each factor involved in the genetic variance of oil content for the

    five groups of self pollinated isonuclear inbred lines that were tested

    5.4.4. Study of oil content inheritance

    The effects of general and specific combining ability involved in the inheritance of oil

    content for the group of isonuclear lines generated by TB367 (self pollinated) are presented

    in table 13.

    TC209

    5% 7%

    88%

    1 2 3

    TC243

    4%1%

    96%

    1 2 3

    TC221

    12%31%

    57%

    1 2 3

    TB367

    26%

    16%58%

    1 2 3

    D105

    30%13%

    57%

    1 2 3

  • 34

    Average oil content of the experimental system was 5%. The effects of general

    combining ability at cytoplasm level ranged from -0.32% for TB367 (cit.TB329) and 0.22%

    for TB367 (cit.TC208).

    Among the inbred tester lines, the highest combining ability was provided by the

    TC209 inbred line (0.12%) and the lowest was recorded for T291 line (-0.07%).

    For the hybrid combinations, values of the specific combining ability ranged from -

    0.19% for the TB367 (cit.TC221) × TD233 hybrid combination to 0.23% for the TB367

    (cit.TC209) × TD233 hybrid combination.

    In the determination of oil content in hybrids with the highest values have contributed

    primarily the mean effects, but also equally important were the cytoplasm effects, nucleus

    and „nucleus-cytoplasm” interactions.

    - TB367(cit.TC208)×TC209=5.4%=μ(5%)+ĝcit(0.22%)+ĝtest(0.12%)+ŝcit×test (0.04%)

    - TB367(cit.TC221)×TC209=5.3%=μ(5%)+ĝcit(0.11%)+ĝtest(0.12%)+ŝcit×test (0.08%)

    Table 13 General and specific combining ability involved in the inheritance of oil content for the self

    pollinated isonuclear inbred maize lines that were tested TB367 (ARDS Turda, 2009-2010)

    T291 TC209 TD233 cytoplasm/tester

    % ŝ cit ×test % ŝ cit ×test % ŝ cit ×test x ĝcit

    TB367 4.8 -0.05 5.3 0.18 4.8 -0.13 5.0 -0.08 TB367(cit.T248) 4.9 0.02 5.1 -0.02 5.0 0.01 5.0 -0.04

    TB367(cit.TB329) 4.8 0.12 4.8 -0.07 4.6 -0.04 4.7 -0.32 TB367(cit.TC208) 5.1 -0.05 5.4 0.04 5.2 0.02 5.2 0.22 TB367(cit.TC221) 5.2 0.16 5.3 0.08 4.9 -0.19 5.1 0.11 TB367(cit.TC209) 5.0 -0.07 5.1 -0.16 5.3 0.23 5.1 0.06 TB367(cit.K2051) 4.9 -0.09 5.2 -0.04 5.2 0.12 5.1 0.06

    Media testeri Mean for tester 5.0 5.1 5.0 5.0 0.00

    ĝtest -0.07 0.12 -0.04 5.0 0.00 LDS 5% comparison ĝcytoplasm 0.21 LDS 5% comparison ĝtester 0.18 LDS 5% comparison for interaction c × t 0.36

  • 35

    CAPITOLUL VI STUDY OF PROTEIN AND OIL CONTENT INHERITANCE IN A DIALLEL

    SYSTEM TYPE P (P-1) Maize proteins are not of a very high quality due to a large content of zein, a protein

    fraction insoluble in water, soluble in alcohol. However the improvement of maize protein

    quality is of great interest for all breeding programs, latest research efforts aiming to

    improve the ratio of protein fractions, by other techniques than using opaque-2 and floury-2

    genes (SARCA, 2004).

    Increasing protein content was the subject of research works for nearly a century.

    ALEXANDER (1988) presents that after reviewing the Illinois program, initiated by

    Hopkins at the end of XIX century, the variability for this character is not exhausted, after

    76 generations of selection, the frequency of favorable alleles increased by 37%. Negative

    correlations were found between production capacity and protein content, but CĂBULEA et

    al. (1984) argues that the two traits can be improved simultaneously.

    The literature shows that in the genetic determinism of oil content variance of the

    general combining ability (GCA) was higher than specific combining ability (SCA),

    indicating a preponderance of additive genetic variance. Therefore to improve the oil content

    different methods of selection are used, most frequently, the recurrent selection (MISEVIC

    and ALEXANDER, 1989; MISOVIC et al. 1990, HAŞ et al., 2004).

    Oil content was analyzed both from self pollinated ear samples and from open

    pollinated ear samples. Differences between the two origins of the analyzed kernels should

    not be so great, because after ALEXANDER (1988) about 83% of the oil content of the

    maize kernel comes from the embryo.

  • 36

    6.1. PROTEIN CONTENT IN SELF POLLINATED KERNELS

    Gene effects involved in the protein content determinism for kernels from self

    pollinated hybrids in a diallel system, values are presented in tables 14-16.

    The average protein content for the two experimental years was 11.89%, with values

    between 11.11% for TC209 × TC344 hybrid and 13% for hybrid T291 × K1080. Statistically

    significant values that exceeded the average of the experimental system were reached by:

    T248 x T291 (0.50%), T248 × TC209 (0.38%), T291 × TC344 (0.34%) hybrids.

    Between the mean of the two experimental years there were statistically significant

    differences, 12.71% in 2009 and 11.07 in 2010. Maximum protein content of 13.40% was

    recorded fore T248xT291 hybrid in 2009 and the minimum value of 9.99% for the

    TC209xTC344 hybrid in 2010.

    Between direct and reciprocal hybrids there were statistically significant differences,

    the highest values were recorded in the following hybrids:

    - T248×TC209, lower protein content of 0.87% for the direct hybrid

    compared to the reciprocal hybrid;

    - TC209×TC344, lower protein content of 0.70% for the direct hybrid

    compared to the reciprocal hybrid;

    - TC209×K1080, lower protein content of 0.76% for the direct hybrid

    compared to the reciprocal hybrid;

    - TC208×T209, higher protein content of 0.75% compared to the reciprocal

    hybrid;

    - T291×TC344, higher protein content of 0.47% compared to the reciprocal

    hybrid.

    Differences between direct and reciprocal hybrids could result from the reciprocal

    effects of the „nucleus-cytoplasm” interaction (values between -0.57 and +0.43) and to a

    lesser extent, maternal effects, which for some parental forms have values that must be taken

    into account (K1080-m = 0.08; T291-m = 0.05; TC344-m =- 0.07; TC209-m =- 0.05).

  • 37

    The highest general combining ability for transmission of high protein content has

    been registered for the T291 inbred line 12, 21% (ĝi = +0.32).

    Low values for the transmission of protein content (additive gene effects with minus

    sign) occurred in TC208 inbred lines 11. 62% (ĝi =- 0.28) and TC209 11. 66% (ĝi =- 0, 24).

    Unadditive effects for some hybrid combinations had high absolute values,

    highlighting the importance of specific combining capacity in the determinism (high or low)

    of protein content

    - T248xTC209-ŝij=+0.52;

    - T291xK1080- ŝij=+0.49;

    - TC208xK1080- ŝij=+0.33;

    - TC209xTC344- ŝij=-0.35;

    - T291xTC209- ŝij=-0.35;

    - T248xK1080- ŝij=-0.27;

    We can conclude that in the protein content determinism of the self pollinated maize

    ears additive gene effects, unadditivee gene effects and the reciprocal effects of the

    „nucleus-cytoplasm” interactions are of equal importance, the maternal gene effects being

    less important.

    Concerning the protein level in the determination of the optimal hybrid combination

    formula it is necessary to test both direct hybrid and the reciprocal one.

  • 38

    Table 14 Protein content of the direct and reciprocal hybrids from a diallel system p (p-1) and the

    genetic effect rij of the specific interactions between the maternal cytoplasm and the nuclear genes (ARDS Turda, 2009-2010, self pollinated)

    % Protein content

    (%)

    crt.nr. Single cross

    hybrid A × B B × A Difference rij 2009 2010 Mean

    content

    % compared

    to the system mean medie mean

    1 T248 × T291 12.62 12.17 0.45 0.31 13.40 11.38 12.39 104.2 2 T248 × T208 11.62 11.42 0.20 -0.08 12.29 10.75 11.52 96.9 3 T248 × TC209 11.83 12.70 -0.87 -0.57 12.72 11.82 12.27 103.2 4 T248 × TC344 11.88 11.52 0.36 0.07 12.82 10.59 11.70 98.4 5 T248 × K1080 11.97 12.05 -0.08 0.02 13.22 10.80 12.01 101.0 6 T291 × TC208 11.87 11.72 0.15 -0.24 12.49 11.10 11.79 99.2 7 T291 × TC209 11.73 11.52 0.21 -0.17 12.15 11.10 11.63 97.8 8 T291 × TC344 12.47 12.00 0.47 -0.01 12.67 11.80 12.23 102.9 9 T291 × K1080 13.05 12.95 0.10 -0.02 13.25 12.75 13.00 109.3 10 TC208 × TC209 11.80 11.05 0.75 0.43 12.30 10.55 11.43 96.1 11 TC208× TC344 10.98 11.68 -0.70 -0.27 12.34 10.34 11.34 95.3 12 TC208 × K1080 12.08 11.93 0.15 0.33 12.89 11.14 12.01 101.0 13 TC209 × TC344 11.27 10.95 0.32 0.24 12.23 9.99 11.11 93.4 14 TC209 × K1080 11.47 12.23 -0.76 -0.13 12.73 10.97 11.85 99.6 15 TC344 × K1080 11.98 12.22 -0.24 0.12 13.15 11.05 12.10 101.8 Mean 11.91 11.87 0.03 12.71 11.07 11.89 100.0 LDS 5% comp. years 0.06 LDS 5% comp. hybrids 0.28 LDS comp. int years × hybrids 0.39

    Comparison of rij to rji - 0.0492

  • 39

    Table 15 Additive genetic effects (ĝi) and the maternal effects involved in the inheritance of protein content from a diallel crossing system p (p-1) (ARDS Turda, 2009-2010, self pollinated)

    The constant inbred line ♀ % ĝi (m)

    ♂ % ĝj(t)

    CCG % ĝ Maternal effects

    T248 11.98 0.09 11.97 0.08 11.98 0.09 0.01 T291 12.26 0.37 12.16 0.27 12.21 0.32 0.05

    TC208 11.60 -0.29 11.63 -0.26 11.62 -0.28 -0.01 TC209 11.60 -0.29 11.71 -0.18 11.66 -0.24 -0.05 TC344 11.63 -0.26 11.76 -0.13 11.70 -0.20 -0.07 K1080 12.28 0.39 12.11 0.22 12.19 0.30 0.08

    System mean 11.89 11.89 11.89 Comparison of ĝi to ĝj - 0.01467 Comparison of mi to mj - 0.00984

    Table 16 Mean protein content and the unadditive gene effects in a diallel system p (p-1)

    (ARDS Turda, 2009-2010, self pollinated)

    T 248 T 291 TC 208 TC 209 TC 344 K 1080 T 248 12.62 11.62 11.83 11.88 11.97

    ŝij 0.10 -0.18 0.52 -0.08 -0.27 r 0.31 -0.08 -0.57 0.07 0.02

    T 291 12.17 11.87 11.73 12.47 13.05 ŝij -0.14 -0.35 0.22 0.49 r -0.24 -0.17 -0.01 -0.02

    TC 208 11.42 11.72 11.8 10.98 12.08 ŝij 0.05 -0.09 0.09 r 0.43 -0.27 0.33

    TC 209 12.70 11.52 11.05 11.27 11.47 ŝij -0.35 -0.11 r 0.24 -0.13

    TC 344 11.52 12.00 11.68 10.95 11.98 ŝij 0.10 r 0.12

    K 1080 12.05 12.95 11.93 12.23 12.22 ŝij r

    Comparison of ŝij to ŝik - 0.04428 Comparison of ŝij to ŝkl - 0.02952

  • 40

    6.2. OIL CONTENT IN SELF POLLINATED KERNELS

    Oil content and gene effects involved in the determinism of this character for the self

    pollinated kernels are presented in tables 17-19.

    Average content for the hybrids obtained in the diallel system was 4.65%, with no

    differences between the two experimental years. The hybrid with the highest oil content was

    T248xTC344 (5.01%), followed by TC208xTC344 (4.99%) the lowest content was recorded

    in the hybrid combination T291xK1080 (4.09%). Between direct and reciprocal hybrids has

    been an average difference of 0.09%; but the difference between direct and reciprocal

    individual hybrids presented higher amplitudes:

    - T291xTC208 difference between direct and reciprocal hybrid was -0,58%;

    - TC208xTC209 difference between direct and reciprocal hybrid was -0,33%;

    - T248xTC209 difference between direct and reciprocal hybrid was -0,30%;

    Differences between direct and reciprocal hybrids are mostly determined by „nucleus-

    cytoplasm” effects with values between -0.25 for the T248xTC209 hybrid combination and

    +0.23 for the T291xTC344 hybrid combination. The comparisons between unadditive gene

    effects and reciprocal effects of the interaction of nuclear genes and cytoplasm are presented

    in table 19, it can be seen that in many cases, reciprocal effects were higher than the

    unadditive gene effects.

    In the determinism of phenotypic differences for the amount of oil between reciprocal

    and direct hybrids maternal gene effects are also involved, but with lower value then the

    reciprocal effects.

    General combining ability effects are presented in table 18. Highest oil content is

    transmitted by the TC344 inbred line (x = 4.92%, ĝi = 0.27). The lowest oil content is

    transmitted by the T291 inbred lines (x = 4.50%, ĝi =- 0.15) and K1080 (x = 4.69%, ĝi =-

    0.14).

  • 41

    From the presented data we conclude that in heredity of oil content (in kernels from

    the self pollinated ears) additive gene effects, reciprocal effects of „nucleus-cytoplasm”

    interactions and unaditive gene effects are involved.

    Table 17 Oil content of the direct and reciprocal hybrids from a diallel system p (p-1) and the genetic efect rij of the specific interactions between the maternal cytoplasm and the nuclear genes

    (ARDS Turda, 2009-2010, self pollinated)

    % Oli content

    (%)

    crt.nr. Single cross

    hybrid A × B B × A Difference rij 2009 2010 Mean

    content

    % compared

    to the system mean medie mean

    1 T248 × T291 4.60 4.83 -0.23 -0.22 4.82 4.62 4.72 101.5 2 T248 × T208 4.72 4.78 -0.06 -0.09 4.80 4.70 4.75 102.2 3 T248 × TC209 4.52 4.82 -0.30 -0.25 4.87 4.47 4.67 100.4 4 T248 × TC344 5.10 4.92 0.18 0.19 5.07 4.95 5.01 107.8 5 T248 × K1080 4.67 4.63 0.04 -0.08 4.75 4.55 4.65 100.1 6 T291 × TC208 4.25 4.83 -0.58 -0.22 4.58 4.50 4.54 97.7 7 T291 × TC209 4.33 4.35 -0.02 0.01 4.22 4.47 4.34 93.4 8 T291 × TC344 4.82 4.80 0.02 0.23 4.88 4.74 4.81 103.4 9 T291× K1080 4.15 4.03 0.12 0.08 4.04 4.15 4.09 88.1 10 TC208 × TC209 4.35 4.68 -0.33 -0.23 4.45 4.58 4.52 97.1 11 TC208 × TC344 4.90 5.08 -0.18 0.04 5.00 4.99 4.99 107.4 12 TC208 × K1080 4.40 4.32 0.08 -0.03 4.24 4.49 4.36 93.8 13 TC209 × TC344 4.83 4.85 -0.02 0.14 4.73 4.95 4.84 104.1 14 TC209 × K1080 4.40 4.57 -0.17 -0.13 4.32 4.65 4.48 96.4 15 TC344 × K1080 4.98 4.92 0.06 -0.17 4.85 5.05 4.95 106.5 Mean 4.60 4.69 -0.09 4.64 4.66 4.65 100.0 LDS 5% comp. years 0.19 LDS 5% comp. hybrids 0.24 LDS comp. int years × hybrids 0.33

    Comparison of rij to rji - 0.038208

  • 42

    Table 18 Additive genetic effects (ĝi) and the maternal effects involved in the inheritance of oil

    content from a diallel crossing system p (p-1) (ARDS Turda, 2009-2010, self pollinated)

    The constant inbred line ♀ % ĝi (m)

    ♂ % ĝj(t)

    CCG % ĝ Maternal effects

    T248 4.72 0.07 4.80 0.15 4.76 0.11 -0.04 T291 4.48 -0.17 4.52 -0.13 4.50 -0.15 -0.02

    TC208 4.65 0.00 4.61 -0.04 4.63 -0.02 0.02 TC209 4.62 -0.03 4.52 -0.12 4.57 -0.08 0.05 TC344 4.93 0.28 4.91 0.27 4.92 0.27 0.01 K1080 4.49 -0.15 4.88 -0.13 4.69 -0.14 -0.01

    System mean 4.65 4.71 4.68 Comparison of ĝi to ĝj - 0.011463 Comparison of mi to mj - 0.007642

    Table 19 Mean oil content and the unadditive gene effects in a diallel system p (p-1)

    (ARDS Turda, 2009-2010, self pollinated)

    T 248 T 291 TC 208 TC 209 TC 344 K 1080 T 248 4.6 4.72 4.52 5.1 4.67

    ŝij 0.10 0.01 -0.01 -0.02 0.03 r -0.22 -0.09 -0.25 0.19 -0.08

    T 291 4.83 4.25 4.33 4.82 4.15 ŝij 0.06 -0.08 0.04 -0.27 r -0.22 0.01 0.23 0.08

    TC 208 4.78 4.83 4.35 4.9 4.4 ŝij -0.04 0.09 -0.13 r -0.23 0.04 -0.03

    TC 209 4.82 4.35 4.68 4.83 4.4 ŝij 0.00 0.06 r 0.14 -0.13

    TC 344 4.92 4.8 5.08 4.85 4.98 ŝij 0.17 r -0.17

    K 1080 4.63 4.03 4.32 4.57 4.92 ŝij r

    Comparison of ŝij to ŝik - 0.034388 Comparison of ŝij to ŝkl - 0.022925

    Given the high level of reciprocal effects of „nucleus-cytoplasm” interaction it is

    necessary to test direct and reciprocal combinations in order to establish the best formulas

    for obtaining high-oil hybrids

  • 43

    CHAPTER VI

    CONCLUSIONS

    1. Analysis of maize germoplasm consisting of local populations, synthetic

    populations and inbred lines of maize from ARDS Turda regarding protein and oil content

    showed the existence of significant genetic variability that can be used to obtain corn

    hybrids with high protein and oil content.

    2. The variance of protein content in local populations of maize ranged between

    11.20% and 15.60%, with an average of 13.69%, while oil content ranged between 3.80%

    and 7.30%, with an average of 5.38%.

    3. The variance of protein content in inbred maize lines ranged between 10.80% and

    17.70%, with an average of 13.43%, as oil content ranged between 2.40% and 7.60%, with

    an average of 4.16%.

    4. Potential use in the increase of protein and oil content in maize were shown by the

    following populations and inbred lines:

    - local population Satu Lung/01(15.6% protein and 6.7% oil) and

    Salva/01(15.5% protein and 7.1% oil)

    - inbred lines :

    - TC106(16.4% protein and 7,5% oil) and T442(15.6% protein and 7.2% oil)

    inbred lines with flint kernels

    - TC334(15.1% protein and 7.5% oil), T167(14.8% protein and 5.8% oil) and

    T166(15.1% protein and 5.5% oil) inbred lines with flint × dent

    - TC344A(15.2% protein and 7.6% oil), TB370(16% protein and 6.1% oil) şi

    TC337(protein 15.5% and 5.9% oil) inbred lines with dent × flint kernels

    - TC375(14.7% protein and 7.1% oil), TC353(15.1% protein and 5.6% oil) and

    TD290(15.3% protein and 5.3% oil) inbred lines with dent kernels

    5. In a balanced genetic system, with five inbred lines whose nucleus was transferred

    by backcrossing (9-10) on four types of cytoplasms, in the heredity of protein and oil

  • 44

    content genetic factors located in the nucleus, the cytoplasm and interaction between

    factors located in cytoplasm and nucleus are involved.

    6. In this balanced system, in the heredity of protein content, cytoplasm factors are

    involved in a share of 7% and „nucleus-cytoplasm” interactions in a share of 57%. In

    heredity of oil content cytoplasm factors have a minor contribution (1%), cytoplasm and

    nucleus interactions having a contribution of 10%

    7. In the balanced genetic system cytoplasm derived from the T248 line has led to an

    increase of protein content in the isonuclear lines by 0.27%, in turn, cytoplasm derived

    from TC221 inbred line reduced protein content by 0.29%. In both cases differences are

    distinctly significant statistically.

    8. Although the contribution of cytoplasm in heredity of oil content is reduced, the

    cytoplasm of the TC177 inbred line has a significantly distinct positive contribution

    (+0.31%) in improving oil content in the newly created isonuclear lines.

    9. The nucleus transfer form the TB367 inbred line on the cytoplasm of the TC177 and

    TB329 lines increased the oil content with 1.23% and 0.50%.

    10. Study of protein and oil content of five sets of isonulcear inbred lines (each line

    transferred on to six types of cytoplasm), under self pollinated or open pollinated

    conditions revealed specific interactions between the type of cytoplasm and the transferred

    nucleus to increase / decrease protein and oil content.

    11. The results obtained for the protein content from open-pollinated kernels do not

    always confirm the results obtained from self pollinated kernels. For this reason we believe

    that self pollinated kernels give more accurate results regarding protein and oil content

    when corn genotypes are cultivated on large surface areas, where opportunities for cross

    pollination are reduced.

    12. The oil content inheritance for the tested isonucleare inbred lines is influenced

    primarily by the overall transmission capacity of the testers, by the genes with localization

    in cytoplasm and „nucleus × cytoplasm” interaction. Share of variance for cataplasms

    ranged between 1 and 58% for self pollinated ears and between 4 and 41% for open

    pollinated ears.

  • 45

    13. Heredity study of the protein content using a diallel system p (p-1) revealed the

    importance of mean effects, general combining ability effect, specific combining ability

    effects and the equally important effects of reciprocal interactions of „cytoplasm x

    nucleus”. Maternal effects appear to be less important in the transmission of protein

    content.

    14. In the oil content heredity, studied in a diallel system on self pollinated and open

    pollinated kernels revealed that additive gene effects, unaditive gene effects and reciprocal

    interactions of „nucleus-cytoplasm” are important, maternal effects can be neglected.

    15. Given the high level of reciprocal effects of „nucleus-cytoplasm” interaction it is

    necessary to test direct and reciprocal combinations to determine the best hybrid

    combinations to establish formulas for simple hybrids with high oil content.

  • 46

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