3b seed development

SEED DEVELOPMENT SEED DEVELOPMENT (MATURATION)(MATURATION)

JULIO MARCOSJULIO MARCOS--FILHOFILHODEPT. OF CROP SCIENCEDEPT. OF CROP SCIENCE

USP/ESALQUSP/ESALQ

INTRODUCTIONINTRODUCTION

Start Start flower induction and differentiationflower induction and differentiation

22

Seed development : a sequence of events Seed development : a sequence of events controlled by the genotypecontrolled by the genotype

Flowering and pollination are not uniform in Flowering and pollination are not uniform in the same plant or within a populationthe same plant or within a population

Maturation: set of successive stages in Maturation: set of successive stages in preparation for successful seed germinationpreparation for successful seed germination

INTRODUCTIONINTRODUCTION

33

Initial studies: aimed at determining Initial studies: aimed at determining phenologicalphenologicaldifferences among species and the optimum harvest differences among species and the optimum harvest timetime

First proposed criteria to identify seed maturity:First proposed criteria to identify seed maturity:

-- Time from planting or seedling emergence to Time from planting or seedling emergence to harvestingharvesting

-- Seed moisture content and morphological Seed moisture content and morphological characteristics to identify seed maturitycharacteristics to identify seed maturity

Delouche (1971) :Delouche (1971) :

Seed maturationSeed maturation is a process that comprises a is a process that comprises a set of morphological, physical, physiological set of morphological, physical, physiological and biochemical events that occur from ovule and biochemical events that occur from ovule fertilization to the moment in which seeds fertilization to the moment in which seeds become physiologically independent of the become physiologically independent of the parent plantparent plant

SEED DEVELOPMENTSEED DEVELOPMENT

44

Dure III (1975)Dure III (1975)

Days after flowering

Embr

yo d

ry w

eigh

t

CELL DIVISION AND ELONGATION

(PHASES I and II)

RESERVE DEPOSITION(PHASE III)

DESICCATION(PHASE IV)

HISTODIFFERENTIATIONHISTODIFFERENTIATION

55

GENERAL PARAMETERS TO CHARACTERIZE SEED GENERAL PARAMETERS TO CHARACTERIZE SEED MATURATIONMATURATION

1960s and 1970s: individual seeds x plant 1960s and 1970s: individual seeds x plant populationpopulation

66

Seed sampling at preSeed sampling at pre--defined intervals and defined intervals and identification of parameters associated identification of parameters associated with maturation progresswith maturation progress

Definition of seed changes in seed technology Definition of seed changes in seed technology researchresearch

SEED MOISTURE CONTENTSEED MOISTURE CONTENT

Dry fruits x Fleshy fruitsDry fruits x Fleshy fruitsFinal dehydration

GENERAL PARAMETERS TO IDENTIFY SEED GENERAL PARAMETERS TO IDENTIFY SEED MATURATIONMATURATION

Ovule fertilization and evolution during Ovule fertilization and evolution during maturationmaturation

77

TIMETIME

Fresh weightFresh weight

Dry weightDry weight

Moisture Moisture contentcontent

Variations in moisture content, fresh weight and dry Variations in moisture content, fresh weight and dry weight during maturation of seed produced in dry (weight during maturation of seed produced in dry (-- -- --) ) or fleshy fruits ( ).or fleshy fruits ( ).((CarvalhoCarvalho and Nakagawa, 2000)and Nakagawa, 2000) 88

R6R6R5R5

SEED SIZESEED SIZE

Soybean pod and seed development (Ritchie et al., 1994)Soybean pod and seed development (Ritchie et al., 1994)


99

R6 R7 R8 1010

SEED SIZESEED SIZE


Species Period (days) Reference

Cotton 21-28 Carvalho (1972)

Soybean 64 Jacinto and Carvalho (1974)

Sorghum 15-20 Nagai (1973)

Wheat 40 Carvalho and Yanai (1976)

Days after flowering necessary for seeds of different species toDays after flowering necessary for seeds of different species to attain attain maximum size during maturation (maximum size during maturation (CarvalhoCarvalho and Nakagawa, 2000)and Nakagawa, 2000)

1111

2 5 8 11

2

4

6

Num

ber o

f ce

lls/s

eed

x 10

-6

number of cells

dry weight

10

40

30

20

(Dry

wei

ght (

mg/

seed

)

EgliEgli FrutFrut development period (Phase I)development period (Phase I) 1212

DRY WEIGHTDRY WEIGHT

SEED MOISTURE CONTENT + DRY WEIGHTSEED MOISTURE CONTENT + DRY WEIGHTMoisture contentMoisture content


1313EgliEgli


Species Moisture content (%) Reference

Cotton 50-60 Carvalho (1972)Peanut 47-50 Carvalho et al. (1976)Oat 45 Frey et al. (1958)Field bean 38-44 Neubern and Carvalho (1976)Maize 25-30 Hunter et al. (1991)Soybean 50 Andrews (1966)Sorghum 23-30 Kersting et al. (1961)Wheat 40 Carvalho and Yanai, 1976

Seed moisture content of different species at the time they reacSeed moisture content of different species at the time they reach h maximum dry weight during developmentmaximum dry weight during development

1414

Primary root protrusion x Normal seedlingsPrimary root protrusion x Normal seedlings

Germination x Dormancy during maturationGermination x Dormancy during maturation

1515

GENERAL PARAMETERS TO IDENTIFY SEED MATURATIONGENERAL PARAMETERS TO IDENTIFY SEED MATURATION

GERMINATIONGERMINATION

VIGORVIGOR

Initial germination (days) after ovule fertilization in some culInitial germination (days) after ovule fertilization in some cultivated tivated species (species (DeloucheDelouche, 1971), 1971)

SpeciesGermination

(days after anthesis) Rye 05Wheat 05Sorghum 06 to 10Clover 10Cotton 22Soybean 38

1616

Days after sowing

Moisture content

(%)

Seed dry weight

(mg/seed)

Germination(%)

Vigor(mg dry weight /

seedling)78 55.3 20.40 05 5.084 50.6 25.34 28 4.0790 48.1 28.80 77 7.4796 39.8 34.10 37 7.69102 27.2 36.44 11 4.86108 14.1 34.10 09 4.88111 11.0 37.24 06 5.53117 8.8 37.54 81 9.57123 9.9 37.90 83 10.72126 10.7 37.84 65 9.34

Variation of seed moisture content, dry weight, germination and Variation of seed moisture content, dry weight, germination and vigor vigor during wheat maturation, cv. IAS during wheat maturation, cv. IAS --54. (Carvalho and Yanai, 1976)54. (Carvalho and Yanai, 1976) 1717

DETERMINATION OF PHYSIOLOGICAL MATURITYDETERMINATION OF PHYSIOLOGICAL MATURITY

a) Seed maturity is identified by the maximum a) Seed maturity is identified by the maximum dry matter accumulation dry matter accumulation

b) Seed physiological maturity is reached b) Seed physiological maturity is reached when there are no significant increases in when there are no significant increases in seed dry weightseed dry weight

1818

c) Seed physiological maturity occurs when c) Seed physiological maturity occurs when seeds reach maximum dry weight, seeds reach maximum dry weight, germination, and vigorgermination, and vigor

CONCEPTSCONCEPTS

1919


Seed physiological maturity = maximum dry weightSeed physiological maturity = maximum dry weightPREVAILING IDEAPREVAILING IDEA

Relative MaturityRelative Maturity, , Morphological MaturityMorphological Maturity, , Mass Mass MaturityMaturity, , Harvest MaturityHarvest Maturity, , Agronomic Agronomic MaturityMaturity, , Time of HarvestTime of Harvest

Determination of physiological maturity in individuals Determination of physiological maturity in individuals or in plant communitiesor in plant communities

MOISTURE CONTENT SIZE

VIGOR

GERMINATION

DRY WEIGHT

2020

Days after sowingDays after sowing Moisture Moisture content (%)content (%)Seed dry weight Seed dry weight

(mg/seed)(mg/seed)6464 72.972.9 61.461.47070 60.560.5 158.4158.47676 56.856.8 171.0171.07979(()) 43.943.9 202.8202.88282 38.238.2 203.8203.88888 21.821.8 194.8194.89494 41.041.0 208.6208.6100100 30.030.0 206.4206.4106106 18.118.1 194.8194.8

Mean values of moisture content and dry weight during maturationMean values of moisture content and dry weight during maturation of of bean seeds, cv Carioca (Neubern and Carvalho, 1976) bean seeds, cv Carioca (Neubern and Carvalho, 1976)

2121

2222


Difficult to identify the exact point of seed Difficult to identify the exact point of seed physiological maturity (maximum dry weight)physiological maturity (maximum dry weight)

NEED TO INCREASE PRECISION:NEED TO INCREASE PRECISION:

-- Number of statistical replicatesNumber of statistical replicates

-- Reduce harvesting intervalsReduce harvesting intervals- Additional care in weighing

Use of Use of 14 14 C to monitor reserve accumulationC to monitor reserve accumulation

2323


Visual indicators of seed physiological maturity Visual indicators of seed physiological maturity

MAIZE:MAIZE:Black LayerBlack LayerMilk LineMilk Line

Pod and Seed Color Pod and Seed Color SOYBEAN:SOYBEAN:

20

40

60

80

100

Perc

enta

ge

Days after R349 63 77 90

GreenYellowYellow, typical of cultivar

PM

2424

Marcos-Filho (1979)

Black Layer

(Mississippi State University extension service, http://msucares.com/crops/corn/corn2.html)

2525

Mature

Physiological potential

Overripe

ContrerasContreras

Maturation of Maturation of tomatotomato

2626

SpeciesSpecies Mean periodMean period

(days)(days)LettuceLettuce 00OnionOnion -- 44TobaccoTobacco 00MaizeMaize

InbredInbredSingle hybridSingle hybridDouble hybridDouble hybrid

00--55

--1010SoybeanSoybean -- 77TomatoTomato +10+10WheatWheat -- 66

Average and range in days before or after physiological maturitAverage and range in days before or after physiological maturity and seed vigor y and seed vigor of different cultivated species (TeKrony and Egli, 1997) of different cultivated species (TeKrony and Egli, 1997)

(() () (--): days before seed maximum dry weight): days before seed maximum dry weight(+): days after seed maximum dry weight(+): days after seed maximum dry weight

2727

Days after Days after floweringflowering

GerminationGermination(()) Soluble SugarsSoluble Sugars(()) ProteinsProteins(())

FDFD SDSD FDFD SDSD FDFD SDSD

2626 0000 6868 1.11.1 0.10.1 0.570.57 0.090.09

3232 0000 6868 1.51.5 0.20.2 0.510.51 0.180.18

4242 6565 ---- 2.22.2 0.20.2 0.620.62 0.250.25

4848 5454 9393 1.61.6 0.40.4 0.480.48 0.190.19

Percentage germination, leakage of sugar and protein from soybeaPercentage germination, leakage of sugar and protein from soybean seeds, cv n seeds, cv Chippewea, submitted to drying at different maturation stagesChippewea, submitted to drying at different maturation stages

(Adams and Rinne, 1983) (Adams and Rinne, 1983)

(() FD ) FD seed threshing and fast drying immediately after harvest;seed threshing and fast drying immediately after harvest;SL SL slow seed drying still attached to pods.slow seed drying still attached to pods.

(() Germination (%); Seed leachate (mg/seed) ) Germination (%); Seed leachate (mg/seed) 2828

Days after anthesis


ContrerasContrerasMaturation of tomato

Physiological PotentialPhysiological Potential

2929

SEED MATURITY X HARVEST TIMESEED MATURITY X HARVEST TIME

- Determination of harvest time

-- Delayed harvest: problemsDelayed harvest: problems

3030

Date(L1)

Yield(kg/ha)

Date(L2)

Yield (kg/ha)

09/03/81 5.255 11/03/81 5.104

19/03/81 4.493 01/04/81 4.797

08/04/81 4.398 22/04/81 4.695

05/05/81 3.904 12/05/81 4.440

18/05/81 3.888 05/06/81 4.236

Effect of harvest time on maize seed yield in two locations of Parana state, Brazil (Hadlich, 1983) 3131

RH

RH

RH

RH

RH3232

3333

FIELD WEATHERINGFIELD WEATHERING

YEARYEAR PMPM HTHT 14*14* 28*28*

19731973 9494 8888 5858 5555

19741974 8585 8383 8585 4141

19751975 8989 8585 6666 5757

19761976 8383 2828 1313 0707

19771977 7171 6262 4040 0505

Vigor (accelerated aging) of Kent soybean seeds as influenced by harvest time for five experimental years (TeKrony et al., 1980).

3434PM = physiological maturity; PM = physiological maturity; HT = adequate HT = adequate

harvest time;harvest time; 14 and 28 = days after HT14 and 28 = days after HT

3535


-- Harvesting at physiological maturity?Harvesting at physiological maturity?

-- Variations in seed moisture content and Variations in seed moisture content and in plant characteristicsin plant characteristics

-- Visual parameters: Visual parameters: black layer, milk line, black layer, milk line, seed and/or fruit color, glumes and pedicelseed and/or fruit color, glumes and pedicel


-- Uniformity of maturationUniformity of maturation

3636

SoybeanSoybean TomatoTomato

CottonCotton

3737

I

II

III

Carrot

Umbel Order

Umbel / Plant

Proportion (%)

Germination (%)

First Count (%)

1000 seeds (g)

Primary 1 11 75 54 2.28Secondary 11 58 65 43 2.15Tertiary 24 31 54 37 1.99

Number of umbels per plant, contribution to plant seed production (%), germination (%), vigor (germination first count - %) and weight of 1000 seeds associated with umbel order in carrot (Nascimento, 1991)

3838

RESERVE ACCUMULATION DURING SEED RESERVE ACCUMULATION DURING SEED DEVELOPMENTDEVELOPMENT

3939

-- Sequence of genetically programmed eventsSequence of genetically programmed events

-- Monocots Monocots endosperm;endosperm; Dicots Dicots cotyledonscotyledons

-- Final yield: Final yield: seed numberseed number + + seed growth rateseed growth rate + + duration duration of seed fillof seed fill

1. NUTRIENT TRANSLOCATION FROM THE PARENT PLANT1. NUTRIENT TRANSLOCATION FROM THE PARENT PLANT

Photoassimilates (sugars, amino acids and other solutes) are transported via phloem


4040

Plant reserve accumulation in endospermic seedsPlant reserve accumulation in endospermic seeds

Nutrient translocation to seedsNutrient translocation to seeds

Short distance transportShort distance transport

NUTRIENT TRANSLOCATION NUTRIENT TRANSLOCATION short distanceshort distance

starchy endosperm

transfer cells

chalazal region

embryo

pedicelphloem

basal endosperm

4141

1. NUTRIENT TRANSLOCATION FROM THE PARENT PLANT1. NUTRIENT TRANSLOCATION FROM THE PARENT PLANT


Plant reserve accumulation in nonPlant reserve accumulation in non--endospermic seedsendospermic seeds

4242

f f

ct

eeh

NUTRIENT TRANSLOCATION NUTRIENT TRANSLOCATION short distanceshort distance

4343

Mature seeds Mature seeds two or three main types of reservestwo or three main types of reservesSynthesis is parallel during seed developmentSynthesis is parallel during seed development

Synthesis occurs in different cellular compartments: starch, in amyloplastslipids, in spherosomesproteins, in cytosol and endoplasmic reticulum

2. NUTRIENT ASSIMILATION2. NUTRIENT ASSIMILATION


4444

Nucleic acidsNucleic acids


CarbohydratesCarbohydrates

4545

LipidsLipids

ProteinsProteins

15 4515 304530

10

100

20

30

200

300

mg

0,1

0,3

0,5

0,02

0,04

0,06Dry Weight

Proteins

DNA

RNA

Days after fertilization

mg

whole seed endosperm embryo

MAIZEMAIZE

4646

mg

mg


LEGUMESLEGUMES

4747

Accumulation of carbohydrates precedes those of Accumulation of carbohydrates precedes those of lipids and proteinslipids and proteins

10

50

40

20

30

30 7050

Days after flowering

Perc

enta

ge

Proteins

Carbohydrates

Lipids

Changes in carbohydrate, lipid and protein contents during Changes in carbohydrate, lipid and protein contents during soybean seed development (Adapted from Konno, 1979)soybean seed development (Adapted from Konno, 1979) 4848

20

140

100

60

DNA

RNAproteins

cell division cell elongation

10 14 18 22 26Days after flowering

200

1400

1000

600

prot

eins

(mg/

coty

ledo

n)

RN

A (

g/co

tyle

don)

1

7

5

3

DN

A (

g/co

tyle

don)

4949

Stage Dry weight(mg/seed)

M.C.(%)

Proteins(mg/seed)

Oil(mg/seed)

Sugars(mg/seed)

R 4 0.2 78.4 ---- ---- ----R 5 5.9 83.1 2.5 0.1 1.3R 6 123.6 62.4 42.0 26.7 19.3R 7 194.2 51.9 71.9 31.7 30.8R 8 188.3 9.7 73.4 36.2 32.4

Variation in soybean composition during maturation Variation in soybean composition during maturation (Dornbos and McDonald, 1986)(Dornbos and McDonald, 1986)

5050

HORMONESHORMONES

5151

Abscisic acidAbscisic acid

Cytokinins

Gibberellins

AuxinsAuxins

ENVIRONMENTAL FACTORS AFFECTING SEED ENVIRONMENTAL FACTORS AFFECTING SEED DEVELOPMENTDEVELOPMENT

-- Soil FertilitySoil FertilityAdequate supply Adequate supply seed size and weightseed size and weight

- WaterEffects of water deficitsWater excess Time of occurrenceAssociation with temperature stress

5252

Association of water deficit and thermal stress during soybean Association of water deficit and thermal stress during soybean seed filling (Franseed filling (Frana Neto and Krzyzanowski)a Neto and Krzyzanowski)

5353

APROSMAT, 2006

water deficitwater deficit

alternate dry and humid

periods

5454

-- Temperature Temperature

ENVIRONMENTAL FACTORS AFFECTING SEED ENVIRONMENTAL FACTORS AFFECTING SEED DEVELOPMENTDEVELOPMENT

5555

Critical value: 35Critical value: 35ooC during seed fillingC during seed filling

Forced maturationForced maturation and greenish seedsand greenish seeds

5656

ColorGermination (%) Tetrazolium 1-3 (%) Emergence (%)

Initial 3 months Initial3

monthsInitial 3 months

Yellow 88 87 75 73 87 88

Green 60 19 52 20 58 38

Soybean: presence of green seeds and effects on germination and vigor (Scheren and Tolentino Jr, 2005)

5757

ENVIRONMENTAL FACTORS AFFECTING SEED DEVELOPMENT

-- LightLightPhotosynthesis x plant and seed performancePhotosynthesis x plant and seed performanceRetention of flowers and fruitsRetention of flowers and fruits

-- Seed position on the plantSeed position on the plant

5858

Seed 4Seed 4--stage developmental pattern: cell division, stage developmental pattern: cell division, cell elongation, reserve accumulation, desiccationcell elongation, reserve accumulation, desiccation

Seeds do not germinate while attached to the parent plant

During most of seed development:Formation and activity of enzymes involved in

synthesis processes, managed by m-RNA5959

ENVIRONMENTAL FACTORS AFFECTING SEED DEVELOPMENT

METABOLISM REVERSION FROM DEVELOPMENT TO METABOLISM REVERSION FROM DEVELOPMENT TO GERMINATIONGERMINATION

6060

Metabolic reversion from synthesis to hydrolysisMetabolic reversion from synthesis to hydrolysis

Synthesis and activity of ABASynthesis and activity of ABAHigh concentration during embryogenesisHigh concentration during embryogenesis

Synthesis and activity of ABASynthesis and activity of ABADecrease during late maturation desiccation Decrease during late maturation desiccation

Management by mManagement by m--RNARNA

HORMONE INFLUENCE HORMONE INFLUENCE

cyt gib aux

ABA

Fertilization Maturity

Seed dry weight

6161

Does drying play a role in this switch?

synthesissynthesis mobilizationmobilization

Desiccation is the Desiccation is the triggertrigger to switch to metabolism to switch to metabolism reversionreversion

Henk Hilhorst 6262

DESICCATION TOLERANCE DURING SEED DESICCATION TOLERANCE DURING SEED MATURATIONMATURATION

Desiccation during seed maturation:developmental pattern, driving seed embryo to a

quiescent stage in preparation for germination

Desiccation Tolerance:Desiccation Tolerance:The ability to recover biological functions after The ability to recover biological functions after

drying to equilibrium with moderately dry air and drying to equilibrium with moderately dry air and then resume normal function when rehydratedthen resume normal function when rehydrated

6363

This ability depends on the ability to maintain membrane structure and prevent protein denaturation

DESICCATION TOLERANCE DURING SEED DESICCATION TOLERANCE DURING SEED MATURATIONMATURATION

Desiccation Tolerance:Desiccation Tolerance:Intolerant Phase:Intolerant Phase:Cell division and elongation + part of reserve Cell division and elongation + part of reserve

accumulation period accumulation period

Premature and rapid desiccation:Damage to enzyme and protein synthesisLoss of cell turgidity, damage to cell membranes,enzymes, proteins and nucleic acid structure

6464

Tolerant Phase:Final phase of reserve accumulation

DESICCATION TOLERANCE DURING SEED MATURATIONDESICCATION TOLERANCE DURING SEED MATURATIONPROTECTIVE SUBSTANCES OR MECHANISMS PROTECTIVE SUBSTANCES OR MECHANISMS

-- LEA (LEA (late embryogenesis abundantlate embryogenesis abundant) Proteins) Proteins

-- Antioxidant systemsAntioxidant systems

-- Soluble sugars: raffinose, stachyose, sucroseSoluble sugars: raffinose, stachyose, sucrose

-- Heat shockHeat shock proteinsproteins

-- Slow dryingSlow drying6565

3b seed development

Documents

maturation of seed

seed maturationmaturation1960s

seed maturitycharacteristics

seed maturitydelouche

seed general parameters

seed maturationseed

identification of parameters

dry variations