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5.1 SUMMARY

5.1.1 Preparation and development of the alternative

bags/containers

5.1.2 Results of experiments with selected alternatives

5.2 CONCLUSIONS

5.2 LIMITATIONS OF THE PRESENT STUDY

5.3 RECOMMENDATIONS

Chapter 5…................................................... Summary & Conclusion .........................................................121

5.1. SUMMARY

In forestry, horticulture, floriculture nurseries polybags and plastic containers/root-

trainers are used in preparing plant culture and to transfer them to the other places. The use of

these plastic objects seems quit feasible owing to their low cost, apparent simplicity and

convenience in handling but problem lies with their non-biodegradable nature that impose

considerable threat to the environment along with all other fields of plastic uses. The purpose

of this research was to develop appropriate ecofriendly substitutes that could minimize the use

of polythene bags and plastic root-trainers in the plantation nursery. The study was based in

the premise that natural raw materials are utilized in the development/fabrication of these

substitutes as far as possible while pursuing following objectives:

1- Development of alternative ecofriendly nursery bags/containers

2- Testing of developed articles for porosity, soil weight carrying capacity and

strength

3- Estimation of effects of developed materials on seedling growth and plant

performance and comparison with conventional materials

4- Economic viability of developed products

This research started with the trial experiments to fulfill the first objective

(development of alternative ecofriendly nursery bags /containers). The first step of these trials

experiment was the selection of suitable raw materials that can be use to build these

alternatives. In trial experiments it was found that it was possible to develop handmade paper

bags and cloth bags as alternative to polybags while composite containers and metal

containers were found possible to be developed for replacing plastic root-trainers. A flow

chart of the methodology and experiments, adopted in the present study, is given on the next

page for easy understanding of the overall research. All important results and findings of the

present study are summarized under the following headings;

Preparation and development of the alternative bags and containers

Results of the experiments with selected alternatives

Conclusions

5.1.1 Preparation and Development of Alternative Bags and Containers

In the trial experiments it was found that it was possible to develop alternatives with

the naturally occurring materials while ensuring the ability of these articles to stand in the

moist soil environment where regular watering of plants is essential. Degradation by fungus

was a challenge of great consideration that was reducing the standing life/performance of bags

in the nursery. It was found that naturally occurring adhesives and glues could not stand

against the water application and moist soil. After different treatments of waterproofing agents

and fungicides, styrene butadiene latex was found suitable for waterproofing purpose and


Selection of raw material

Comprehensive Experiments with Selected Developed Alternative

Bags & Containers/Root-trainers

(Objectives 2, 3 & 4)

Waterproofing /fungicide/

thickness/shape/design/volume

Effect on seedling growth

(one legume and one non-legume tree species)

Makings of the sub-types of the finally selected types of alternative/eco-friendly

bags/containers/root-trainers

Physical testing in lab

and

nursery trials

Development of selected types of Bags/Containers

Assay of economic viability

Trials of making of alternative bags and containers

1.Evaluation of porosity,absorptiveness & water losstendency

2.Estimation of decomposition

3.Assay of carbon and nitrogen

Preparation and Development of Alternative Bags & Containers

(Objective 1)

DOCUMENTATION

FLOW CHART OF METHODOLOGY AND EXPERIMENTS


copper-sulphate was selected as fungicide. Using different combinations of these two, it could

be possible to develop handmade paper bags and cloth bags as alternatives to polybags. On the

other side, trials for development composite containers and metal root-trainers were also

carried out to make them suitable as the alternatives of plastic root-trainers (Chapter4, heading

4.1.1). The summary of trail experiment for preparation and development of all these four type

of alternatives is given below;

5.1.1.1. Preparation and development of paper bags

It was found that paper sheet, made of only waste paper pulp could not serve the

purpose hence paper pulp was blended with cotton linter pulp to increase the strength and

folding without crack. The most suitable ratio of waste paper pulp to the cotton linter was

found 30:70 to prepare 200 GSM handmade paper sheet with require strength and ease of

folding without cracks. This sheet was given waterproofing treatments using styrene butadiene

latex (SBR) and copper-sulphate to check the fungus growth (Chapter 4, heading 4.1.2)

Finally, following two subtypes of the paper bags were prepared;

P1 = PP30%CL70% 200 GSM coated with 10 % copper-sulphate solution in 50% SBR

latex.

P2= PP30%CL70% 200GSM coated with 10 % copper-sulphate solution in 50% SBR

latex + one more coating of 50 % SBR latex.

5.1.1.2. Preparation and development of cloth bags

It was found that cloth bags can be made suitable for the nursery purpose with the

application of copper-sulphate as fungicide and SBR latex as waterproofing agent. When 5%

concentration of copper-sulphate solution was found insufficient to check fungal growth, 10%

solution of copper-sulphate in the 50% SBR latex was applied (Chapter 4, heading 4.1.3).

Finally, following three sub-types of the cloth bags were made for further comprehensive

studies;

B1 = Coated with 5% CuSO4 solution in 50% SBR latex.

B2 = Coated with 10% CuSO4 solution in 50 % SBR latex.

B3= Coated with 10% CuSO4 solution in 50 % SBR latex + one more coating of

50 % SBR latex.

5.1.1.3. Preparation and development of composite containers

To make biodegradable rigid containers, different compositions of paper pulp, clay,

and Lantana Camara fiber were used and the most suitable ratio of dry weights of these raw

materials was found as 2:20:1 respectively, to prepare a mouldable paste. The SBR latex was

observed as a good waterproofing agent in both cases i.e. mixed in the raw material paste and

as surface coat. It was also noted that when two coatings of 50% SBR latex were applied

instead of a single 100% SBR coat, after mixing a moderate amount of SBR latex in the paste,

more rigidity and water resistance were attained by the container without cracks on the surface


(Chapter 4, heading 4.1.4). Following three subtypes of composite containers were prepared

for the further comprehensive studies;

C1 = Mixture + coating twice with 50 % SBR latex

C2 = (Mixture + 15 ml SBR latex mixed to each making) + coating twice with 50 %

SBR latex

C3 = (Mixture + 30 ml SBR latex mixed to each making) + coating twice with 50 %

SBR latex.

5.1.1.4. Preparation and development of metal root-trainers

Metal containers in conical shape were made from aluminum and galvanized iron

sheets and observed for the response of seedling growth. On the basis of observations

‘Galvanized Iron’ sheets of 0.30 mm thickness was selected to make the root-trainers (Chapter

4 heading 4.1.5).These two types of the metal root-trainers were designed for further studies;

MC = Round cone shaped with ribs inside.

MR = Rectangular cone shaped with ribs inside

5.1.2 Results of Experiments with Selected Alternatives

As per the above description, finally these four types (total 10 subtypes) of the

ecofriendly nursery bags and containers/root-trainers were prepared in required number and

examined for their performance and characteristics. Results of these comprehensive

experiments are discussed hereafter.

5.1.2.1. Observation of Porosity, Absorptiveness and Water Loss Tendency

Only subtypes of the cloth bags were found highly porous among all types of the bags

and containers. Double coating of SBR latex on the subtype B3 reduced the porosity value in

comparison with B1 and B2. The SBR coating also reduced porosity value to nil for both

subtypes of paper bags and all three subtypes of composite containers. Polybags, plastic root

trainer and metal root-trainers did not indicate any porosity with this test.

Nil value of absorptiveness were recorded for polybags, plastic root trainer and metal

root-trainers but Paper bags, cloth bags and composite containers showed absorption tendency

that reduced with the intensity of coating/mixing of water proofing agent i.e SBR Latex

(Chapter 4 table 4.9)

Water loss per day was found highest in the cloth bags among all type of bags and

containers for every season. The increasing order of % water loss for all bags comes as PE <

P2 ≈ P1 < B3 ≤ B2 ≈ B1. Polybags (PE) showed least vaporization due to hydrophobic

surface and do not allow water to evaporate. P1 showed slightly more evaporation than P2 due

to single coating of SBR latex. B1 and B2 showed almost equal but more evaporation than B3

because B1 and B2 had only single coat and B3 possessed double coating. (Chapter4, heading

4.2.4). The increasing order of evaporation was found as R < MR ≈ MC < C3 ≈ C2 ≤ C1 in

case of containers/root-trainers. Plastic root-trainer (R) showed minimum water loss in all the


containers. Both the metal root-trainers (MR and MC) showed similar but more evaporation

than that of plastic root-trainer (R). Sub-types of the composite containers loosed more water

among all the containers and increasing order of the degree of water evaporation was noted as

C3 < C2 < C1 that shows the inverse relation in the waterproofing agent quantity and the

degree of evaporation (Chapter 4, heading 4.2.1).

5.1.2.2. Strength (soil weight carrying capacity) of the developed articles

In the case of paper bags both the subtypes were found able to carry the wet of water

saturated soil in the laboratory transfer test but in the nursery observation subtype P2 was

found more stable in comparison with subtype P1 due to one more coating of waterproofing

agent. Cloth bags subtypes also did not show any damage or rapture in the laboratory transfer

test but bottoms of cloth bags subtype B1 and B2 were found to be ruptured in 8 and 9 months

due to fungus attack where as bottom of subtype B3 were lasted up 12 months in most of the

cases (Chapter 4, heading 4.2.2). Composite container subtype C1 that was found weakened

after 11 months. Some composite containers of subtype C2 were also showed cracked in their

bottom while evacuating the plants after 12 month. On the other hand Plastic root trainers, C3

subtype of composite containers and both subtype of the metal root-trainers were not found

with any damage or physical change in the duration of nursery experiment and found suitable

for reusing. (Chapter 4, heading 4.2.2).

5.1.2.3. Decomposition of developed alternatives

In both conditions (on-ground and under-ground) the polyethylene bags, plastic root-

trainers and metal root-trainers showed almost nil weight-loss (Chapter4, heading 4.2.3). On

the other hand, the developed cloth/paper bags and composite containers showed a weight loss

with the time and recorded higher in the under-ground conditions than the on-ground

conditions. At the subtype level, decomposition of bags was found to be affected by the SBR

strength and copper-sulphate concentration. The decreasing order of the degree of

decomposition for bags was observed as B1>B2>P1>B3>P2>PE. In case of paper bags

maximum decomposition was recorded in the subtype P1 in the under-ground condition was

62.45% and for subtype P2 was 53.06%. In case of cloth bags maximum decomposition was

recorded in the subtype B1 in the under-ground condition is 82.33% and the subtype B3

showed 57.23% decomposition that is more than 50% loss of mass in a period of 12 months.

The rate of the degradation of composite containers was more in the under-ground

experiments in comparison to the on-ground test and was found inversely proportional to the

SBR content applied (also noted in the case of bags). The increasing order of decomposition

was noted as C3 < C2 < C1 (Chapter4, heading 4.2.3). These composite containers was found

to be degraded upto a maximum weight loss of 42.30 % (in case of C1) to minimum loss of

12.89 % (in case of C3) in the under-ground conditions after 12 months.


5.1.2.4. Carbon and nitrogen content in developed alternatives

Initial amount of total organic carbon in paper bags ranges from 43.22% to 46.72 %

and 49.40% to 52 % in cloth bags whereas in case of composite containers carbon ranges from

6.49 % to 10.75%. On the other hand, the nitrogen was estimated initially around 0.16% in

paper bags and around 0.12% in cloth bags and around 0.18 % in composite containers which

is almost similar on the subtype level and showed an increasing trend initially with a slow rate

and was found almost stable after 8 months and 12 months decomposition. It was also

observed that C/N ratio decreased with a faster rate initially and this rate slowed down with

the time. (Chapter4, heading 4.2.3).

5.1.2.5. Effect on seedlings growth

All the bags/root-trainers have been tested for the seedlings growth performance

(Chapter4, heading 4.3) with two type of tree species one is non-legume i.e. Eucalyptus

tereticornis (Family-Myrtaceae) and another one is legume i.e. Dalbergia sissoo (Family-

Papilionaceae). The important facts that were found in this experiment are summarized below

separately for bags and containers/root-trainers.

5.1.2.5 (i) Effect of type of bags on the seedling growth

In case bags, root parameters i.e. primary root length, av. secondary root length and

root dry weight were found significantly different in statistical analysis in most of the

observations for both the species (E. tereticornis and D. sissoo seedlings) whereas in case of

shoot parameters three parameters i.e. shoot height, total leaf area and shoot dry weight

showed significant difference only in some observations (Chapter 4, heading 4.3.3).

Primary root length and av. secondary root length were found longest in the

polyethylene bags. Both the subtypes of paper bags i.e. P1 and P2 are showing almost same

growth of primary and secondary root length and slightly less than that of the polybags (PE)

and more than the cloth bags while in cloth bag sub-types i.e. B1, B2 and B3 the length of the

primary and secondary roots was recorded least. Same pattern also observed for the root dry

weights for both the species. Most of the time the decreasing order for the primary root length

and the secondary root length was found to be PE > P2 ≥ P1 > B3 > B1 > B2. The same

decreasing trend is also recorded for root dry weights.

The above mentioned results took placed under the influence of these most probable

factors i.e. ‘air induced root pruning’ and ‘cooper induced root pruning’ that are controlled by

‘SBR latex application’. SBR latex reduced the cloth porosity and stabilized the copper-

sulphate hence tended to minimize the effect of both; air root pruning and copper-sulphate

treatment. In case of cloth subtype B1and B2 the concentration of the SBR latex was same but

B1 was having less quantity of the copper-sulphate (5%) than the B2 (10%) hence more root

elongation (less root pruning) due to the less copper content was recorded in B1. In the case of

the subtype B3 the cooper sulphate concentration was same as B2 (10%) but one more coating

of SBR latex in B3 suppressed the copper-sulphate effect thus again less root pruning have


taken place. In addition to this, second coating has reduced the porosity in subtype B3 hence a

slightly higher length profile was recorded in this case in comparison of the other two

treatments of the cloth bags. In sub-types of paper bags (P1 and P2), primary and secondary

root length was recorded more in P2. The reason can be understood with the coating pattern as

in case of P2 the second coating of the latex suppressed the effect of copper-sulphate that was

mixed in first coating (Chapter 4, heading 4.3.3). Whereas, Longest primary and secondary

roots were found in polybag (PE) with root coiling/spiraling due to uncontrolled root growth

as these polybags neither had copper-sulphate treatment or air root pruning facility. Some ‘L’

and ‘J’ shaped roots were also observed in paper bags and cloth bags but no root coiling was

observed in the present study.

On the other hand, in the present study the difference in the shoot parameters was not

found significant in most of the cases but the root growth patterns influenced by the

type/treatment of the bag also casted a reflection on the shoot growth parameters. Most

importantly, the difference in the mean values of the shoot parameters and also in shoot-root

dry weight ratio was found non-significant in statistical analysis (except in few random cases).

It indicates that there was a similar balance in the growth of the all seedlings grown in cloth,

paper and polyethylene bags for both species.

5.1.2.5 (ii) Effect of type of containers/root-trainers on the seedling growth

Seedlings of both the species (E. tereticornis and D. sissoo) that were grown in the

subtypes of the composite containers showed more values for all shoot & root parameters than

that of the plastic root-trainers and metal roots-trainers (Chapter 4, heading 4.3.6). In the

homogenous grouping subtypes of composite container (C1, C2 & C3) are making a separate

group while the metal root-trainers (MR and MC) are making separate groups with plastic

root-trainers (R) for almost all the parameters that was found affected significantly. Hence

based on the similarity of the growth performance (homogeneity test) an increasing order can

be established for the all growth parameters as; MC ≈ MR ≤ R < C1 ≤ C2 ≤ C3.

Primary and secondary roots in the composite containers (C1, C2 & C3) grew much

longer in comparison with plastic root-trainer (R) and metal root-trainers (MR & MC) due to

the lack of air root pruning facility (wide exit hole in the bottom) and inner wall ribs in the

composite containers hence roots grew in uncontrolled manner that also increased the degree

of root coiling in composite containers. As per this reason root dry weights were also more in

the composite container sub-types. The wide pore at the end of the bottom in the plastic root-

trainers (R) and metal-trainers (MR & MC) let the roots come little out from it and roots got

pruned itself as they came in the direct contact of air, hence did not grow in length outside the

bottom.

As design of the containers affected the plant root growth pattern directly, in turn it

also casted the difference indirectly on the aerial parts of the seedlings growth parameters.

Seedlings in composite containers were recorded with more height than metal and plastic root-


trainers, these longer plants also showed comparatively more leaf area and in turn more

biomass was also observed. Further, No marked difference was observed in the shoot to root

dry weight ratio in most of the cases (Chapter 4, heading 4.3.6). It indicates that the types of

the containers do not affect the balance of plant growth irrespective of the design/treatment.

5.1.2.6. Assay of economic viability of developed alternatives

Economical viability analysis of the developed alternatives was carried out in terms of

the approximate cost of these bags and containers on the basis of the cost of the raw material

used, energy and labor input in the laboratory experiments (Chapter 4, heading 4.4). The

evaluated approximately cost of the developed alternative bags/containers/root-trainers have

been summarized in the given table with the cost of the polybags and plastic root-trainers for

the comparison.

Type of bags Estimated

cost/piece

Type of Container Estimated

cost/ piece

Polyethylene bags 0.50 ` Plastic root-trainers 15.00 `

Paper bags 1.20 ` Metal root-trainers 12.66 `

Cloth bags 2.00 ` Composite containers 4.00 `

The developed paper bags stands costly twice than the polybags and developed cloth

bags were estimated about four-times costly. Whereas In case of the composite containers and

metal root-trainers, the costs are very comparable with the conventional plastic root-trainers.

This assay the cost is estimated on the basis of the cost of the raw material that was consumed

in the laboratory level making /development of these articles. This cost difference can be

minimized very effectively at large scale production of these alternatives (Chapter 4, heading

4.4).

5.2. CONCLUSIONS

Present research led to following important conclusions with special reference to the

raw materials, fungicides, water-proofing agents and the properties of developed substitutes:

5.2.1. Important facts regarding the raw materials used

1. Most of the materials used in the study were natural and of plant origin used for bag

alternatives while clay and galvanized iron sheet were used to develop alternative

containers/root-trainers besides waterproofing agents and fungicide were also applied

to check the rate of degradation.

2. Raw materials used in the preparation of paper bags were waste paper pulp and cotton

linter (waste cotton cuttings). This preparation was based on the principle of recycling

of paper and cotton waste and thus does not involve any fresh tree felling or biomass

extraction (a cause environmental imbalance). In cloth bags, fresh cotton cloth (natural

fiber of cellulose polymer) were used thus it is ecofriendly.


3. Materials used in composite containers were natural and of low cost i.e. waste paper

pulp, clay and lantana fiber. It also involves reuse and recycling of the waste in the

form of paper pulp. The use of fiber from Lantana camara species is supposed of very

low cost and utilization of this invasive species will also check its encroaching threat.

4. The galvanized iron metal sheet was found easy to be developed in any design, shape

and volume. Metal may seem costly initially but container or root-trainers made by it

could be reused periodically over a number of years unusable they can be recycled that

further reduces the overall effective cost.

5.2.2. Effect of waterproofing agents

1. The selected waterproofing agent i.e. styrene butadiene latex (SBR), a synthetic

compound, available in the market and was found suitable because of following facts;

(a) It is colorless and transparent after curing. (b) It does not produce any kind of

smell. (c) It is water soluble before application hence different desirable concentration

can be made in water. (d) It is easy to be applied and gives a uniform coating on the

applied surface. (e) When copper-sulphate solution was made directly in this latex the

properties of this latex did not altered. (f) No negative effect on the plants was

observed after its application.

2. As an important fact it was seen in the preliminary experiments that if fungicide was

not applied with SBR latex then fungus appeared on it and slowly degraded the

surface. Thus, this latex was found non-toxic towards flora and degradable biologically

as well.

5.2.3. Effect of the fungicide used

1. Copper-sulphate was found very effective as suitable fungicide.

2. Copper-sulphate could be mixed with waterproofing agent (SBR) without interfering

with properties of the latex. The mixing with waterproofing agent avoids leaching of

this salt. Thus fungicide fixed and became durable for a longer period. It also save the

time and labour cost as the waterproofing agent and fungicide are applied in a single

stretch.

3. Copper-sulphate was found as a good root pruning agent in case of its treated cloth and

paper bags as its application reduced root coiling in these bags. Hence, it is an

additional advantage of the use of copper-sulphate besides its fungicidal property.

4. Neither any toxicity nor any negative effect was observed on the plant growth upto the

10% conc. of copper-sulphate.

5.2.4. Important facts regarding the developed substitutes

1. The difference that was found in the case of the root parameters and took palace due to

the distinguish characteristics/designs/treatments given to the developed alternative

bags/containers/root-trainers. This difference in the root parameters also casted its


effect on shoot parameters and the mean values was more or less accordingly as per

the case, but in the statistical analysis, these difference was not found significant in

most of the cases for most of the shoot parameters in respect to the type of the bags or

root-trainers for both the species (one legume, other non-legume). This proves that

these developed substitutes are on par in the performance with some more advantages

i.e. less root coiling and fibrous root development. Most importantly shoot to root dry

weight ratio was also not found significantly different for most of the observations and

also supports the fact that the whole plant body of the seedlings grown in the

developed bags/containers/root-trainers grew in the same balance as in the

conventional bags/root trainers.

2. The composite containers were not molded in to the exact shape/design as that of the

PVC root-trainer i.e. facilitated with the ribs and air root pruning phenomena. Hence,

root coiling was the greatest demerit of these containers therefore these composite

containers were not refereed as root-trainers in the text. However these containers

stand with maximum growth of the seedlings among all the containers/root-trainers. It

proves that the used waterproofing agent (SBR latex) did not pose any negative impact

to the plant growth. Hence, if these composite containers can be facilitated with the

properties of the root-trainers then these can be effective substitutes.

3. However in the seedling growth observations it was discussed that the porous surface

of cloth bags able to reduce the root coiling but on the same time high water loss by

cloth bags can be taken as a drawback of these bags that demands more frequent

watering in the dry weather.

4. In the decomposition experiment, all type of the developed bags and containers (except

the metal root-trainers) were found to be degraded with time. It supports that seedlings

grown in these bags and containers can be directly planted in the field without actually

removing the bags as in case of polybags.

5. The cost analysis of the material, used in the laboratory scale preparation, shows that

these developed bags/containers can be economically competent to the conventional

nursery polybags and plastic root-trainers if cost effectively be reduced on mass scale

production. On the other hand the environmental benefits rendered by these

alternatives should always be taken into the account at first.

Finally, it is concluded that the development of the economically feasible

ecofriendly substitutes is possible using natural materials as basic structural medium. The

concept of waste material use/recycling can also be efficiently applied in such makings to

make them more ecofriendly and cost effective. The studied substitutes did not cause any

harm to the plant growth and were found to be having distinguished properties that can also be

appreciated in the desirable fields. Outcomes of this scientific work encourage further

researches in this direction.


5.3. LIMITATIONS OF THE PRESENT STUDY

1. Styrene butadiene latex was the only synthetic latex that were tried in this research due

to the time and cost limitations. Although it was found suitable for the application,

biodegradable and non-toxic to the plants but the overall effects of this latex was not

analyzed and the disintegration of this latex or mixing of its residuals into the soil was

not examined.

2. The composite containers developed for this study were not moulded in the desired

shape and design of the root-trainers due to the limitations of the facility, time and cost

of experiment. Hence it would be referred as the semi substitutes of the root-trainers

where it could be used as complete substitute for the polybags.

3. The seedling growth experiments were carried out only in the glass house environment.

Experiments under actual field conditions were not undertaken to validate the results.

4. The cost analysis was based on the cost of the material that used in the laboratory level

in the development/experiment of these alternatives and any of the proper economics

methodology could not be followed so that the real effective cost could be evaluated

while considering the environmental benefits and other additional qualities of these

containers.

5.4. RECOMMENDATIONS

Long term experiments with selected alternatives should be undertaken to monitor the

seedling growth, both under nursery and field conditions, before recommending extensive use

of these alternatives.

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