Seed quality enhancement in cowpea (Vigna unguiculata (L.) Walp.) by film coating technique
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Date
2010
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Department Of Olericulture, College Of Horticulture, Vellanikkara
Abstract
Film coating is the latest seed coating technique adopted for application of protectants, nutrients and growth regulators onto the seed. The study on “Seed quality enhancement in cowpea (Vigna unguiculata (L.) Walp.) by film coating technique” was undertaken in the Department of Olericulture, College of Horticulture, Kerala Agricultural University with the objective of standardising the dose and method of film coating, studying the effect of film coating in combination with insecticides, fungicides and bio agents on seed quality during storage and also to study the effect of seed film coating on growth, field performance and yield of cowpea.
Results revealed that film coating the seed @ 20ml.kg-1 seed gave good colour, lustre and uniform coating over the seed. With respect to germination parameters, T4 (20ml.kg-1 seed) and T8 (20ml.kg-1 seed) were found to be the best treatments recording maximum values for germination (88 per cent and 85 per cent). The speed of germination, ranged from 51.35 (T6) to 57.72 (T7) and there was no significant difference between the treatments. With respect to days for 50% germination there was no significant difference between treatments. Seedling lengths (root + shoot) and vigour indices were the highest in T4 (34.49cm and 3125) and T8 (35.59cm and 3010) of dry and wet method of seed treatment.
These two treatments T4 (dry) and T8 (wet) were used to study the effect of seed film coating in combination with insecticides, fungicides and bio agents on seed quality during storage. Irrespective of the methods followed, all the treatments showed a decrease in germination, speed of germination, seedling length and vigour indices with an increase in the storage period. In dry method of seed coating, in all the treatments seeds were viable even after one year of storage although the germination per cent was below the minimum standard for seed certification. Results of the storage study indicated the superiority of T5 (Pseudomonas 10g.kg-1 seed) and T4 (Trichoderma 4g.kg-1 seed) where bio agents were used for seed coating with highest values of germination and vigour. In T5, the germination percentage decreased from 96 to 86 % in dry method and from 95 to 87% in wet method at 0 and 9 months of storage respectively. The speed of germination decreased with increase in storage period ranging from 58.95 to 29.35 in dry method of film coating and 51.73 to 4.63 in wet method of film coating. Vigour index-1 values were high in T4 and T5 (> 3400) during 0th month storage and it decreased considerably with increase in storage period. Treated seeds were free from pest attack throughout the storage period. Attack of pulse beetle (Callosobruchus chinensis) was noticed in the stored seeds in later stage in untreated control of dry method. No incidence of fungal attack was noticed throughout the storage period.
Biochemical studies conducted in stored seeds revealed an increase in values of electrical conductivity of the leachate, lower the leachate value higher will be the vigour of seeds. Decrease in seed protein content and activity of dehydrogenase enzyme with increase in storage period indicated the loss of vigour in stored seeds. Seeds coated with Pseudomonas @10 g per kg seed (T5) followed by seed treatment with Trichoderma @ 4g per kg seed (T4) were best with respect to maintaining viability and vigour of the seeds throughout the storage period as compared to controls (film coated and untreated).
Film coated seeds were planted in the field to study their field performance, growth, yield, pests and disease incidence etc. Under field condition, germination was more than 95 per cent in seeds treated with Pseudomonas. In both wet and dry methods of treatment, seeds coated with bio-agents performed better over other treatments with respect to parameters viz., field germination, number of fruits, fruit length, average fruit weight and yield. Fruit yield per plant and plot yield were highest in seeds coated with bio agents like Pseudomonas and Trichoderma having a value of 3.27kg and 3.85kg per 2.7m2 as compared to untreated control having a value of (1.27 and 1.81kg per 2.7m2). Under field condition, seeds treated with chemicals gave maximum protection against pest and diseases whereas highest incidence of pest and diseases were noticed in untreated seeds.
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