Variability in seed quality and storability of cowpea (Vigna spp.) varieties
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Date
2015
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Department of Seed Science and Technology, College of Horticulture, Vellanikkara
Abstract
Seed is the basic input in agriculture contributing to 15-20 per cent of productivity. In most cases, it becomes essential to store seeds and therefore maintenance of seed quality during storage is inevitable. During storage, a number of physiological and biochemical changes occur in seeds which result in ageing or seed senescence. The rate at which the process of seed ageing takes place depends on the weather conditions of the storage atmosphere and the ability of seed to resist the degradative changes. Genetic makeup of the species and varieties also decide the senescence pattern.
Cowpea is an important vegetable crop of Kerala. An array of improved varieties is available for cultivation. Storage experiments were conducted with seeds of ten different varieties of cowpea (Lola, Vellayani Jyothika, Vyjayanthi, Anaswara, Kairali, Kanakamony, Kashi Kanchan, Sreya, Hridya and Bhagyalakshmi) belonging to trailing, semi trailing and bush growth habits to assess the genetic variations in seed quality parameters, seed senescence pattern and seed longevity. Seeds obtained from summer crop (February-June, 2014) were stored in polyethylene bags of 700G and observations on seed quality parameters were recorded at monthly intervals.
Results indicated that, irrespective of varieties, the seed quality parameters viz. germination, speed of germination, seedling vigour and dehydrogenase enzyme activity decreased while electrical conductivity of seed leachate and seed microflora infection per cent increased with increase in duration of storage.
Irrespective of varieties, a higher germination, speed of germination, seedling vigour and dehydrogenase enzyme activity coupled with a significant reduction of electrical conductivity of seed leachate and seed microflora infection was observed in seeds stored under cold storage (20±2ºC) compared to those stored under ambient storage condition (25-30ºC).
Among the varieties, the highest germination, speed of germination and seedling vigour index I were recorded in Kashi Kanchan followed by Kanakamony. The two varieties also retained a germination per cent of above minimum seed certification standards (75% germination) for six months of storage. The lowest germination, speed of germination and seedling vigour index I were recorded in variety Vellayani Jyothika (trailing type).
Based on growth habit, it was observed that the highest germination per cent, speed of germination, seedling vigour index I and the lowest infection of seed microflora were recorded in the semi trailing varieties followed by trailing type. The bush types were found to be on par with trailing types for the above characters.
Considering the varietal variations based on storage study, stability and cluster analysis, the varieties which retained maximum germination and quality parameters were Kashi Kanchan and Kanakamony and the varieties which shown poor performance were Vellayani Jyothika, Kairali and Hridya.
There was a high significant and positive correlation between vigour index I and speed of germination with germination per cent. Path analysis indicated significant direct effect of seedling vigour index I on germination.
Considering the seed quality parameters during storage, varieties Kashi Kanchan and Kanakamony proved to have high storage potential. These can be preferred to employ in future breeding programmes aimed towards improving seed storability.
Further studies and confirmation are required to reveal the reasons for faster senescence in seeds of varieties viz. Vellayani Jyothika, Kairali and Hridya
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