The Influence of Genotype, Temperature and Moisture on Seed Longevity in Chickpea, Cowpea and Soya bean

Seed of three chickpea (Cicer arietinum L.), three cowpea [Vignaunguiculata (L.) Walp.] and four soya bean [Glycine max (L.)Merr.] cultivars were hermetically stored for up to 2 yearsin various constant environments which included temperaturesfrom —20 to 70 °C and moisture contents (fresh weightbasis) from 5 to 25 per cent. In all cases the survival curvescould be described by negative cumulative normal distributions.The longevity of the various seed lots differed but the valueof the standard deviation (the reciprocal of which gives theslope of the survival curve when percentage germination is transformedto probit) was the same for all cultivars within a species whenstored under similar conditions. Within each species the relativeeffects of moisture and temperature on longevity did not differsignificantly between cultivars. In all three species therewas a negative logarithmic relationship between seed moisturecontent and longevity, but the relative effect of moisture contentdiffered between the species: differences in the longevity ofsoya bean seed as a function of moisture content were less thanfor either cowpea or chickpea. The relative effect of temperatureon seed longevity did not differ between the three species,and the seed of all three species showed increasing temperaturecoefficients for the change in rate of loss of viability withincrease in temperature. The complete pattern of loss in viabilityin all three species can be described by a single equation whichwas developed for barley and has also been shown to apply toonion seed. The constants applicable to the three grain legumeshave been calculated so that it is now possible to predict percentageviability of any seed lot of these species after any storageperiod under a very wide range of storage conditions. Cicer arietinum L., chickpea, Glycine max (L.) Merr., soya bean, Vigna unguiculata (L.) Walp., cowpea, seed longevity, seed storage, moisture content, temperature