Published online by Cambridge University Press: 27 March 2009
Field experiments were made in both 1974 rainy seasons in Ibadan, Nigeria, to evaluate the effect of harvest time on seed quality and viability of soya beans (Glycine max (L.) Merr.). The first harvest was made when about 85% of the pods had ripened and subsequent harvests were made at 7-day intervals. Delaying harvest increased the percentage purple-stained, cracked and black seeds in the first season, and of cracked seed in the second season. In the second season soya-bean seeds showed neither purpling nor dark discoloration on the seed coat; the crop matured during sunny, dry weather. However, in both seasons the reduction in seed quality was accompanied by a corresponding decrease in germination percentage. Varietal differences were noted in that the small-seeded Improved Pelican was least affected, and Hardee was the most affected by field weathering in both seasons. Kent and Bossier were intermediate between the two extremes. The results point out the importance of proper timing of harvest of soya beans in rainy seasons, and the need for screening soya beans for resistance to weathering in the tropics.