Jbf. Neto et al., SOYBEAN SEED QUALITY AS AFFECTED BY SHRIVELING DUE TO HEAT AND DROUGHT STRESSES DURING SEED FILLING, Seed science and technology, 21(1), 1993, pp. 107-116
A high level of shriveled soybean (Glycine max (L.) Merrill) seeds was
reported in several regions in Brazil in 1990. The occurrence of shri
veled soybean seeds is also reported in some areas in the U.S.A. This
problem is observed in Florida (USA) and Parana (Brazil) almost annual
ly. The occurrence of shriveling means losses to the producers of soyb
ean seed and grain. Shriveling results from the occurrence of heat (ai
r temperature above 30-degrees-C) and drought stresses during seed fil
l. These stresses may result in 100% shriveled seeds in some cultivars
, such as 'Bragg'. The objectives of these experiments were: a) to det
ermine the effects of different levels of shriveling on the quality of
soybean seeds; and b) to determine the critical level of shriveling t
hat can be accepted in a seed lot without reducing its quality. Two ge
notypes were studied: 'Forrest,' produced in Gainesville in 1987, and
the breeding line BRAS 85-1821, produced in Londrina in 1989. Seed sam
ples were prepared with different levels of shriveling from 0 to 100%.
Dry weight (g/100 seeds) decreased as shriveling increased. Seed qual
ity, determined using germination, tetrazolium (vigor and viability),
blotter, and emergence in sand tests, was significantly reduced as the
level of shriveling increased. The reduction in quality was greater f
or seeds of Forrest because the plants were subjected to high temperat
ure and rainfall during maturation. The distribution of shriveling wit
hin a soybean plant varies, the incidence of shriveled seed from the u
pper third of the plant exhibiting the highest levels of shriveled see
d. The observed trends for reduction in seed quality due to shriveling
were similar for the studied parameters despite the effects of differ
ent genotypes and production sites.