Soybean seeds show high sensitivity to climatic conditions and to management before and during harvesting. In the crop season 1997/1998, the "El Niño" phenomenon produced copious rains causing seed damage. The aim of this study was to evaluate the differential germination response between soybean seeds harvested on time and seeds submitted to weathering, and to verify the possible existence of genetic variability in germination of deteriorated seeds. Twenty varieties belonging to Maturation Group III were studied. From each variety, two seed lots were processed: seed harvested on time, under favorable agro climatic conditions ("good"), and seed deteriorated by a long permanence in the field before harvesting ("bad"). The germination, Tetrazolium tests and conductivity for viability and vigor analysis, and a field emergence test were carried out. In "good" seed lots, germination attained the highest values (between 70 and 80%) only in 55% of varieties and vigor ranged between 32% and 67% and seedling emergence between 31% and 49 %. Vigor by the Tetrazolium test showed the best relationship with field emergence. There was significant correlation among all tests. "Bad" seed lots presented very low germination (2-27%). No variability was detected in the germination behavior of different varieties in relation to unfavorable harvest conditions.
seed; soybean; germination; viability; vigor
