Heat tolerance in grain legumes

In this work the effect of high germination temperature has been investigated on seed quality of soybean cultivars; and bean genotypes grown under irrigated and non-irrigated, dry conditions. After four and eight days we expressed the degree of drought tolerance by the rate of abnormal and diseased seedlings. The high temperature significantly increased the number of abnormal seedlings, which come from seeds of both species grown under non-irrigated, dry conditions. The chemical substances and root development of seedlings from bean, soybean and pea grown under non-irrigated condition were investigated at 20/10 degrees C as control temperature 25/25 degrees C (day/night) and 30/30 degrees C (day/night). Moderate heat stress (25/25 degrees C) caused considerable decrease in root length of seedlings from large seeded bean genotypes but did not in soybean cultivars. Rising temperature did not change the protein contents of shoot in either species but increased the dry matter significantly except the pea. At 25/25 degrees C the fat content of shoot in all legume seedlings decreased slightly compared to the control but it increased again at 30/30 degrees C. We did not find correlation between the fat content of root and the reaction of genotypes to heat stress. The rate of abnormal seedlings and the distribution of primary root length expressed the tolerance of genotypes to heat stress. At the early stage of germination the selection to improve heat tolerance in only beans could be achieved at high temperature.