02080nam a2200217 a 450000100080000000500110000800800410001910000190006024500510007926000480013030000100017850000260018852015420021465000130175665000240176965000120179365000090180565300230181465300130183765300120185011325422018-05-29       1978    bl uuuu  m   00u1 u    #d1 aMENEZES, E. A.  aSome aspects of drought resistance in soybean.  aStillwater: Oklahoma State Universityc1978  a39 p.  aDissertacao Mestrado.  aThree experiments were conducted to study the ability of soybean seedlings to withstand repeated drought cycles under controlled environmental conditions, root characteristics in relation to drought conditions, and the ability of soybean seeds to germinate and develop under different osmotic concentrations. The experimental material included 24 soybean varieties ranging from Group III to Group VII of maturity. In thefirst experiment, seedlings were grown in metal trays in a growth chamber and subjected to five sucessive cycles of droutht followed by rewatering. The results showed small reduction of plant survivors in the first two cycles, but a great loss of plants after the ghird drouthg cycle, and further losses in thefourth and fifth cycles. In the second experiment, seedlings were grown in plastic pots filled with washed sand. after 18 days in the growth chamber with adequate moisture, root wer weight, lenght, volume, and root/shoot ratio were measured. The analyses of variance showed significant varietal differences in all four characters. The most drought resistant varieties are expected to have heavier root weights, greater root volume, longer roots, and higher root/shoot ratios. In the third experiment, the seeds were germinated in six different concentrations of d-mannitol solutions. The percentage germination indicated that there was a small reduction in germination as the osmotic pressure increased. Seedling lenght decreased more markedly as the osmotic pressure increased. The varieties differed(...).  aSoybeans  aResistência a Seca  aSemente  aSoja  aDrought resistance  aSeedling  aSoybean