Genotypic Variation for Three Physiological Traits Affecting Drought Tolerance in Soybean

摘要: Three physiological traits that may affect performance of soybean [Glycine max (L.) Merr.] when soil water availability is limiting are (i) use efficiency (WUE), (ii) regulation whole plant in response to content, and (iii) leaf epidermal conductance (ge) stomata closed. Six introductions (PIs), eight breeding lines derived from them, nine cultivars were compared for variability these three during vegetative growth two greenhouse studies. In the first experiment, use, normalized both size evaporative demand (the transpiration ratio, NTR), was monitored a 10-d cycle gradually increasing drought stress then an additional 2 d following rewatering. The critical content at which each began reduce its (FTSWC), determined. WUE estimated as ratio total dry weight used. second ge determined same 23 genotypes by measuring vapor exchange after 36-h dark adaptation. Substantial variation found among WUE, FTSWC, ge, also extent NTR recovered on Generally, adapted had greater lower than did PIs. However, PI 471938 progeny N98-7264 clear exceptions this trend. An unexpected finding significantly negatively correlated with across genotypes.