Internal water-relations in soybean under water deficit in field conditions

Abstract

Soybean plants (Glycine max) cv. Doko were subjected to different soil drying cycles and rewetting. Using the pressure-volume curve method, the osmotic potential at full turgor (4,7 l 00) and water potential at zero turgor (4,0) were measured. The leaf concentration of proline was also analysed. In one of the treatments (19 days without irrigation, wich corresponds to 102 days after emergence) there was a decrease in 4,ir10° and 4,0, indicating the occurrence of osmotic adjustment. The proline accumulation does not seem to participate in this mechanism. In two of the treatments a decrease of it's concentration in response to water deficit was found. On the other hand, variations among tjnr"°, 4,0 and proline concentration between the treatments that were not subjected to a soil drying cycle at different sampling dates were observed