Water dynamics in crop plants under environmental stress conditions

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Water dynamics including reverse flow in crop plants under environmental stress conditions was examined using heat balance sap flow method. Sesbania rostrata, mango (cv.Irwin) and apple (cv.Splendor) were used for this study. The results are summarized as follows :1.Heat balance sap flow sensor was redesigned for measuring sap flow in roots and peduncles of plants.2.In Sesbania rostrata if part of root zone dries and as a result the roots become inactive, a decrease in daytime water uptake by the "dry" roots can be compensated by "wet" roots. Reverse flow in the dry root was directly observed at night using the sap flow sensor.3.It was suggested that new roots grew rapidly in the wet root zone during soil drying in the dry root zone and the wet roots became more active in its uptake of water.4.Mango flowers were supplied substantial water early in the morning ascribed to stored water in the stem. In the peduncle of mango fruit, reverse flow which refers to the movement of water from fruit to shoot was observed in the morning. Water flew into fruit in the nighttime.5.There was little time lag between sap flow in the trunk and the root of the apple tree, suggesting a high hydraulic conductivity between them. In apple tree, it appeared here in our experiment that the main storage element of the apple tree was the crown.Our study provided deeper understanding of water dynamics in the crop plants which is needed to develop technologies for using the ability of crop to reduce its water stress and for more efficient management for sustainable use of water on agricultural land, and to produce fruits of better quality.