Water dynamics in crop plants under environmental stress conditions

利用热平衡树液流法研究了环境胁迫条件下作物体内包括逆流在内的水分动态。本研究以长柄田菁、芒果(欧文)和苹果(灿烂)为试材。研究结果如下：1.重新设计了热平衡液流传感器，用于测量植物根部和花序梗中的液流。2.在田菁中，如果部分根区干燥，导致根系不活跃，“干”根白天吸收水分的减少可以用“湿”根来补偿。利用液流传感器可以在夜间直接观察到干根中的逆流。3.表明在干根区土壤干燥过程中，新根在湿根区迅速生长，湿根吸收水分的能力增强。4.芒果花在清晨获得了大量的水分供应，这归因于茎中的储水。在芒果果梗中，上午观察到水分从果实到枝条的逆流。树干和树根的液流之间几乎没有时间滞后，表明两者之间具有较高的导水率。在苹果树上，我们的实验表明，苹果树的主要储存元素是树冠。我们的研究为深入了解作物体内的水分动态提供了更深入的了解，这是开发利用作物的能力来减轻其水分胁迫、更有效地管理农业用地上的水分可持续利用以及生产更高质量的果实所必需的。

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.