Effects of hydraulic lift on growth of neighboring crop

液压抬升是指水通过植物根系从深层潮湿土层进入较干燥的上层土层。有人认为，液压提升导致干层土壤水分的增加可能对植物本身和/或其邻居有益。然而，这种可能的优势鲜有文献记载。在本研究中，进行了劈裂根实验，以检测液压升降机并找到对邻居的好处。首先，采用垂直桩状根管，展示了豌豆根系与湿润土壤的深层桥接，在不浇水的浅根区保持土壤有效水分的功能。在不灌溉和不受水分胁迫的情况下，鸽豆可以保存上层土壤的水分，这使得我们假设在干旱条件下，鸽豆可以从深层土壤中吸收足够的水分来保存表层土壤的水分。其次，采用直径1 m的平底锅作为表层土层，研究液压举升对周边作物的影响；Markhamia种植在地面上的盆中，但其主根可以深入地下。盘面西侧长有几根侧根。西侧和东侧种植旱稻（无侧根）。随着锅内土壤的干燥，树木与水稻植株之间首先在根侧发生水分竞争，侧根侧植株的气孔导度低于无侧根侧植株。土壤较干时则相反，无侧根侧的水稻植株枯萎，而侧根侧的水稻植株保持绿色。本研究发现，当表层土壤干燥时，液压举升能够改善邻近植物的水分状况

Hydraulic lift refers to the movement of water from deep wet soil layers into the drier upper horizons through plant root systems. It has been suggested that increases in soil moisture in the dry layer resulting from hydraulic lift may provide benefits to the plant itself and/or tp neighbours. However, this possible advantage is poorly documented. In this study, split root experiments were conducted to detect hydraulic lift and to find benefits to neighbours. Firstly, vertically staked sprit-root tubes were applied to show a pigeon pea root system, bridged to a moist soil in depth, function to maintain available soil water in non-watered shallow root zone. The pigeon pea saved the soil moisture of the upper layer under no irrigation and continued transpiration without water stress, this leaded to the assumption that pigeon pea can perform a sufficient water uptake from deep soil to save water in surface soil layer under drought conditions. Secondly, a pan of 1 m in diameter was used as a surface soil layer to study effect of hydraulic lift on neighboring crop. Markhamia was planted in the pan located on the ground, but its main root could penetrate into the ground. Several lateral roots grew in west side of the pan. Upland rice was planted in the west side and east side (no lateral roots). As the soil in the pan dried, water competition first occurred between the tree and rice plants in the root side, and stomatal conductance of the plants in the lateral root side was lower than that in no lateral root side. When the soil was drier, reverse occurred, and the rice plants in no lateral root side wilted, while the rice plants in the lateral root side kept green. In this study, it was found that hydraulic lift enable to improve water status of neighboring plants when surface soil layer dries