植物对土壤水分变化的响应与控制性分根交替灌溉

Response of Plants to the Change of Soil Moisture Content and the Controlled Alternative Partial Root-zone Irrigation

在土壤水分减少的情况下 ,植物可以感知并利用脱落酸 (ABA)作物信号传递物质 ,将水分胁迫信号传至叶片 ,进而调节气孔导度 ,减少蒸腾耗水。同时 ,植物蒸腾耗水与气孔导度为线性关系 ,而光合作用与气孔导度为渐趋饱和关系 ,如果适当降低气孔导度 ,可以在显著降低蒸腾耗水的基础上 ,对光合没有影响或影响很小。在此理论基础上 ,提出了一种新的灌溉技术———控制性分根交替灌溉。其核心是通过一定的灌溉措施 ,形成土壤水分的不均匀分布 ,使作物的根系处于不同的水分状态 :处于湿润部分的根系吸收水分 ,保证作物光合 ,处于干燥土壤的根系产生ABA ,调节叶片气孔导度。这样 ,在不降低或少量降低光合作用的前提下 ,更多地减少作物的蒸腾耗水 ,提高作物的水分利用率。它是一种以内涵为主的节水灌溉技术 ,具有坚实的理论基础和良好的应用前景。

Under the conditions of decreasing soil moisture content, plants can sense it and send the message of moisture stress to their leaves by ABA to reduce the plant transpiration by regulating the stomatal conductance of leaves. Moreover, there is a linear correlation between the plant transpiration and the stomatal conductance of plant leaves, whereas there is a tending-saturation correlation between the plant photosynthesis and the stomatal conductance of plant leaves. If the stomatal conductance of plant leaves is suitably reduced, there is no or only a little influence on plant photosynthesis based on effectively reducing plant transpiration. A new irrigation way, controlled alternative partial root-zone irrigation, is proposed based on the theoretical background above. The way is to irrigate partial root-zone for forming an asymmetrical soil moisture distribution, thus the roots in wetted zone can suck up moisture to maintain plant photosynthesis, while the roots in dry-zone can regulate the stomatal conductance by ABA. Thus, the plant transpiration can be reduced and the soil moisture can be fully sucked up by plants under the conditions that the photosynthesis of plants is not reduced.