土壤干旱对作物生长过程和产量影响的研究进展

Advance About Impact of Soil Drying on Growth and Yield of Crops

水分短缺是作物生长中最大的限制因子,土壤干旱胁迫使植物的长势、生理机制、激素水平等都会发生一系列变化。在干旱半干旱地区,土壤水分亏缺能明显抑制作物根系和地上部生长,显著降低作物的生物量、产量和收获指数。禾谷类作物小麦(Triticum aestivum)在灌浆期遇到水分胁迫时,会引起光合速率降低、灌浆时间缩短、灌浆速率下降、植株老化提前,但是它能增加营养组织到籽粒中非结构性碳水化合物的再代谢。土壤水分和植物激素共同调控作物的灌浆过程,当遇到土壤干旱时,作物叶片、花、籽粒发育过程中植物生长调节剂ABA浓度明显增加,且ABA、乙烯、ACC等的浓度随着干旱程度而变化。植物对干旱的适应性主要表现在植物生理、形态上的改变,比如植株结构、干物质积累、植物组织渗透势、气孔导度等的变化。土壤干旱不利于植物生长,但有利于胁迫临界点的产生,这就有可能利用土壤干旱条件下在灌浆较慢时诱导整个植株衰老和更好地进行碳代谢来提高籽粒产量,如果在作物灌浆后期适度控制土壤干旱可以增加籽粒产量和收获指数,有助于农业生产中的节水,这对于发展可持续农业是迫切需要的。

Water or drought stress is one of the most important factors limiting crop growth world - wide. Some changes would be observed in plant growth, physiological mechanisms and hormone level under soil drying stress. In arid or semi - arid region, water deficit in soil evidently inhibit the root and the shoot growth, and decrease biomass, yields and harvest index. Usually, water stress during the gain - filling period would decrease photosynthesis, shorten the grain - filling period, decline the grain - filling rate and induce early senescence, however, it would increase the remetabolism of non - structural carbohydrate （NSC） from the vegetative tissues to the grain. Grain filling is an intensive transportation process regulated by soil drying and plant hormones. The concentration of ABA, which is generally regarded as an inhibitory growth hormone, would increase markedly in leaves, floral organs and developing grains in responses to soil drying. Some of the adaptive responses to drought are due to physiological and morphological changes, such as changes in plant structure, dry matter accumulation, tissue osmotic potential and stomatal conductance. Soil drying is unfavorable to plant growth but may be favourable to the critical point of producing stress. So it is possible to take advantage of soil drying to induce whole -plant senescence and better carbon remetabolism to improve grain yield during the slow grain filling period. If mild soil drying is properly controlled during the later grain -filling period in some crops such as rice （Oryza sativa） and wheat （Triticum aestivum）, it could enhance yield and harvest index, and might contribute to water saving, which is imminently needed to develop sustainable agriculture in many parts of the world.