花期干湿交替对玉米干物质积累与再分配的影响

Effect of Soil Drying-Wetting Alternation on Dry Biomass Accumulation and Reallocation at Maize Flowering Stage

通过干湿交替处理模拟花期季节性干旱,研究了不同的土层厚度、干旱强度对不同基因型玉米干物质积累与再分配的影响。结果表明,花期严重干旱促使叶片急剧衰老,但根系发育相对稳定,以尽可能地维持茎秆正常生长,从而导致叶片(根)所贮藏干物质转移至果穗的百分率比轻度干旱增加8.48个百分点,茎秆原贮藏干物质转移至果穗的百分率减少14.68个百分点;复水后,促使严重干旱胁迫的源器官衰老短暂减缓,花后光合产物转移至果穗的百分率比轻度干旱增加6.21个百分点,花后干物质积累对产量的贡献率增大,以补偿前期干旱的损失,但是花后补偿生长不足以弥补干旱期干物质积累的减少。在不同程度的水分亏缺过程中根量和茎秆保持相对稳定,正是复水后植株补偿生长的基础,这也揭示了干湿交替对植株干物质积累的激发效应。研究还发现,不同基因型在花期不同土层厚度、不同干旱胁迫影响下复水的干物质积累速率存在显著差异,增厚土层和减轻干旱胁迫程度均有利于增强植株补偿生长的能力。因此,需要进一步研究不同土层厚度、不同生育阶段干湿交替对作物产生有益补偿生长的阈值。

This is popular by potted experiment in the drought injury test, but it cannot get the full response on drought stress and on compensation growth at maize flowering stage. To set controllable test of pool planting and canopy of drought studied on dry biomass accumulation and reallocation of maize under soil drying-wetting alternation of different soil layer and drought degree and genotype. The result showed that severe drought stress at flowering stage urged fast senescence of leaves and stable growth of root system and then maintaining growth of stem, these bring to increase the rate on stored originally substance of leaves and root system transporting to spike and to decline the rate on stored originally substance of stem transporting to spike after flowering, it was 8.48 and 14.68 percents more than the light drought. After re-watering, it was to compensate loss of drought at earlier stage that increase the rate of photosynthetic yield transporting to spike and the rate of contribution to dry biomass because of short-time slowing down on senescence of source organs, it was 6.21 percents more than the light drought. Because dry weight per plant of severe drought stress had reduced by 36.8 percents to light drought at maturity stage, compensation growth after flowering could not enough to compensate, so dry biomass accumulating decreased in severe drought stress. It was obvious that root system and stem and sheath maintain relative stabilization under water deficit on different drought degree that was a foundation of compensation growth of plant after rewatering; these reveal the compensation effect after flowering under soil drying-wetting alternation . And then studies discovered that rate of dry biomass accumulation （RDBC） on varieties after re-watering was C14 〉 C19 〉 C202, but RDBC in drought stress was C202 〉 C19 〉 C14. Therefore, the characters of compensation growth and drought resistance on genotype had difference types of representation; the variety on drought resistance and saving water at seasonal drought areahad been definite drought resistance in drought stress and the bigger effect of compensation growth after re-watering. The study adopted the varieties which were the type on drought resistance and higher compensation growth（Chengdan 19）, and the type on water sensitivity and the highest compensation growth（Chengdan 14）, and the type on drought resistance and lower compensation growth （Chengdan 202）. To add soil layer and to lighten drought degree were beneficial to enhance the ability of compensation growth. Therefore to add soil layer not only to strengthen the crop capacity of drought resistance significantly, but also to take the advantage of the potential on compensation growth. The degree of compensation growth concerns the early drought. That should do more research on the value point of soil water capacity on profitable compensation growth under soil alternate drying-wetting of different growth stage and soil layer of different crops or varieties.