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通过挖掘法,研究了膜下滴灌不同生育期棉花根系形态特征和生物量分配对不同水氮的响应。结果表明:花铃期,正常灌水促进了根系和地上部的生长,根、地上部干重、根表面积指数、平均根长密度显著增加,根冠比下降。无论灌水量如何,施氮促进了根系和地上部的生长,但对地上部的促进作用远大于根系,表现为根冠比下降。吐絮期,在低氮条件下,灌水量增加,根干重、地上部干重显著增加。在中氮和高氮条件下,不同的灌水量对根干重没有影响。无论施氮量如何,灌水量增加,平均根长密度、根表面积指数显著下降,地上部干重明显增加,根冠比下降。水分胁迫时,中氮的根干重明显高于低氮和高氮处理,而施氮对地上部干重,平均根长密度的影响不明显,根表面积有降低的趋势。正常灌水时,施氮量增加,根干重、根长密度、根表面积指数显著降低,地上部干重以中氮水平最高。花铃期至吐絮期,根干重随生育期的延长明显增加。水分胁迫条件下,平均根长密度、根表面积指数随生育期的延长有增加的趋势。正常灌水条件下,平均根长密度、根表面积指数随生育期的延长下降。
Through the digging method, the responses of morphological characteristics and biomass allocation of cotton roots under different drip irrigation periods to different water and nitrogen were studied. The results showed that in flowering stage, normal irrigation promoted the growth of roots and shoots, and the root and shoot dry weight, root surface area index and average root length density increased significantly, and the ratio of root to shoot decreased. Regardless of the irrigation amount, nitrogen application promoted the growth of both root and shoot, but the promotion effect on shoot was much larger than that of root. The root-shoot ratio decreased. During the boll opening period, under low nitrogen conditions, irrigation volume increased, root dry weight and shoot dry weight increased significantly. Under middle-nitrogen and high-nitrogen conditions, different irrigation amounts had no effect on root dry weight. Regardless of amount of nitrogen application, irrigation volume increased, average root length density, root surface area index decreased significantly, aboveground dry weight increased significantly, root-shoot ratio decreased. Under water stress, the root dry weight of medium nitrogen was significantly higher than that of low nitrogen and high nitrogen, while the effect of nitrogen on root dry weight and average root length density was not obvious, and the root surface area tended to decrease. Under normal irrigation, the nitrogen application rate increased, the root dry weight, root length density and root surface area index decreased significantly, while the shoot dry weight reached the highest level. Flowering stage to boll opening stage, root dry weight increased significantly with the growth period. Under water stress, the average root length density and root surface area index increased with the extension of growth period. Under normal irrigation conditions, the average root length density and root surface area index decreased with the extension of growth period.