棉花花铃期短期干旱下氮素对干物质及氮素累积分配的影响

Effects of Nitrogen on the Dry Matter,Nitrogen Accumulation and Distribution of Cotton under Short-term Soil Drought during the Flowering and Boll-forming Stage

通过盆栽试验进行水分(正常灌水和干旱后复水)和施氮处理(0、240、480kgN·hm-2),研究花铃期短期干旱再复水后氮素对棉花各器官干物质重、氮素累积与分配及产量与品质的影响.结果表明:花铃期土壤干旱显著降低了棉株各器官的干物质重与氮素累积量,而增大了棉株各器官的氮素含量,同时亦降低了棉株干物质与氮素在叶片中的分配指数,但提高了在根系的分配指数,从而增大了根冠比;增施氮肥可以提高干旱条件下棉株的干物质重与氮素累积量,但亦增大水分胁迫指数.复水对干旱处理棉株生长具有明显的补偿效应,尤其是根系的干物质重与氮素累积量显著高于相应正常灌水处理,且增施氮肥可以提高棉株的补偿效应.花铃期干旱结束时与复水后第10天,干旱处理棉株均以240kgN·hm-2水平下的生殖器官干物质重与分配指数最高,而根冠比最小,地上部与地下部生长最为协调,最终籽棉产量最高、纤维品质最优;而施氮不足(0kgN·hm-2)或过量(480kgN·hm-2)均不利于棉花产量的提高与纤维品质的改善.

Effects of nitrogen on the dry matter weight, nitrogen accumulation and distribution, yield and fiber quality of cotton under short-term drought and after re-watering during flowering and boll-forming stage were studied. Pot experiments were conducted to short-term drought in 2005 and 2006 at the research field area of Nanjing Agricultural University. Within each water treatment, three nitrogen levels were imposed.0,240 and 480 kg N · hm^-2. According to data,soil drought significantly reduced dry matter weight, nitrogen accumulation,yield and fiber quality of cotton, but increased N content in different organs of cotton,compared with well-water treatments. Drought reduced the distributive indices of dry matter weight and nitrogen accumulation in leaf, but increased the distributive indices of dry matter weight and nitrogen accumulation in root,and increased the ratio of root dry matter/shoot dry matter and root N accumulation/shoot N accumulation of cotton. Nitrogen increased dry matter weight and N accumulation in cotton, and augmented the water stress indices under drought stress. There was notability compensative growth for cotton after re-watering, especially for root, the dry matter weight and nitrogen accumulation in root of drought treatments were higher than that of well-water treatments. Nitrogen could enhance the compensative capacity. The dry matter weight of reproductive organs,cotton yield and fiber quality were all highest at 240 kg N · hm^-2 level under drought and after soil re-watering. These results suggest that 240 kg N· hm^-2 is the optimal nitrogen application rate under short-term drought in our experiments,deficient （0 kg N· hm^-2） and excessive nitrogen supply （480 kg N· hm^-2） are disadvantaged to the yield and fiber quality.