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为探讨减少盐碱地棉花铃脱落的途径,田间条件下研究了土壤供应低氮(N 226.5 kg.hm-2)和高氮(N 346.5 kg.hm-2)条件下,不打顶、打顶和打顶后涂抹生长素对棉花铃脱落和产量构成因素的影响。结果表明,低氮和高氮水平下,打顶、打顶后涂抹NAA处理果枝落铃率都低于不打顶处理。打顶后涂抹浓度为0.3 mmol.L-1的NAA处理在低氮水平下的成铃率比传统打顶处理高1.3个百分点,而铃脱落率比传统打顶处理低0.8个百分点,皮棉产量比传统打顶处理高23.7%。高氮水平下,与传统打顶处理相比,打顶后涂抹浓度为3 mmol.L-1的NAA单株成铃率、铃脱落率、皮棉产量之间差异不显著。在同一处理中,高氮水平的单株成铃数、单铃重和吐絮数均低于低氮水平,而衣分无明显差异,从而导致皮棉产量下降。上述结果说明,打顶后涂抹一定浓度的NAA可增加棉花单株现铃、成铃、吐絮数,增加单铃重,降低落铃率,从而提高产量,而过量施用氮肥会导致产量下降。
In order to explore the ways to reduce the boll loss of saline-alkali soil, under the conditions of low N supply (N 226.5 kg.hm-2) and high N (N 346.5 kg.hm-2) Effect of Topping with Auxin on Cotton Boll Fall and Yield Components. The results showed that under low nitrogen and high nitrogen levels, the boll loss rate of NAA was lower than that of untreated. The boll rate of NAA treated with 0.3 mmol.L-1 of topping was higher by 1.3 percentage points than that of the traditional topping treatment, while the boll loss rate was 0.8 percentage points lower than the traditional topping treatment. The lint yield 23.7% more than the traditional topping treatment. Compared with the traditional topping treatment, the boll rate, boll loss rate and lint yield of NAA plants with 3 mmol.L-1 application of topping were not significantly different at high nitrogen level. In the same treatment, the numbers of bolls per plant, boll weight and boll number per plant were all lower than those under low nitrogen level, but there was no obvious difference between the two treatments, which led to the decrease of lint yield. The above results show that applying a certain concentration of NAA after topping can increase the number of bolls, bolls and bolls per boll, increase single boll weight, and decrease the rate of falling boll so as to increase the yield. However, excessive application of nitrogen fertilizer will lead to the decrease of yield.