施氮量对棉铃干物质和氮累积及分配的影响

以高品质棉（科棉1号）和常规棉（美棉33B）品种为材料，2005年在江苏徐州（11711E, 3415N）、2007年在河南安阳（11413E, 3604N）设置施氮量（低氮N 0 kg/hm2，适氮N 240 kg/hm2，高氮N 480 kg/hm2）试验，研究施氮量对棉铃干物质、氮累积分配和棉铃（纤维、棉子）品质的影响。结果表明:施氮可改变棉铃各部分干物质和氮素的累积特征，进而影响棉铃重和棉铃品质。在本试验N 240 kg/hm2水平下，单铃棉子和纤维的干物质累积量最大，棉铃各部分（铃壳、纤维、棉子）氮含量适中、氮累积量最高，最终铃重最大，棉纤维和棉子品质最优；在不施氮（N 0 kg/hm2）时，棉铃干物质和氮快速累积期开始较早、累积速率较低，最终干物质和氮累积量均较低，铃重最低，棉纤维和棉子品质最差。在N 480 kg/hm2水平下，棉铃各部分（铃壳、纤维、棉子）的氮含量和累积量提高，且在成熟棉铃中棉纤维干物质的分配系数下降，棉子中的氮分配系数提高，最终棉子中蛋白质含量上升，铃重和棉纤维比强度、棉子油分含量均降低。综上所述，施氮量过低影响棉铃干物质和氮素的累积，而施氮量过高则主要影响棉铃干物质和氮素在铃壳、棉子和纤维间的分配，二者均导致最终的铃重降低、棉纤维和棉子品质变劣。

Effects of nitrogen fertilization on accumulation and distribution of dry weight and nitrogen of cotton bolls

To investigate the responses of the accumulation and distribution of dry weight and nitrogen of cotton bolls to nitrogen applications and their relationships with fiber and seed quality characteristics, field experiments were carried out in Xuzhou (11711E, 3415N) and Anyang (11413E, 3604N) using two cotton cultivars, Kemian 1 and NuCOTN, with three nitrogen levels (N0, 240 and 480 kg/ ha). The results show that the dry weights, nitrogen accumulation characteristics of cotton bolls (shell, fiber and seed) and quality of cotton bolls are affected under the N fertilization. In a single boll, at the N240 kg/ha, its dry weight is the highest except cotton shell, its nitrogen content is in the middle, and its nitrogen accumulation amount is the highest. Thus the boll weight is the highest and the cotton boll quality (fiber and cottonseed quality) is the best. At the N 0 kg/ ha, the start time of rapid dry weight is earlier, the rates of dry weight and nitrogen accumulation are slower, and the dry weight and nitrogen accumulation amounts are lower, which result in the lowest boll weight and the poorest cotton boll quality. At the N 480 kg/ha, the nitrogen content and accumulation amount are increased in cotton bolls. In mature one, dry weight distributive indices are decreased in cotton fiber, while nitrogen distributive indices are increased in cotton seeds. The seed protein content is increased, while boll weight, fiber strength and seed oil content are decreased. These results indicate that the low nitrogen rate affects the transportation of photosynthesis production and nitrogen to bolls, the high nitrogen rate affects the distribution of cotton dry weight and nitrogen in cotton bolls, and both of the rates decrease the boll weight and qualities of fiber and cotton seeds.