氮肥对非充分灌溉下棉花产量及品质的补偿作用

【目的】水分不能按照棉花正常需水量进行灌溉，对棉花生长发育、产量及品质会造成一定影响，本文旨在通过研究氮肥施用量来缩小因灌溉水不足对棉花所造成的影响，以期为干旱地区棉花水肥高效利用提供理论依据。【方法】试验以棉花‘新陆中54号’为材料，采用裂区试验设计，主区为总灌溉量，分别为2800 m3/hm2 (非充分灌溉)、3800 m3/hm2 (常规灌溉)，副区为4个施氮 (N) 水平，即0 kg/hm2 (N0)、150 kg/hm2 (N150)、300 kg/hm2 (N300)、450 kg/hm2 (N450)。测定了棉花的生长、棉绒品质和棉花的肥水利用率。【结果】同一氮肥处理下，非充分灌溉处理干物质与氮素最大积累速率出现时间及拐点时间均较常规灌溉处理提前，干物质与氮素最大积累量及积累速率、干物质与氮素向生殖器官分配比例、氮素向生殖器官的转移率、籽棉产量及品质均低于常规灌溉处理，但籽棉增产率、氮肥农学利用率及水、氮利用率均高于常规灌溉处理。同一灌溉量下，随着施氮量的增加，干物质与氮素最大积累速率出现时间、拐点时间表现为N450 > N300 > N150 > N0，干物质与氮素积累量及积累速率、最大生长特征值、干物质与氮素向生殖器官分配比例及转移率、籽棉产量及品质、水分利用率均表现为N300 > N450 > N150 > N0，籽棉增产率、氮肥农学利用效率及氮肥利用率表现为N300 > N450 > N150。非充分灌溉下增施氮肥的补偿效果随着氮肥用量的增加呈先增加后下降的趋势，N300处理补偿效果最为显著，与常规灌溉处理相比，补偿效应主要表现在干物质与氮素最大积累速率提高了1.9%、3.1%，干物质向生殖积累器官分配比例及氮素转移率提高了24.0%、5.1%，水、氮利用率提高了6.1%～8.8%、17.3%～17.9%，籽棉增产率提高了6.1%～8.8%，纤维长度、整齐度及比强度提高了4.3%～20.1%、5.7%～7.3%及2.2%～12.5%。氮肥对棉花生长发育的影响大于水分。【结论】非充分灌溉下，施N 300 kg/hm2棉花可正常生长，干物质与氮素积累量适宜，向生殖器官分配比例及转移率较高，水、氮利用率最高，且节水26.3%。棉花虽然在产量与品质上有所下降，籽棉产量较常规灌溉几乎没有下降。从干旱地区农业缺水的现实考虑，在南疆采用非充分灌溉下，施氮300 kg/hm2可补偿缺水对棉花产量和品质的影响。

Compensation effects of nitrogen fertilizer on yield and quality of cotton under insufficient irrigation

【Objectives】Insufficient irrigation might cause adverse effect on cotton growth, yield and quality. This paper studied the suitable nitrogen fertilizer rate to alleviate the adverse impact of insufficient irrigation.【Methods】Using cotton cultivar of ‘Xin Lu Zhong No.54’ as tested material, a split plot experiment was conducted. The main factor was total irrigation amount of 2800 m3/hm2 (insufficient irrigation) and 3800 m3/hm2 (sufficient irrigation); the deputy area was nitrogen levels of 0, 150, 300 and 450 kg/hm2. The cotton growth and lint quality were determined, and water use efficiency was calculated at harvest stage.【Results】Under the same treatment levels of nitrogen, the maximum accumulation rate of dry matter and nitrogen and the inflexion point in insufficient irrigation arrived earlier than those in conventional irrigation; the dry matter and nitrogen accumulation amount and the maximum accumulation rate, the allocation ratio of dry matter and nitrogen in reproductive organ, the transfer efficiency of nitrogen to reproductive organ, the seed cotton yield and quality were lower; but the seed cotton yield increase rate, the nitrogen agronomic use efficiency, the water and nitrogen use efficiency were higher. Under both the irrigation treatments, with the increase of nitrogen fertilizer rate, the maximum accumulation rate and the inflexion point of dry matter and nitrogen arrived the earliest in N450, followed by N300, N150, N0 in turn; the dry matter and maximum N accumulation amount and accumulation rate, the maximum growth characteristic value, the allocation ratio of dry matter and nitrogen to the reproductive organ, the transfer efficiency of nitrogen to reproductive organ, the seed cotton yield and quality and water use efficiency were in order of N300 > N450 > N150 > N0; the seed cotton yield increase rate, the nitrogen agronomic use efficiency and nitrogen use efficiency were in order of N300 > N450 > N150. The compensation effect of N fertilizer showed the trend of firstly increase and then decrease with the increase of the nitrogen rate under insufficient irrigation, the compensation effect of N300 treatment was the most significant. Compared with sufficient irrigation treatment, the compensation effect mainly showed that the maximum accumulation rates of dry matter and nitrogen were increased by 1.9% and 3.1%, the allocation ratio of dry matter to the reproductive organ and the transfer efficiency of nitrogen to reproductive organ were raised by 24.0% and 5.1%, water and nitrogen use efficiencies were enhanced by 6.1%–8.8% and 17.3%–17.9%, the seed cotton yield increase rate was increased by 6.1%–8.8%, the fiber length, the fiber uniformity and fiber strength were increased by 4.3%–20.1% and 5.7%–7.3% and 2.2%–12.5%, respectively. The effect of nitrogen fertilizer on cotton growth was greater than that of water.【Conclusions】At N rate of 300 kg/hm2, there is no significance difference in the cotton yield and fiber quality between the insufficient irrigation and sufficient irrigation. With this N rate under insufficient irrigation condition, cotton plants can keep normal growth, the dry matter and N accumulation are suitable, and their distribution rates are high, so the water and nitrogen use efficiencies are high. Considering the water shortage in the south of Xinjiang, applying nitrogen of 300 kg/hm2 could compensate the adverse impact of insufficient irrigation and increase cotton fiber quality, water and nitrogen use efficiency is the highest, and cotton fiber quality is increased, water and nitrogen use efficiency is the highest, and water saving is 26.3%.