小麦秸秆还田和施钾对棉花产量与养分吸收的效应

在长江流域麦棉两熟制条件下,以Bt转基因抗虫棉为材料,设置不同秸秆还田量(4500 kg hm–2和9000 kg hm–2,即半量还田和全量还田)与施钾量(K2O,150 kg hm–2和300 kg hm–2)田间定位试验,研究小麦秸秆还田对棉花产量和主要养分吸收累积的影响及其与化肥钾的差异。结果表明,在施用氮磷肥的基础上,与对照相比,秸秆全量还田处理显著提高了铃数、铃重和皮棉产量,还田第2年和第3年产量增长率分别达143.5%和93.7%;显著提高了各生育时期尤其是吐絮期生物量和氮磷钾养分吸收量,延缓了棉花衰老。秸秆还田对钾吸收的促进效应大于氮磷,还田第3年棉株钾累积总量较对照增加335.1%,每生产100 kg皮棉钾吸收比例增大112.1%。秸秆全量还田处理(K2O,约折合150 kg hm–2)促进养分吸收、防止早衰及增产效应均显著大于秸秆半量还田处理,但显著低于施钾量(K2O)300 kg hm–2处理,与施钾量(K2O)150 kg hm–2处理的增产效果相当,但养分吸收量较150 kg K2O hm–2处理下降。

Effects of Wheat Straw Returning and K Fertilizer Application on Yield and Nutrients Uptake of Cotton

A three-year stationary experiment with treatments of wheat straw (4500 and 9000 kg ha^–1) mulching and K fertilizer (150 and 300 kg K₂O ha^–1) application was conducted using insect-resistant cotton under wheat-cotton double cropping system in the Lower Reaches of Yangtze River (Nanjing). The results showed that compared with control (without K fertilizer and wheat straw returning), total wheat straw returning significantly increased boll number, boll weight and lint yield of cotton with lint yield increasing rate of 143.5% and 93.7% in the second and third years after straw returning, respectively. Biomass and nutrients absorption at different growth stages were significantly improved by total wheat straw returning, especially in the boll opening stage, and the senescence of vegetative organs was delayed. Wheat straw returning promoted K absorption much greater than N and P absorption. Compared with control, total K uptake by cotton plant and K uptake per 100 kg lint increased by 335.1% and 112.1% respectively in the third year after straw returning. The treatment of total wheat straw returning much promoted nutrients uptake, yield, and delaying premature senescence than the treatment of half wheat straw returning, while significantly less than the treatment of 300 kg K₂O ha^–1. The yield-increasing effect was equal but the nutrients uptake per 100 kg lint was less in the treatment of total wheat straw returning than in the treatment of 150 kg K₂O ha^–1.