不同覆盖类型下减量施肥对油菜产量及水肥利用效率影响

为了探讨覆盖与缓释肥(节水节肥)技术对西南旱地油菜生长及水肥利用效率的影响,设置了由3种栽培模式(传统平作栽培、秸秆覆盖和沟垄集雨节水栽培)和3种施肥模式(习惯施肥、减施缓释肥、不施肥)组成的双因素大田定位试验,比较分析2a不同降水年型下覆盖与缓释肥技术对油菜生长的调控效应。结果表明,2016-2017年苗期降水异常偏多,2017-2018年偏少。苗期降水异常偏多对油菜生长的影响大于季节性干旱,2017-2018年苗期根冠比2016-2017平均增加83.55%。多雨年型(2016-2017)下产量及其构成值均低于季节性干旱年型(2017-2018)。单一的节水技术在季节性干旱发生时无显著的增产效应。季节性干旱和降水异常偏多均会影响油菜品质,且多雨会进一步降低了含油量及某些脂肪酸含量;干旱对脂肪酸构成影响更大。2 a节水节肥处理总耗水量均较习惯栽培加传统施肥显著减少,节水节肥处理水分利用效率较习惯栽培加传统施肥高8%～40%,并显著增加肥料利用效率。综上,单一的节水或节肥技术难以满足西南旱地油菜生产面临的复杂环境,通过秸秆覆盖和沟垄集雨与缓释肥集成的双节技术,能适宜不同降水年型下的油菜生产并兼顾环境效应,缓解生育期降水异常对作物生长的影响,实现节本增效的目标。

Effects of reducing fertilizer application rate under different mulching types on yield and water-fertilizer utilization efficiency of rapeseed

In order to investigate the effects of different cultivation technologies on the yield, water and fertilizer utilization efficiency of rapeseed (Brassica napus L.), a 2-factor complete random design experiment was conducted, which included 3 cultivation models (flat cultivation, straw mulching and ridge-furrow rainfall harvesting) and 3 fertilization models (conventional fertilization rate and type, reducing application rate with slow-release fertilizer and no fertilizer). The experiment was carried out in Baoping town of Yunyang county, Chongqing, China. The rapeseed variety was Sanxiayou No.5. The conventional fertilizer was urea (N 46%). The application rate of the conventional fertilizer was 225 kg/hm2 N, 63 kg/hm2 P and 72 kg/hm2 K. The application rate of the slow release fertilizer was 180 kg/hm2 N, 50 kg/hm2 P and 58 kg/hm2 K. In the slow release fertilizer, the N, P and K content were 25%, 7% and 8%, respectively. The experimental plot was 4 m in width and 4 m in length. During the experiments, the precipitation was measured. The plant height, dry matter and root shoot ratio were determined. After harvesting, the pod number, seeds number per plant, 1 000 grain weight and yield were determined too. Protein, oil content and fatty acid were measured. The water consumption and water use efficiency were calculated. The apparent utilization efficiency, agronomic efficiency and physiological efficiency of N, P and K were calculated. The results showed that it was rainy in 2016-2017 and had seasonal drought during the nutritional growth stage in 2017-2018. The yield and its composition values were lower in rainy year than in seasonal dry year. The single water-saving technology had no significant effect on yield increase when seasonal drought occurred. The water-saving and fertilizer saving technology could not only stabilize the yield when there was a lot of rain, but also obtained enough water during drought to increase the yield. The technique of straw mulching plus reducing application rate of slow-release fertilizer and furrow ridge rainwater collection plus reducing application rate of slow-release fertilizer could improve stress resistance at seedling stage of rapeseed, increased the effective pod number per plant and thus improved the yield and maintained the stability of the quality of rapeseed. At the same time, compared with the conventional cultivation under 2 different precipitation conditions, the technique of straw mulching plus reducing application rate of slow-release fertilizer and furrow ridge rainwater collection plus reducing application rate of slow-release fertilizer could reduce the water consumption of rapeseed, increase the water use efficiency by 8%-40%, and increased the fertilizer use efficiency. Considering results of this study and ecological condition in arid field of southwest, we suggested the technique of straw mulching plus reducing application rate of slow-release fertilizer and furrow ridge rainwater collection plus reducing application rate of slow-release fertilizer. The slow-release fertilizer was applied once as base with the application rate of 720 kg/hm2. The technique combined with others such as hole broadcast could effectively relieve the adverse impacts of abnormal climate conditions on the growth and yield of rapeseed to achieve high yield and quality.