不同水氮处理对玉米-大豆间作群体内作物光能截获、竞争和利用的影响

通过田间试验研究了不同水氮处理对玉米-大豆间作群体的光能截获、竞争与利用的影响。试验设置充分供水和水分亏缺两种水分处理以及施氮(亩施纯氮7.5 kg)和不施氮两种氮肥处理。结果表明,在生育中后期,同一氮肥处理条件下,充分供水处理间作作物的光能截获率显著高于水分亏缺处理;相同水分条件下,施氮处理间作大豆的光能截获率略高于不施氮处理,但未达到显著水平,而施氮处理间作玉米的光能截获率则显著高于不施氮处理。从播后第64天到成熟,同一氮肥处理条件下,充分供水提高了间作玉米的光能竞争比,但却降低了间作大豆的光能竞争比。从播后第73天到成熟,相同水分条件下,施氮处理间作玉米的光能竞争比显著高于不施氮处理,而大豆的光能竞争比在两个氮肥处理间则没有显著差异。充分供水条件下,施氮处理间作玉米的光能利用效率(LUE)为3.87 g/MJ,略高于不施氮处理(3.81 g/MJ);水分亏缺条件下,施氮处理间作玉米的LUE(3.86 g/MJ)比不施氮处理(3.72 g/MJ)高3.6%。充分供水条件下,施氮处理间作大豆的LUE(1.62 g/MJ)比不施氮处理(1.57 g/MJ)高3.2%;水分亏缺条件下,施氮处理间作大豆的LUE为1.55 g/MJ,与不施氮处理(1.54 g/MJ)基本相同,表明与氮肥处理相比,水分状况对大豆LUE的影响更为明显。

Effects of water and nitrogen on interception, competition and utilization of radiation in a maize-soybean intercropping system

The growing population is driving global demand for increased agricultural production while arable land is being lost with urbanization and degradation. Intercropping is often a reliable way of using land and other resources more effectively. Maize-soybean intercropping may raise land productivity by improving the use efficiency of water, nutrient, and radiation resources. Water and fertilizer conditions have obvious influences on canopy growth and development, thus affect radiation capture and utilization. However, few experiments were carried out to investigate effects of different water and nutrients combinations on radiation capture, competition and utilization in intercropping system. Therefore, an experiment was carried out to investigate effects of different water and nitrogen levels on radiation interception, competition and utilization in a maize-soybean strip intercropping system. The intercropping system consisted of two rows of maize and three rows of soybean flanked each other. The experiment design was consisted of 2 water levels, as sufficient water supply (soil moisture low limit was set as 75% of the field capacity) and water deficit (soil moisture low limit was set as 60% of the field capacity), and 2 nitrogen levels, as nitrogen application of 7.5 kg N per 667 m² and no nitrogen application. The total number of treatments was 4 and 3 replications were arranged. Experimental results indicated that under same nitrogen application level, the fraction of radiation intercepted by the intercropped crops on sufficient water supply plots was higher than those on water deficit plots during the medium-late stage. Under same water level, the fraction of radiation interception of the intercropped soybean on nitrogen application plots was slightly greater than that on no nitrogen application plots, but the difference was not significant. However, the radiation interception fraction of the intercropped maize on nitrogen application plots was significantly greater than that on the no nitrogen plots. For the treatments with same nitrogen application, the radiation competition ratio of the intercropped maize increased and the radiation competition ratio of the intercropped soybean decreased as the water supply was improved during the period of 64 days after sowing to maturity. Under same water application level, the radiation competition ratio of the intercropped maize on nitrogen application plots was significantly greater than that on no nitrogen plots during the period of 73 days after sowing to maturity, while it was not significant that the difference between the radiation competition ratios of the intercropped soybean on the two nitrogen treatments. For sufficient water supply treatments, light use efficiency (LUE) of the intercropped maize was 3.87 g/MJ on nitrogen application plots, and slightly higher than that (3.81 g/MJ) on no nitrogen application plots. However, for water deficit treatments, LUE of the intercropped maize was 3.86 g/MJ on nitrogen application plots and 3.72 g/MJ on no nitrogen application plots, an increasing of 3.6%. Under sufficient water supply, LUE of the intercropped soybean on nitrogen application plots (1.62 g/MJ) was higher than that on no nitrogen application plots (1.57 g/MJ) by 3.2%, while, a LUE of 1.55 g/MJ for the intercropped soybean on nitrogen application plots was nearly same to a LUE of 1.54 g/MJ on no nitrogen application plots under water deficit. It can be deduced that the influence of water condition on LUE of intercropped soybean was more significant than that of nitrogen condition.