玉米株型和幅宽对套作大豆碳氮代谢及产量的影响

在玉/豆套作模式下，采用玉米株型与种植幅宽二因素裂区设计，研究了不同田间配置对套作大豆碳氮代谢与产量的影响。结果表明，较大幅宽和紧凑型玉米下，大豆被荫蔽的程度有所减缓，碳氮代谢变化趋势朝着利于产量形成的方向发展。主要表现为，茎叶中的碳氮含量和关健酶在各时期保持在较高的水平；R4期后叶片中的淀粉迅速降解为糖运至籽粒，而氮的下降速率缓慢。结合前期的研究，我们得出，R2是大豆经历光照转换的重要时期，该时期植株的碳氮代谢能力对大豆后期产量的形成起着重要的作用。而R6期大豆表现出来的碳、氮代谢水平，又能一定程度的反映产量水平。本试验条件下，对玉米、大豆两季作物的经济效益进行分析后得出，利于大豆生长，且保证全年高产，高效的最优组合为：与紧凑型玉米套作，大豆幅宽1.17m，玉米幅宽0.83m。

Effects of plant-types of maize and planting width on carbon-nitrogen metabolism and yield of relay-cropping soybean

Abstract: Field experiments were conducted to determine the optimal field combination that benefited soybean carbon-nitrogen metabolism and yield in “maize/ soybean” relay-cropping system. Split plot design was adopted, with different plant-types of maize as main plots, planting width as sub-plots. The results showed that under large width and relay cropping with erect maize, shade damage to soybean was reduced. The trend of soybean carbon-nitrogen metabolism was beneficial to high yield. The content of carbon and nitrogen and the activity of SPS and GS kept at a high level at every growing stage. After R4, the starch in leaf degraded into sugar quickly and transferred to grain, and the decreasing rate of nitrogen slowed down. Basis on our previous research work, the result suggested that R2 was the crucial stage for soybean to experience light change (maize harvest time was around R2), so the carbon-nitrogen metabolism ability of soybean at R2 had a strong impact for yield. And the carbon-nitrogen metabolism levels of soybean at R6 could partly reflect yield. In conclusion, relay-cropping soybean with erect maize in planting width 1.17m / 0.83m (soybean/maize) was the best field combination that could ensure high yield and efficiency all year round.