College of Agronomy, Sichuan Agricultural University, No. 211, Huimin Road, Wenjiang District, Chengdu, 611130, Sichuan, China.
Sichuan Engineering Research Center for Crop Strip Intercropping System, Southwest China, Key Laboratory of Crop Ecophysiology and Farming System in Southwest China, Sichuan Agricultural University, Chengdu, China.
Environ Sci Pollut Res Int. 2021 Aug;28(30):41135-41148. doi: 10.1007/s11356-021-13541-1. Epub 2021 Mar 29.
Maize/soybean relay intercropping system is a popular cultivation system to obtain high yields of both crops with reduced inputs. However, shading by maize decreases the photosynthetically active radiation, reaching the soybean canopy in maize/soybean relay intercropping system, which reduces soybean radiation use efficiency and competitiveness. Here, we reveal that compact maize in maize/soybean relay intercropping system enhances the photosynthetically active radiation transmittance, leaf area index, dry matter production, radiation use efficiency, and competitiveness of soybean and compensates the slight maize yield loss by substantially increasing soybean yield. In this experiment, soybean was relay intercropped with different maize types (SI, spreading maize; SII, semi-compact maize; and SIII, compact maize) in maize/soybean relay intercropping system, and all the relay intercropping treatments were compared with sole cropping systems of soybean and maize. Results revealed that SIII significantly enhanced the soybean radiation use efficiency (by 77%, from 0.35 g MJ in SI to 0.61 g MJ in SIII) and total radiation use efficiency (soybean radiation use efficiency + maize radiation use efficiency) of maize/soybean relay intercropping system (by 5%, from 3.53 g MJ in SI to 3.73 g MJ in SIII). Similarly, SIII improved the competitiveness (by 62%, from 0.58% in SI to 0.94% in SIII) of soybean but reduced the competitiveness (by 38%, from 1.73% in SI to 1.07% in SIII) of maize, which, in turn, considerably increased soybean yield by maintaining maize yield. On average, over the 2 years, in SIII, relay-intercropped soybean produced 89% of the sole soybean yield, and relay-intercropped maize produced 95% of the sole maize yield. Besides, treatment SIII achieved the mean highest land equivalent ratio value of 1.84 in both years. Thus, enhanced radiation use efficiency of soybean, especially during the co-growth period, was the primary factor responsible for the high productivity of the maize/soybean relay intercropping system.
玉米/大豆带状间作系统是一种获得高产、减少投入的流行种植系统。然而，玉米的遮荫会减少到达玉米/大豆带状间作系统大豆冠层的光合有效辐射，从而降低大豆的辐射利用效率和竞争力。在这里，我们揭示了在玉米/大豆带状间作系统中，紧凑型玉米增强了光合有效辐射透过率、叶面积指数、干物质生产、辐射利用效率和大豆的竞争力，并通过大幅提高大豆产量来弥补玉米产量的轻微损失。在这个实验中，大豆与不同类型的玉米（SI，展叶玉米；SII，半紧凑型玉米；SIII，紧凑型玉米）在玉米/大豆带状间作系统中进行了间作，所有间作处理都与大豆和玉米的单作系统进行了比较。结果表明，SIII 显著提高了玉米/大豆带状间作系统中大豆的辐射利用效率（从 SI 的 0.35 g MJ 提高到 SIII 的 0.61 g MJ，提高了 77%）和总辐射利用效率（大豆辐射利用效率+玉米辐射利用效率）（从 SI 的 3.53 g MJ 提高到 SIII 的 3.73 g MJ，提高了 5%）。同样，SIII 提高了大豆的竞争力（从 SI 的 0.58%提高到 SIII 的 0.94%，提高了 62%），但降低了玉米的竞争力（从 SI 的 1.73%降低到 SIII 的 1.07%，降低了 38%），这反过来又通过维持玉米产量而显著提高了大豆产量。平均而言，在 2 年中，SIII 中，间作大豆的产量达到单作大豆产量的 89%，间作玉米的产量达到单作玉米产量的 95%。此外，SIII 在这两年中的平均土地当量比最高，为 1.84。因此，大豆辐射利用效率的提高，特别是在共同生长期间，是玉米/大豆带状间作系统高生产力的主要因素。
