玉米–大豆带状套作行距配置对作物生物量、根系形态及产量的影响

空间配置是影响间作套种作物生长和产量构成的关键因素之一。本研究固定玉米–大豆套作带宽200 cm,玉米采用宽窄行种植,设置4个玉米窄行行距为20 cm(A1)、40 cm(A2)、60 cm(A3)和80 cm(A4)套作处理,2个玉米和大豆净作对照处理,研究行距配置对套作系统中玉米和大豆生物量、根系及产量的影响。结果表明,套作大豆冠层光合有效辐射和红光/远红光比值均低于净作,且随着玉米窄行的增加而降低。套作系统中大豆地上地下生物量、总根长、根表面积和根体积从第三节龄期(V3)到盛花期(R2)逐渐增加,但随着玉米窄行的增加而降低。套作玉米地上地下生物量从抽雄期到成熟期逐渐增加,根体积却逐渐降低,但这些参数随玉米窄行的变宽而增加。玉米和大豆在带状套作系统中产量均低于净作,且随玉米窄行的变宽,玉米产量逐渐增加,2012和2013两年最大值平均为6181 kg hm–2,而大豆产量逐渐降低,两年最大值平均为1434 kg hm–2,产量变化与有效株数和粒数变化密切相关。此外,玉米–大豆带状套作群体土地当量比(LER)大于1.3,最大值出现在A2处理,分别为1.59(2012年)和1.61(2013年),且最大经济收益也出现在A2处理(2年每公顷平均收益为1.93万元)。因此,合理的行距配置对玉米–大豆带状套作系统中作物的生长、产量构成和群体效益具有重要的作用。

Effects of Row Spacing on Crop Biomass,Root Morphology and Yield in Maize-Soybean Relay Strip Intercropping System

Spatial patterns of cropping directly affect crop growth and yields in intercropping systems. A two year field experiment was conducted in 2012?2013 to analyze the effects of different row spacing patterns in maize and soybean relay strip intercropping system at 2:2 maize-to-soybean on crop biomass, root morphology and yield. The treatments were six row spacing patterns including four maize planting patterns with the control of sole cropping of maize and soybean. The maize planting patterns were compound of wide row and narrow row lying: “180+20” cm, “160+40” cm, “140+60” cm, and “120+80” cm. Soybean was planted in the wide rows before the reproductive stage of maize. The row spacing of the sole cropping of maize and soybean was 70 cm. The biomass, total root length, root surface area and root volume of intercropped soybean increased from V3 to R2, and decreased with increasing the maize narrow-row spacing. The above- and below-ground biomass of intercropped maize increased from tasseling to maturity stages, whereas opposite results were found in root volume. In addition, the intercropped maize biomass and root volume increased with increasing maize narrow-row spacing. The yields of maize and soybean in intercropping condition were lower than those in monoculture. Yield of intercropped maize increased with increasing the maize narrow-row spacing, with an average of two year maximum values of 6181 kg ha^-1. Contrary trends were observed in intercropped soybean, with an average maximum yield of 1434 kg ha^-1. Crop grain yield was related to effective plants and grain numbers per plant in maize-soybean relay strip intercropping system. Total intercropping yields were higher than sole cropping yields of maize and soybean, and the land equivalent ratio (LER) of the intercropping system was above 1.3. The maximum LER appeared in “60+40” cm treatment, which was 1.59 and 1.61 in 2012 and 2013, respectively. Similar results were found in economic benefit, the average of maximum value in both years was 19.3 thousand Yuan per hectare. Therefore, optimum row spacing pattern plays an important role in improving crop growth and increasing yield in maize-soybean relay strip intercropping system.