黄土塬区玉米大豆不同间作方式对产量和经济收益的影响及其机制

利用不同玉米品种(郑单958和豫玉22)和大豆品种(中黄24和中黄13)在单作和两种(2∶2和2∶4)间作方式下,研究品种、间作方式对间作系统产量和经济效益的影响,探讨其潜在的作用过程和机制,以期为旱区农业高产高效服务。实验结果表明:(1)两种间作方式的土地当量比(LER),相对拥挤系数(K)都高于单作,表明玉米、大豆在两种间作方式下较单作具有显著的间作优势,玉米间作相比单作增产显著。K、实际产量损失(AYL)、侵占力(A)和竞争比率(CR)的变化规律均表明在间作栽培条件下,玉米相对于大豆为竞争优势物种;郑单958相对于豫玉22,中黄24相对于中黄13均占有一定竞争优势。郑单958与中黄24以2∶4比例间作的间作优势(IA)及货币优势指数(MAI)值最高。(2)相比单作,间作种植模式下玉米的水分利用效率明显增加,而且玉米∶大豆以2∶4间作的水分利用效率显著高于2∶2。郑单958与中黄24在2∶4间作方式下的产量和经济效益都最高,适合在当地应用和推广。

The effect and mechanism of intercropping pattern on yield and economic benefit on the Loess Plateau

One of the tasks of agricultural ecologist is to increase agricultural yield. How to improve agricultural practice is the biggest challenge in drought and barren environments on the Loess Plateau. Many studies have attempted to increase yield through the integration of plant population density, water and fertilizer use efficiency in this region. Intercropping, which is the simultaneous growing of two (or more) crop species in the same field, is a good solution to resolve this problem. Especially under low input conditions, the high yield attributes to resource complementarity in the intercropped system in which the component crops use the resources efficiently by dynamically balancing the different absorbing time, space-occupying or phenology. Maize (Zea mays L.) and soybean (Glycine max L.) are important crops in China selected as the inter-planted crops. A field experiment was conducted to investigate the yield and economic benefit in the intercrops of maize (Zhengdan 958 and Yuyu 22) with soybean (Zhonghuang 24 and Zhonghuang 13) in two planting patterns (2:2 and 2:4) respectively on the Loess Plateau, and the sole crops set as controls. Based on the interrelation between varied components and planting patterns as well as their relation to crop yield, competition indices, economic indices and water use efficiency under intercropped, we look forward to understanding potential regulation and mechanisms of maize/soybean intercropped system and serving for the agricultural production. The aboveground biomass, grain yield and water use efficiency were surveyed in each planting pattern. Several indices of competition and economic were calculated and used to evaluate the intercropped systems and analyze the competitive relationships between intercropped components. The results showed that the land equivalent ratio (LER) and relative crowding coefficient (K) were greater in maize-soybean intercropping than that in sole crop, indicating an advantage of intercropping. Yield of maize in maize-soybean intercropping was higher than that in single crop. The actual yield loss (AYL), aggressivity (A) and competitive ratio (CR) indicated that maize was the dominant species in maize/soybean intercropped system. Zhengdan 958 and Zhonghuang 24 showed more competitiveness on the water than the other two varieties in intercropping cultivation. The highest values of monetary advantage index (MAI) and intercropping advantage (IA) were recorded by the intercropping pattern of Zhengdan 958 and Zhonghuang 24 (with 2:4). The highest water use efficiency of maize was in intercropping pattern of 2:4, followed by intercropping pattern of 2:2, and sole crop was the lowest. As mentioned above, maize and soybean intercropped system had an obvious advantage in enhancing yield. The increases in biomass, yield and water use efficiency were caused by different varieties interaction and plant patterns significantly. Zhengdan 958 intercropped with soybean (Zhonghuang 24 and Zhonghuang 13) had advantage, indicating that Zhenggdan 958 is able to improve intercropping advantage. Zhengdan 958 and Zhonghuang 24 intercropped in patterns of 2:4 obtained the highest yield and water use efficiency among all treatments. Therefore, we suggest that Zhengdan 958 and Zhonghuang 24 intercropped in patterns of 2:4 had the highest economic benefit than the other patterns and thus may be adopted and popularized by farmers.