Effect of replacement intercropping ratios of sweet corn with bean varieties on yield and yield components

Introduction Conservation agriculture (CA) has been proposed as a set of principles that could help reverse widespread soil degradation in the region and help farmers stabilize yields by mitigating the effects climate variability. Though numerous questions remain on how CA practices might fit in a complex mix grain- grazing farming systems, where limited land, cash and labor impose severe constraints on farmers’ options. Intercropping is a CA approach that has been traditionally practiced in many parts of world and has some advantages over monocultures. One of its obvious advantages may be to increase forage protein, the principle being improvement of forage quality through the complementary effects of two or more crops grown simultaneously on the same area of land. Intercropping supplies efficient resource utilization, reduces risk to the environment and production costs, and provides greater financial stability, making the system more suitable particularly for labor-intensive, small farmers. Morpho-physiological differences and agronomic factors such as the proportion of crops in the mixture and fertilizer application regulate competition between component crops for growth-limiting factors. Greater total uptake of nutrients and other growth factors by the component crops in the intercropping is the primary cause of obtaining intercropping advantage. Intercropping research studies involving a cereal and a legume have not considered the combined effect of fertilizer application and plant population variation. Maize and beans are important food crops, mostly grown by resource- poor farmers in complex and risky farming systems. Morgado & Willey (2003) showed that competitive effect of intercrop beans on maize yields was high at higher plant populations. Materials & Methods In order to study the production potential and competitiveness of sweet corn and bean varieties, an experiment was carried out based on a randomized complete block design with three replications in the Agricultural Research Station, Ferdowsi University of Mashhad, during growing season of 2014-2015. Treatments included different combinations of bean (B) and sweet corn (C): 25%B+75%C, 50%B+50%C, 75%B+25%C and bean varieties and their monoculture. Bean varieties consisted cowpea, white, red, pinto and landrace and chase sweet corn. Studied criteria were yield components (pod number per plant, seed number per pod and 100-seed weight), biological yield, seed yield and harvest index (HI) of bean and biological yield, seed yield and HI of sweet corn and land equivalent ratio (LER). Results & Discussion The results indicated that effect of intercropping ratios were significant (p≤0.05) on seed yield, biological yield, HI, pod number per plant and seed number per pod and biological yield and seed yield of bean. The highest seed yield of bean was observed in 75%B + 25%C with 1675 g.m-2 and the lowest was related to 25%B + 75%C with 778 g.m-2. The maximum seed yield was obtained in pinto (2342.33 g.m-2) and the minimum was achieved in landrace (847.75 g.m-2). Seed yield of sweet corn in monoculture was higher than intercropping ratios, but by increasing density in intercropping ratios with bean varieties it significantly enhanced. The highest and the lowest seed yield in intercropping ratios were observed in 75%C + 25%B with 7348.1 g.m-2 and 25%C + 75%B with 3466 g.m-2, respectively. In all combinations of intercropping ratios LER was higher than 1, that it represents intercropping is better than monoculture. The maximum land equivalent ratio was calculated with 1.47 for 25%B (landrace) + 75%C. The results showed that landrace was competitive than other varieties. Conclusion The effect of intercropping ratios of sweet corn with bean landraces were significant (p≤0.05) on seed yield, biological yield, HI and yield components of the crops. The maximum seed yield was obtained in pinto and the minimum was achieved in landrace. Seed yield of sweet corn in monoculture was higher than intercropping ratios, but by increasing density in intercropping ratios with bean varieties it significantly enhanced. According to the results, intercropping of plants of 25%B (landrace) + 75%C can be beneficial in term of ecological management.