Substitutive Effects of Upland Rice and Soybean Plant Populations on the Performance of the Component Crops in Intercropping System

A two–year field experiment was carried out in the 2018-2019 cropping seasons to determine the effect of substitutive plant population on the yield and productivity of component crops in the upland rice/soybean intercropping in the lowland humid region of Umudike, Southeast Nigeria. The treatments comprised three intercrop populations and one sole crop population of upland rice and soybean, which includes sole upland rice (Oryzae sativa L.) 100%, sole soybean 100%, Upland rice (Oryzae sativa L.) 25% + Soybean 75%, Upland rice (Oryzae sativa L.) 50% + Soybean 50% and Upland rice (Oryzae sativa L.) 75% + Soybean 25%. The experiment was laid out in randomized complete block design (RCBD) with three replications. The yield data collected were subjected to analysis of variance (ANOVA) using Genstat (2009), which includes grain yield of upland rice, number of panicles per plant, weight of seeds per panicle, weight of seeds per plant, and 1000-seed weight while soybean includes number of seeds per pod, number of seeds per plant, weight of seeds per plant. The treatments that received Rice 75/Soybean 25 produced the highest number of seeds/panicle weight of seeds/plant in 2018, while the correlation result showed a strong and positive association between grain yield of upland rice, number of panicle per plant, weight of seeds per panicle, weight of seeds per plant, and 1000-seed weight. Based on the result of the investigation, Rice 50/Soybean 50 gave the highest total land equivalent ratio (TLER), land equivalent ratio (LER), and % land saved in 2018. However, it was not consistent in 2019.