Cowpea and beet intercropping agro-economic dynamics under spatial arrangement and cowpea population density

ABSTRACT The objective of this work was to evaluate the effect of planting spatial arrangements between the cowpea and beet crops in intercropping and of cowpea population densities on the crop’s productivity and in the agro-economic efficiency of the association at two growing seasons. The experimental design was of randomised blocks with the treatments arranged in a 4 x 3 factorial scheme, in four replications. The first factor was constituted by three spatial arrangements between the component cultures (2:2, 3:3 and 4:4), formed by beet rows alternated with cowpea rows, while the second factor was constituted by the population densities of cowpea: 40, 60, 80 and 100% of the recommended population in single crop (RDSC). The production and its components were evaluated in the beet and cowpea. Apart from these characteristics, the following agro-economic indicators were also determined for each treatment: system productivity index (SPI), the land equivalent coefficient (LEC), and the monetary equivalent ratio (MER). The maximum production of commercial beet roots was obtained with 15.60 t ha-1 productivity at density of 61.82% of RDSC within the 4:4 arrangement, while the maximum yield of cowpea green grains of 2.23 t ha-1 was reached at density of 79.57% of RDSC within 2:2 spatial arrangement. The productivities of beet roots of extra A, extra AA and great types decreased with increasing cowpea population density, without any influence of the tested spatial arrangements. The maximum mean productivity of cowpea green pods of 1.74 t ha-1 was obtained at density of 87.47% of RDSC, reached within 2:2 spatial arrangement. The maximum economic efficiency of the cowpea-beet intercropping was obtained with MER of 1.11 at cowpea density of 100% of RDSC, irrespective of the spatial arrangement and growing season.

摘要 本研究旨在评估间作模式下豇豆与甜菜的种植空间配置，以及豇豆种植密度对两种作物产量及该联种体系农业经济效益的影响，试验在两个生长季开展。试验采用随机区组设计，处理组采用4×3因子设计，设置4次重复。第一因子为组分作物间的3种空间配置（2:2、3:3及4:4），即甜菜行与豇豆行交替种植；第二因子为豇豆种植密度，分别为单作推荐种植密度（Recommended Density in Single Crop, RDSC）的40%、60%、80%与100%。研究对甜菜与豇豆的产量及其构成要素进行了测定。除此以外，本研究还针对各处理组测定了以下农业经济指标：体系生产力指数（System Productivity Index, SPI）、土地当量系数（Land Equivalent Coefficient, LEC）以及货币当量比（Monetary Equivalent Ratio, MER）。在4:4空间配置下，当豇豆种植密度为单作推荐密度的61.82%时，商品甜菜块根最高产量达15.60 t·ha⁻¹；而在2:2空间配置下，当豇豆种植密度为单作推荐密度的79.57%时，豇豆鲜籽粒最高产量达2.23 t·ha⁻¹。特优级、特级及大规格甜菜块根的产量随豇豆种植密度升高而降低，且不受试验设置的空间配置影响。在2:2空间配置下，当豇豆种植密度为单作推荐密度的87.47%时，豇豆鲜豆荚平均最高产量达1.74 t·ha⁻¹。无论空间配置与生长季如何，当豇豆种植密度为单作推荐密度的100%时，豇豆-甜菜间作体系的最高经济效益对应货币当量比（MER）为1.11。