Beet-arugula intercropping under green manuring and planting density induce to agro-economic advantages

ABSTRACT One of the biggest challenges in the intercropping system of two crops is to obtain the optimal dose of green manure and the adequate population density of the crops. So, the objective of this work was to evaluate the performance of beet and arugula intercropping, influenced by green manuring with Merremia aegyptia and Calotropis procera and arugula population densities in two cultivation years, in semi-arid environment. The experimental design used was in randomized complete blocks, with the treatments arranged in a 4 x 4 factorial scheme, with 4 repetitions. The first factor of this scheme consisted of equitable amounts of M. aegyptia and C. procera biomass (20, 35, 50 and 65 t ha-1 on a dry basis) and the second factor, by arugula population densities (40, 60, 80 and 100% of the recommended density for single cropping, corresponding to 400, 600, 800 and 1,000 thousand arugula plants ha-1). The production and its components were evaluated on beet and arugula. In addition to these characteristics, the following agro-economic indicators were also determined for each treatment: system productivity index (SPI), land equivalent coefficient (LEC) and monetary equivalent ratio (MER). The greatest agro-economic advantages of the beet with arugula intercropping were achieved with a system productivity index (SPI) of 53.47 t ha-1, land equivalent coefficient (LEC) of 0.84 and a monetary equivalent ratio (MER) of 1.56, respectively, combining 65 t ha-1 of M. aegyptia and C. procera biomass with the arugula population density of 1,000 thousand plants ha-1. The maximum optimized commercial productivity of beetroots in the system intercropped with arugula was 23.20 t ha-1 using 65 t ha-1 of M. aegyptia and C. procera and in the arugula population density of 1,000 thousand plants ha-1, while the maximum arugula productivity intercropped with beet was 9.65 t ha-1, in the same combination of green manures amount and arugula population density.

摘要：双作物间作系统的核心挑战之一，在于确定最优绿肥施用量与适配的作物种群密度。本研究于半干旱环境下开展，涵盖两个种植季，旨在评估以银叶山猪菜（Merremia aegyptia）和牛角瓜（Calotropis procera）进行绿肥还田，以及芝麻菜种群密度对甜菜与芝麻菜间作表现的影响。本试验采用完全随机区组设计，处理设置为4×4因子组合，共4次重复。其中第一因子为等量的银叶山猪菜与牛角瓜生物量（以干重计分别为20、35、50和65 t·ha⁻¹），第二因子为芝麻菜种群密度（为单作推荐密度的40%、60%、80%和100%，对应每公顷40万、60万、80万及100万株芝麻菜）。本研究对甜菜与芝麻菜的产量及其构成因子进行了测定，除此以外还针对各处理计算了三类农业经济指标：系统生产力指数（System Productivity Index, SPI）、土地当量系数（Land Equivalent Coefficient, LEC）及货币当量比（Monetary Equivalent Ratio, MER）。结果表明，当银叶山猪菜与牛角瓜生物量施用量为65 t·ha⁻¹，且芝麻菜种群密度为100万株·ha⁻¹时，甜菜与芝麻菜间作的农业经济优势最为显著，此时系统生产力指数（SPI）达53.47 t·ha⁻¹，土地当量系数（LEC）为0.84，货币当量比（MER）为1.56。在该绿肥施用量与芝麻菜种群密度组合下，间作系统中甜菜根的最优商品产量为23.20 t·ha⁻¹，而间作芝麻菜的最高产量可达9.65 t·ha⁻¹。