Cowpea [Vigna unguiculata (L.) Walp.] cultivars with high yield potential and suitable plant architecture for mechanized harvesting have recently shown a growing interest to be cultivated as a second crop in fall–winter season of southeastern Brazil. The agronomic optimal plant density (AOPD) is one of the main management factors defining attainable yield. However, in the scientific literature for semiupright cowpea cultivars grown in fall–winter season in southeastern Brazil the AOPD is not yet clearly defined. A 3‐yr study was conducted to evaluate the effect of five plant densities (100,000–500,000 plants ha⁻¹) on growth, seed yield and its components for two cowpea cultivars (BRS Guariba and BRS Novaera) in Botucatu, southeastern Brazil. The AOPD for cowpea increased as the attainable yield improved. The increase in plant density promoted increases in leaf area index (LAI) and the position (measured in height) of the first pod insertion for cowpea plants, but negatively affected per‐plant scale surviving rate, leaf area, aboveground dry matter (DM), and yield resulting from intraspecific competition. Maximum cowpea seed yields were achieved with AOPD ranging from 216,630 to 290,537 plants ha⁻¹ (8–24% greater than under the lowest plant density). On average, 259,000 plants ha⁻¹ was estimated for the AOPD to achieve maximum seed yield of semiupright cowpea grown as a second crop in fall–winter season in southeastern Brazil.

中文翻译：

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巴西东南部半立式cow豆作为第二作物的农艺最佳植物密度

Brazil豆（Vigna unguiculata（L.）Walp。）具有高产量潜力和适合机械化收割的适宜植物结构的栽培品种最近显示出在巴西东南部秋冬第二季种植第二作物的兴趣。农艺最佳植物密度（AOPD）是定义可达到的产量的主要管理因素之一。但是，在巴西东南部秋冬季生长的半立式cow豆品种的科学文献中，尚未明确定义AOPD。进行了为期3年的研究，以评估五种植物密度（100,000–500,000公顷ha ^-1）关于巴西东南部博图卡图的两个cow豆品种（BRS Guariba和BRS Novaera）的生长，种子产量及其组成。随着可达到的产量提高，cow豆的AOPD增加。植物密度的增加促进了cow豆植物的叶面积指数（LAI）和第一个荚果插入位置的增加（高度测量），但对每株规模的成活率，叶面积，地上干物质（DM）产生了负面影响，以及种内竞争产生的产量。使用AOPD可获得最大的cow豆种子产量，范围为216,630至290,537公顷ha ^-1（比最低植物密度高8-24％）。平均259,000株公顷^-1 据估计，在巴西东南部的秋冬季，作为第二种作物的半立式cow豆的AOPD可以达到最大的种子产量。