Growth and yield of soybean cultivated in agroforestry systems

ABSTRACT Agriculture has caused numerous concerns regarding the preservation of natural resources. In this context, agroforestry systems are emerging as a more sustainable alternative. The present study aimed to evaluate growth characteristics, radiation use efficiency, biomass partition, and yield of soybean grown in two agroforestry systems and full sun. A field experiment was conducted in Southern Brazil during the 2014/2015 crop year, in which transmissivity of solar radiation, leaf area index, radiation use efficiency, and yield of soybean were evaluated. The solar radiation dynamics varied among the study factors, mainly due to the agroforestry arrangements. Shading influenced the leaf area index, radiation use efficiency, biomass partition, and soybean yield. Based on the soybean yield values generated in this study, the use of more spaced agroforestry arrangements and Peltophorum dubium forest species is recommended. However, because the yield values were below the expected levels, it is not yet possible to confirm the full potential of soybean crop in agroforestry systems. Thus, new studies should be conducted in order to generate alternatives that make soybean cultivation feasible in agroforestry systems, such as assessing the use of more spaced agroforestry arrangements, the insertion of the soybean crop in the initial years of cultivation of agroforestry, as well as reduce intraspecific competition by decreasing the plant population of the crop.

摘要：农业活动在自然资源保护方面引发了诸多关切。在此背景下，农林业系统正逐渐成为更具可持续性的替代方案。本研究旨在评估两种农林业系统及全光照条件下种植的大豆的生长特性、辐射利用效率（radiation use efficiency）、生物量分配（biomass partition）与产量。本研究于2014/2015作物年度在巴西南部开展田间试验，对大豆的太阳辐射透射率、叶面积指数（leaf area index）、辐射利用效率及产量进行了测定。太阳辐射动态随试验因子的不同而存在差异，这主要由农林业配置模式所致。遮荫处理对大豆的叶面积指数、辐射利用效率、生物量分配及产量均产生显著影响。基于本研究获得的大豆产量数据，建议采用更宽间距的农林业配置模式，并搭配盾柱木（Peltophorum dubium）作为伴生树种。但由于本次试验的产量数据低于预期水平，目前尚无法确认大豆在农林业系统中的完整种植潜力。因此，亟需开展后续研究以探索可实现农林业系统大豆种植的可行方案，例如评估更宽间距农林业配置模式的应用效果、在农林业种植初期引入大豆种植，以及通过降低作物种植密度以缓解种内竞争（intraspecific competition）。