CORN-TREE PROXIMITY EFFECTS IN AGROFORESTRY EXPERIMENTS

ABSTRACT In agroforestry systems, annual plants closest to trees may behave differently from plants in rows that are more distant. This study evaluated the proximity effects of Mimosa caesalpiniifolia (sabiá) and Gliricidia sepium (gliricidia) on corn yield under the taungya and alley cropping systems. The two species were evaluated, in randomised blocks with five replications, in 2010 and 2011, under taungya and alley cropping, respectively. Three rows of corn (left, middle, and right) were grown between two rows of trees. Sabiá trees grew higher than gliricidia trees. The difference in crown diameter between species depended on plant age. There was a linear relationship between plant age and plant height and between plant age and crown diameter for both sabiá and gliricidia trees. In the taungya system, left rows produced more green ears than middle and right rows, but grain yield was higher in middle rows. In the alley system, green ear yield was also higher in left rows than in middle and right rows, but grain yield was unaffected by row position. In both agroforestry systems, there were no differences in corn yield for corn grown between sabiá or gliricidia trees.

摘要 在农林业系统（agroforestry systems）中，紧邻林木的一年生植物与间距更远的行内植株往往表现出不同的生长特性。本研究针对腾雅农作系统（taungya system）与带状间作农作系统（alley cropping system），评估了含羞草叶金合欢（Mimosa caesalpiniifolia，俗称sabiá）与Gliricidia sepium（俗称gliricidia）的邻近效应对玉米产量的影响。本研究分别于2010年与2011年，在腾雅农作系统与带状间作农作系统中，采用设置5次重复的随机区组设计对这两个树种进行了试验。试验设置两行林木，其间种植三行玉米（分别记为左行、中行与右行）。萨比亚合欢的树高高于Gliricidia sepium；两树种的冠幅差异随株龄变化而有所不同。对于萨比亚合欢与Gliricidia sepium而言，株龄与树高、株龄与冠幅均呈线性相关关系。在腾雅农作系统中，左行玉米的鲜穗产量高于中行与右行，但籽粒产量以中行最高；在带状间作农作系统中，左行玉米的鲜穗产量同样高于中行与右行，但籽粒产量不受行位影响。在两种农林业系统中，种植于萨比亚合欢与Gliricidia sepium林间的玉米产量均无显著差异。