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 在农林业系统中，紧邻树木的一年生作物与距离树木较远的行内作物可能表现出不同的生长特性。本研究针对梯园农作（taungya）与条带间作（alley cropping）两种农林业系统，评估了Mimosa caesalpiniifolia（sabiá）与Gliricidia sepium（gliricidia）的邻接效应对玉米产量的影响。本研究于2010年与2011年分别针对梯园农作与条带间作系统，设置5次重复的随机区组试验，对这两个树种进行评估。试验设置两行树木之间种植三行玉米（分别为左侧行、中间行与右侧行）。Sabiá树的株高高于gliricidia树。两个树种的冠幅直径差异取决于植株树龄。对于sabiá与gliricidia两种树种而言，植株树龄与株高、树龄与冠幅直径均存在线性相关关系。在梯园农作系统中，左侧行的玉米鲜穗产量高于中间行与右侧行，但中间行的玉米籽粒产量更高。在条带间作系统中，左侧行的玉米鲜穗产量同样高于中间行与右侧行，但籽粒产量不受行位的影响。在两种农林业系统中，种植于sabiá树与gliricidia树之间的玉米产量均无显著差异。