Row and Plant Spacing Effects on Yield and Yield Components of Soya Bean Varieties Under Hot Humid Tropical Environment of Ethiopia

Abstract

Appropriate plant density is a key for gainful production of soya bean in various environments including the hot-humid tropical environments (HHTE) of Ethiopia. A split-plot factorial experiment was conducted under HHTE in south-west Ethiopia to determine the effect of Variety (Clark, CSC-1), Row spacing (50, 55, 60, 65, 70 cm) and Plant spacing (2.5, 5, 10 cm) on yield and yield components, and weed infestation of soya bean. The effect of Plant spacing was more Variety-specific than that of Row spacing. Yield and yield components per m2 were significantly affected by both Row spacing and Plant spacing. However, per plant and per pod responses and weed infestation were affected mainly by Plant spacing, and not that much by Row spacing. Seed yield and yield components per m2 were the highest for the highest plant density (50 cm Row spacing, 2.5 cm Plant spacing), but individual plant and pod responses, and weed infestation were the highest for wider Plant spacing (10 cm). Regression analysis of various responses on planting density showed negative, cubic relationship albeit with different strength. This study demonstrated that these factors significantly modify soya bean yield and yield components as well as weed infestation, suggesting that they could be used as management tools for increased yield in HHTE.