GROWTH AND YIELD PERFORMANCE OF COMMON BEAN ( PHASEOLUS VULGARIS   L.) AS INFLUENCED BY PLANT DENSITY AT NYAGATARE, EAST RWANDA

Common bean (Phaseolus vulgaris L.) is one of the most important priority crops grown in Rwanda. It is utilized as a staple food and is consumed as edible seeds and pods for provision of proteins. Best agronomic practices that would promote its optimum growth and maximum yield should be recommended. Plant density affects productivity of common bean and optimizing it would increase light interception by the crop and minimize competition between plants, resulting into improved crop growth rate and yield. To determine the effect of plant density on common bean growth and yield, four different plant densities: 200,000, 250,000, 300,000, 350,000 plants/ha were investigated in a randomized complete block design, with three replications. Interaction effects between plant density with these parameters: plant height, plant biomass, number of pod per plant, 100grain weight and yield were assessed using analysis of variance (ANOVA). Results indicated that plant height was significantly affected by bean planting density (P<0.001), and was significantly higher in 350,000 plants ha^-1 than for all other plant densities. Bean biomass was significantly affected by plant density (p=0.007) and was significantly higher in 250,000 plants ha^-1. Bean planting density significantly affected the number of pods plant^-1(P<0.001) and total bean yield (P<0.001). The number of pods plant^-1 was highest at 249.5% using 200,000 plants ha-1while 350,000 plants ha^-1 density produced the lowest number of pods plant^-1. Bean yield was significantly higher in 250,000 plants ha^-1 and lowest in 350,000 plants ha^-1. Hundred (100) grains weight was significantly affected by plant density (p<0.001). The highest 100grains weight was found in 200,000 plant ha^-1 while the lowest was found in 350,000 plants ha^-1. These results indicate that 250,000 plants ha^-1 population favors higher bean growth and grain yield. This study will provide an important basis to establish appropriate planting densities recommended for the bean crop in different agro-ecological zones of Rwanda.

Keywords
Common bean; plant density; plant growth; field performance; biomass; yield