Effect of plant density on growth and yield attributes of common bean (Phaseolus vulgaris L.) genotypes

Common bean (Phaseolus vulgaris L.) is an economically significant seed crop in tropical regions. With the objective of studying the effect of plant density on growth and yield characteristics of common bean, four common bean varieties (‘GLP190S’, ‘NITU’, ‘ECOPALM021’ and ‘NUA99’) collected from IRAD-Cameroon and four plant spacing distances (10 cm x 10 cm, 15 cm x 15 cm, 20 cm x 20 cm and 30 cm x 30 cm) corresponding respectively to four plant density (121, 49, 36 and 16 plants/m2) were evaluated for twelve quantitative traits in a randomly completed block design with three repetitions. ANOVA and correlation analysis were performed. Means values of each trait from the ANOVA analysis was submitted to the Tukey test at 5% probability level. The effect of variety was significant for all the twelve studied traits except the number of seed per plant. Pod length, plant height, number of seeds per pod and 100 seed weights were not affected by plant density while the numbers of seeds per plant, number of pods per plant, biological and seed yield were significantly affected by plant density. Interaction effect of plant variety and plant density on seed yield, biological yield, number of pods per plant and collar diameter was significant. No positive correlation was found between plant density and any of the studied traits. Leaf width, collar diameter, number of functional leaves and number of pods per plant inversely correlated with plant density. At the lowest plant density (16 plant/m2), seed yield and biological yield correlated poorly with related quantitative traits comparing to higher plant densities. From all the studied varieties, only ‘ECOPALM021’ showed the seed yield not affected by plant density. This study also showed that the higher seed yield and important biological yield was at 16 plants/m2 plant density.