Effect of Plant Density, Phosphorus and Rhizobium Inoculant on Growth and Yield of KAT B1 and GLP 585 Beans in Medium Potential Agro Ecological Zones of Imenti South, Kenya

Abstract

Common bean (Phaseolus vulgaris (L) is adapted to different agro ecological zones. Its genetic makeup and agronomic practices affects their growth and production. Some farmers have grown bean varieties not bred for certain localities with minimal or no understanding of their agronomic practices. Bean variety KAT B1 bred for lower agro ecological zones perform well in medium agro ecological zones despite its agronomic practices being less understood by farmers. Therefore, this study sort to determine the effect of plant densities, phosphorus and rhizobium inoculum on growth of KAT B1 and Red Haricot beans in medium agro ecological zones. Field experiments were conducted for two seasons i.e., October - December 2021 and March – May 2022 at Kaguru Agricultural Training Centre, Imenti South, Kenya. A 3 x 2 x 2 x 2 factorial experiment was laid out in a randomized complete block design with three replications. There were four factors; plant densities (111,111, 166,666 and 222,222 plants/ha), two common bean varieties (KAT B1 and Red Haricot GLP 585), rhizobium inoculum (0g and 100g/ha) and rock phosphate fertilizer (0 kgP/ha and 60 kgP/ha). Data collected on chlorophyll content, number of leaves and branches were subjected to analysis of variance using SAS version 9.4 and significant means separated using LSD at α= 0.05. Treatment R0V1D1P0 and R0V2D2P0 recorded the least chlorophyll content and number of leaves across the growth stages in both seasons. Similarly, treatment R1V1D3P1 and R1V2D2P1 recorded the highest chlorophyll content and number of leaves across the growth stages in both seasons at 7, 14, 21, 28 and 35 days after sowing (DAS). Treatment R0V1D1P0 recorded the least number of branches (0.50 and 0.79; 2.16 and 2.70) while treatment R0V2D2P0 also recorded the least number of branches (0.54 and 1.04; 2.12 and 2.82l) in season 1 and 2 respectively. Treatment R1V1D3P1 recorded the highest number of branches (2.34 and 3.58; 3.12 and 4.04) while treatment R1V2D2P1 also recorded the highest number of branches (2.58 and 4.91; 3.29 and 4.12) produced across the growth stages at 28 and 35 DAS in season 1 and 2, respectively. GLP 585 gave the highest yield 3.037 tonnes/ha in treatment R1V2D2P1 compared to KAT B1 yield of 2.670 tonnes/ha in treatment R1V1D3P1. Therefore, incorporation of rhizobium inoculant and rock phosphate fertilizer is recommended in common beans to increase yield and enhance food security.