Inoculation of Common Bean Varieties

We carried out an experiment in a screen house to determine the mineralization potential and phenotypic characteristics of selected isolates. Common bean varieties from Kenya Seed Company (Rose coco and Mwitemania) were used as test crops for total plant biomass. This was carried out by inoculating two high-potential PSB (KB5 and KV1) into two varieties of common bean to determine their efficacy. Certified bean seeds were surface sterilized with 1% mercuric chloride for 3 minutes followed by rinsing with distilled water and pregermination in a darkroom using Petri dishes. Inoculants were prepared according to [26 (link)]. The isolates were grown in NBRIB broth for 2 days and cells were harvested by centrifugation at 5000 × g for 20 min. The cells were resuspended with sterile distilled water to give a final concentration (10⁸ CFU ml⁻¹) in a 250 mL conical flask. The seedlings' roots were immersed into the culture for 5 minutes and covered uniformly with a 15 mm thick layer of vermiculite in a Leonard's Jar and then placed into a completely randomized design alongside negative control (uninoculated seedlings). A total of six treatments were replicated four times to obtain 24 experimental units with two trials. Leonard's jars assemblies [37 (link)] (9 cm diameter and 12 cm height) were filled with the sterile vermiculite (Kenworks, Nairobi, Kenya). Tricalcium phosphate was provided as soil inorganic phosphorus fertilizer at the rate of 150 mg/kg based on the nutrient necessities of common bean plants [38 (link)]. Depth (5 cm) was dug into Leonard's Jar, and two seedlings were placed at equal distances. A modified nutrient solution without phosphorus was supplied to all treatments [39 ]. After 6 weeks, plant samples were uprooted and oven-dried at 70°C to a constant weight and were grinded after drying to determine the total dry weight in grams.