Effects of Rhizobial and Non-rhizobial Bacterial Isolates from Legume Root Nodules on the Growth of Maize (Zea mays L.) in Umudike, Abia State, Nigeria

Abstract

The increasing dependence on chemical fertilizers in Nigeria has resulted in soil degradation, nutrient depletion, and environmental, necessitating sustainable alternatives like microbial biofertilizers. This study evaluated the effects of bacterial isolates obtained from the root nodules of selected leguminous plants on the growth of maize (Zea mays L.), contributing to sustainable agriculture and ensuring a healthier environment for future generations. Thirteen bacterial isolates were obtained from root nodules of beans, groundnut, soybean, sensitive plant and butterfly pea, using selective media including Yeast Extract Mannitol Agar, Ashby’s Mannitol Agar, Nitrogen-Free Malate Agar, and Nitrogen-Free BG-11 Agar. The isolates were morphologically and biochemically characterized, and formulated into liquid biofertilizers applied at 5.00ml and 10.00ml volumes to maize seedlings in a completely randomized pot experiment with untreated plants as control. Growth parameters including plant height, number of leaves, leaf area, internode length, and number of cobs were measured at two-week intervals up to 14 weeks. Data were analyzed using analysis of variance (ANOVA), and treatment means were separated using Duncan’s Multiple Range Test at 5% significant level. The results showed significant differences among treatments for all parameters measured. At 14 weeks, T3 (5.00ml) recorded the highest plant height (104.43 ± 25.06 cm), number of leaves (13.67 ± 2.05), leaf area (291.71 ± 33.12 cm²), internode length (5.37 ± 0.48 cm) and number of cobs (1.67 ± 0.40), all significantly exceeding the control values. The findings demonstrate that bacterial isolates from legume root nodules significantly enhanced maize growth and reproductive performance compared to the untreated control. However, molecular identification using 16SrRNA sequencing was not conducted and is recommended for accurate taxonomic confirmation The superior performance of the 5.00ml treatments, particularly T3, demonstrates the potential of indigenous bacterial biofertilizers as effective, eco-friendly inputs for sustainable maize production and reduced reliance on chemical fertilizers.