Effect of Rhizobium inoculation and urea dosage on the growth and yield of mung bean (Vigna radiata L.)

Optimizing nitrogen management by integrating biological nitrogen fixation (BNF) with mineral fertilizers is crucial for sustainable mung bean ( Vigna radiata L.) production in tropical regions. This study was conducted at the Agro Techno Center (ATC), Sriwijaya University, South Sumatra, Indonesia, using polybags filled with a mixture of soil and cow manure (4:1, w/w). The experiment evaluated the interaction of Rhizobium inoculation and urea application on mung bean growth, physiology, yield components, and productivity using a factorial randomized block design (RCBD) with two factors: Rhizobium dosage (0, 5, 15, and 25 g kg⁻ 1 seed) and urea dosage (25, 50, and 75 kg ha⁻ 1 , equivalent to 11.5, 23, and 34.5 kg N ha⁻ 1 ). Results showed that vegetative growth parameters increased linearly with plant age but were not significantly affected by treatments during early stages, indicating that nitrogen was not initially limiting. However, Rhizobium inoculation significantly affected shoot biomass and several yield-related traits. Medium to high Rhizobium doses (15–25 g kg⁻ 1 seed) increased productivity by approximately 12% compared to the control and enhanced shoot biomass and key yield components, particularly the number of seeds per pod and seed weight per plant. Urea application also significantly affected pod fresh weight, pod dry weight, seed weight, and productivity, although its effects were less consistent across the measured growth and yield parameters. Principal component analysis (PCA) indicated an association between higher Rhizobium doses and productivity-related variables, indicating that yield improvement was primarily associated with seed weight and the number of seeds per pod rather than increased pod number. These findings indicate that both Rhizobium inoculation and urea fertilization contributed to mung bean yield formation, with Rhizobium showing broader effects across the measured parameters under the tested conditions, highlighting the importance of integrated nitrogen management for sustainable legume production.