Effect of Irrigation, Phosphorous and Potassium Application on Root Traits, Soil Microbial Growth and Physiology of Green Gram

Aims: To manage the implication of irrigation water at different growth stages coupled with basal phosphorus and foliar potassium application targeting to reduce water stress.

Study Design: Split split-plot design.

Place and Duration of Study: Agricultural Research Station, Chatabar, Odisha. India, during 2022-2023 cropping season.

Methodology: Three irrigation treatments in main plots (I1, I2 and I3) - I1 included three irrigations at vegetative, flowering and pod formation periods, I2 skipped one irrigation at pod formation and I3 skipped at flowering. Sub-plot consisted of phosphorus fertilizer treatments (P1, P2 and P3) providing 100, 85 and 115% recommended dose of P. In sub sub-plots- 2% foliar spray of KCl at vegetative and flower initiation periods. The parameters recorded soil moisture depletion, root traits, microbiological parameters, plant physiological parameters and grain yield.

Results: The depletion of soil moisture increased with crop growth; I3 depleted at a maximum rate (4.5 mm d-1) followed by I2 (4.1 mm d-1). The enhanced availability of root zone soil moisture improved microbial biomass carbon (MBC) and dehydrogenase activity (DHA). The I1 improved the maximum root tips, forks and crossings; while I3 reduced an overall of 131% of the root traits than I1. The crop growth rate (CGR) and leaf area index (LAI) were also improved according to soil moisture availability; however, I2 merely decreased 8 and 13% in CGR and LAI as compared to I1. P3 improved the maximum of the soil microbiology (MBC and DHA), root improvement and plant physiology. I1P3 produced the highest grain yield of 9.06 q ha-1, although, I2P3 produced was just 7% lower than I1P1.

Conclusion: The application of three irrigation produced maximum grain yield; while the skipping of one irrigation at pod formation stage with 15% higher P application could provide satisfactory yield where availability of irrigation water is limited.