Enhancing vegetable cowpea growth and yield in semi-arid regions: Effect of liquid microbial consortia and variable nitrogen doses under saline and canal water irrigation

A 2-year experiment was undertaken to assess the impact of irrigation water quality, nitrogen doses, and microbial inoculants on soil nutrient availability, plant growth parameters, and green pod yield of cowpea in the semi-arid region of Punjab, India. Irrespective of other factors, nitrogen levels significantly influenced available N, P, and Fe in both years and across years when pooled, while Mn content was notably affected only when data were combined across years. Elevated soil pH, EC, K, and micronutrients (Fe, Cu, Zn, and Mn) were observed in saline water irrigated plots in both years and across pooled data, whereas available N and P were high in canal water irrigated plots. Microbial inoculants reduced soil pH and EC while enhancing soil nutrient availability. Canal water irrigation, regardless of other variables, increased plant height by 13.9%, 16.4%, and 15.1%, pods per plant by 6.0%, 5.9%, and 2.7%, pod length by 6.1%, 4.3%, and 5.2%, and green pod yield by 114.4%, 118.0%, and 116.3% in 2019, 2020, and pooled years. Decreasing nitrogen levels also reduced pods per plant by 6.9%, 6.8%, and 6.7%, pod length by 10.6%, 11.8%, and 11.2%, and green pod yield by 8.6%, 7.2%, and 7.8% in 2019, 2020, and pooled years, regardless of other factors. Likewise, liquid bio-fertilizers, either alone or in combination, significantly affected pods per plant by 16.6%, 18.6%, and 17.5%, pod length by 26.4%, 28.1%, and 27.3%, and green pod yield by 12%, 32.82%, and 14.2% in 2019, 2020, and pooled years, irrespective of other factors.