Effect of Fertility Levels and Biofertilizers on Growth and Yield of Cowpea (Vigna unguiculata L.) in the Semi-Arid Region of Rajasthan, India

Abstract

A field experiment was conducted during the Kharif season of 2018 at the Agronomy Farm, MJRP College of Agriculture & Research, Achrol, Jaipur (Rajasthan), to study the effects of different fertility levels and biofertilisers on the growth and yield of cowpea (Vigna unguiculata L.). The experiment was laid out in a Factorial Randomised Block Design (RBD) with three replications, comprising sixteen treatment combinations of four fertility levels [Control (F₀), 50% RDF (F₁), 75% RDF (F₂), and 100% RDF (F₃)] and four biofertiliser treatments [Control (B₀), Rhizobium (B₁), PSB (B₂), and Rhizobium + PSB (B₃)]. Cowpea variety RC-101 was sown at a spacing of 30 cm × 10 cm with a seed rate of 20 kg ha⁻¹. Growth parameters, yield attributes, and yields were significantly influenced by both fertility levels and biofertiliser application. Among fertility levels, 100% RDF recorded the maximum plant height (67.72 cm), number of branches per plant (9.50), dry matter accumulation (118.63 g plant-1), chlorophyll content (2.61 mg g⁻¹), pods per plant (9.21), seeds per pod (8.34), seed yield (1042 kg ha⁻¹), straw yield (1961 kg ha⁻¹), biological yield (3003 kg ha⁻¹), and harvest index (34.54%), which were statistically at par with 75% RDF but significantly superior to lower fertility levels. Among biofertilisers, the combined inoculation of Rhizobium + PSB consistently outperformed individual inoculations and the un-inoculated control, producing the highest seed yield (1056 kg ha⁻¹), which was 47.33% higher than the control. Test weight (1000-seed weight) was not significantly influenced by either factor. Interaction effects between fertility levels and biofertilisers were non-significant for all parameters, indicating additive effects. The study concludes that the application of 75–100% RDF along with combined inoculation of Rhizobium + PSB significantly enhances growth, yield attributes, and seed yield of cowpea under semi-arid conditions of Rajasthan. However, considering economic viability and resource efficiency, the treatment combination of 75% RDF + Rhizobium + PSB is recommended for sustainable cowpea production in the region.