Influence of phosphorus and bio-fertilizers on growth and yield of cowpea [Vigna unguiculata (L.) Walp.] in acidic soil of NEH region of India

A field experiment was carried out on cowpea (Vigna unguiculata (L.) variety Kashi Kanchan during summer season at the experimental farm, department of Vegetable Science, College of Horticulture and Forestry, Central Agricultural University, Pasighat, Arunachal Pradesh. The experiment was laid out in factorial complete randomized block design with 12 treatments i.e. three levels of phosphorus [control 0 kg(P0), 20 kg (P1) and 40 kg (P2) /ha] and four levels of bio-fertilizer [control (B0), Rhizobium10 ml/kg seed(B1), PSB 10 ml/kg seed (B2) and Rhizobium + PSB both 10 ml/kg seed (B3)] with three replications. The uniform dose of nitrogen (N) and potassium (K) @ 20 kg/ha along with 10 t/ha FYM (Farm Yard Manure) were applied to all the treatments. Result indicated that the application of P2 (40 kg P/ha) significantly increased the plant height, leaf area index, stem girth, number of nodules per plant, number of branches per plant , total dry matter, pod yield, available soil nutrient status viz., pH, N, P, K, organic carbon and NPK content in plant after harvesting. Similarly, seed inoculation with B3 (Rhizobium + PSB) significantly enhanced the growth, yield, soil nutrient status and nutrient content in plant over single inoculation of Rhizobium and PSB. Combined inoculation of seed with Rhizobium + PSB (B3) along with 40 kg P/ha (P2) significantly increased the stem girth (1.84 cm), total dry matter (13.91g/plant), green pod yield (196.37g/plant and 120.90q/ha), soil nutrient status viz., pH(6.20), available N (370.89 kg/ha), available P (38.57 kg/ha), available K (168.77 kg/ha), organic carbon (2.80%) and N, P and K (0.17%, 0.16% and 0.39%) content over rest of treatment combination.