Effect of boron and zinc fertilization on growth and yield of cowpea (Vigna unguiculata Walp.) in inceptisols of Arunachal Pradesh

A field experiment was conducted with ten treatments to study the effect of boron (B) and zinc (Zn) in cowpea (Vigna unguiculata Walp.) in Inceptisols of Arunachal Pradesh. Recommended doses of fertilizers (RDF) applied was N, P2O5 and K2O @ 30, 60 and 50 kg ha-1, respectively. Growth parameters viz., plant height, branches per plant and dry matter yield were significantly influenced due to treatments effects. Maximum average plant height (55.8 cm), branches per plant (8.2) and dry matter yield (51.9 g plant-1) were recorded with application of RDF + 1.5 kg B ha-1 + 5 kg Zn ha-1 (T9). Nodules dry weight was significantly influenced by Zn treatment apart from B application. The highest amount of nodule formation (5.2 g plant-1) was recorded in T7 (RDF + 7.5 kg Zn ha-1). Maximum average seed yield (2.24 t ha-1) was also obtained in treatment T9 and minimum (1.41 t ha-1) in treatment T1 (RDF). The highest uptake of nitrogen (N) (180.5 kg ha-1), B (0.9 kg ha-1) and Zn (0.93 kg ha-1) was observed under treatment T9, whereas, the lowest uptake was observed under treatments T1. The maximum uptake of phosphorus (P) (20.4 kg ha-1) and potassium (K) (131.0 kg ha-1) was obtained with treatment T4 (RDF + 2 kg B ha-1) and least uptake of P (13.0 kg ha-1) and K (79.8 kg ha-1) was recorded under treatments T7 (RDF + 7.5 kg Zn ha-1). The soil organic carbon content, water holding capacity and available NPK significantly increased in most of the treatments after harvest of cowpea. However, the treatments had no significant influence on change of the soil pH.