Effect of Conventional and Nano Zinc Application on Growth, Yield and Nutrient Uptake of Cowpea

Abstract

Cowpea is a valuable and dependable commodity, generating income for producers and traders. Zinc (Zn) plays a crucial role in various biochemical processes, including enzyme activation, protein synthesis and hormone regulation. This research was conducted with the objectives to study the effect of conventional and nano zinc application on growth, yield and nutrient uptake of cowpea. A field experiment to assess the effect of conventional and nano zinc application on growth, yield and nutrient uptake of cowpea (Vigna unguiculata L.) was carried out in the Eastern dry zone of Karnataka at ICAR-Krishi Vignana Kendra, Hadonahalli, during Kharif 2023. The experiment was laid out in an RCBD with ten treatments replicated thrice. Among the treatments T10 (RDF + Soil application of ZnSO4 at 5 kg ha-1 + 0.4% nano zinc spray at 40 DAS) recorded significantly higher soil nutrient availability, growth, yield and nutrient uptake compared to the control. This treatment recorded superior plant height (61.93 cm), number of leaves (13.40) and yield attributes such as number of pods per plant (22.12) and seed yield (1733.45 kg ha-1).  Higher uptake of nutrients viz., N (70.54 kg ha-1), P (11.44 kg ha-1) and K (21.67 kg ha-1) by cowpea was recorded with RDF + Soil application of ZnSO4 at 5 kg ha-1 + 0.4% nano zinc spray @ 40 DAS. Significantly lower uptake of these nutrients was noted in the control. The combined soil with foliar application increases the zinc use efficiency. Soil application offers a consistent nutrient supply to plant roots, while foliar application rapidly delivers nutrients directly to the leaves. This dual approach ensures efficient nutrient uptake, as the plant benefits from both soil and foliar sources.