Zinc biofortification of dual-purpose cowpea Vigna unguiculata (L.) Walp. for enhancing the productivity and nutritional quality in a semi-arid regions of India

摘要

ABSTRACT Zinc deficient soils cause low crop production leading to malnutrition in humans and livestock. Two years field experiments were conducted on cowpea crop with six ZnSO4·H2O (33) treatments viz. no Zn, soil application of 16 kg ZnSO4·H2O ha−1 (SZn), one foliar spray of 0.3 ZnSO4·H2O at early bloom (EB) stage (F1Zn), two foliar sprays of 0.3 ZnSO4·H2O at EB and full bloom (FB) stages (F2Zn) and combination of soil application + foliar sprays of ZnSO4.H2O (SZn+F1Zn and SZn+F2Zn) were tested. The results showed that soil application of 16 kg ha−1 of ZnSO4·H2O followed by two foliar sprays of 0.3 ZnSO4·H2O at EB (R1) and FB (R2) stages recorded maximum increase in grain yield (43.7) and grain Zn content (22.7) over control. However, in straw, a three-fold increase in Zn content was recorded. Foliar applications of 0.3 ZnSO4·H2O at EB and EB+FB stages recorded a significant increase in grain (8.2 and 11.4) and straw Zn content (63.0 and 104.0) over control. In conclusion, combination of soil (SZn) + foliar (F2Zn) Zn application method was most remunerative with maximum production and monetary efficiencies (15 kg ha−1 day−1 and $7.5 ha−1 day−1) and is an effective approach for grain and straw Zn biofortification in cowpea.