Studies on foliar application of zinc as bio-fortification strategy to enhance grain zinc content in rice (Oryza sativa L.) genotypes

Abstract

Zinc (Zn) deficiency is a concern for nearly half of the world population. Biofortification through foliar Zn application is an approach to reduce human Zn deficiency. Knowledge available on effect of foliar applied zinc towards biofortification efficiency and bioavailability of rice grain is limited. Pot experiment with rice was conducted to study the effect of foliar applied zinc along with soil application of recommended dose of N: P: K: Zn for rice. Two contrasting groups of four cultivars each with respect to seed zinc based on previous screening were selected (high seed zinc types and low seed zinc types). Zinc was applied in the form of ZnSO4.7H2O foliar application at vegetative stage and at reproductive stage in three different doses (recommended dose, 10% lower than recommended dosage and 10% higher than recommended dosage). Results suggest that foliar zinc application is effective in enhancing grain zinc when applied with recommended dose of soil zinc fertilizer irrespective of inherent zinc acquisition capacity by roots. Stem had higher Zn accumulation at 65 DAS indicating translocation of foliar applied zinc. At 50% panicle initiation stage, there was higher zinc in leaf compared to stem and developing grain implying Zn movement from stem to seed. Zn analyzed at different stages of grain filling till harvest showed an increase in Zn content both in high and low zinc types. Higher seed Zn was observed in long duration varieties. Using long duration varieties for foliar biofortification could be an effective strategy to overcome Zn deficiency.