Effect on the Growth Rate of Sweet Corn through Zinc and Iron biofortification under Temperate Ecology of Kashmir

Abstract

A two-year field experiment was conducted during the kharif seasons of 2024 and 2025 at the Agronomy Research Farm, Faculty of Agriculture, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir (SKUAST-K), to evaluate the effects of foliar zinc (Zn) and iron (Fe) application on the growth dynamics of sweet corn (Zea mays L.). The experiment was laid out in a randomized complete block design (RCBD) with 13 treatments and three replications. The treatments comprised a control (T₁), chelated Fe at 0.25, 0.50 and 0.75% (T₂–T₄), FeSO₄ at 0.25, 0.50 and 0.75% (T₅–T₇), chelated Zn at 0.25, 0.50 and 0.75% (T₈–T₁₀), and ZnSO₄ at 0.25, 0.50 and 0.75% (T₁₁–T₁₃). The recommended dose of N:P₂O₅:K₂O (150:80:60 kg ha⁻¹) was applied uniformly to all treatments, while foliar micronutrient application was performed at the knee-height stage. Sweet corn variety ‘Sugar 75’ was transplanted at a spacing of 60 cm × 20 cm. Crop growth was assessed at different growth intervals using crop growth rate (CGR), relative growth rate (RGR) and net assimilation rate (NAR). During 30–60 days after transplanting (DAT), chelated Zn treatments showed the most pronounced response. Chelated Zn @ 0.75% (T₁₀) recorded the highest CGR (49.99 g m⁻² day⁻¹) and RGR (0.1084 g g⁻¹ day⁻¹), whereas NAR was highest with chelated Zn @ 0.50% (T₉), reaching 2.04 g m⁻² day⁻¹. Iron treatments produced moderate but consistent improvements over the control, although their performance remained lower than that of the zinc treatments. CGR, RGR and NAR declined during 60–90 DAT across treatments, reflecting the progression of crop development; however, zinc-treated plants generally maintained a relative advantage. The results indicate the potential of foliar-applied chelated Zn, particularly at 0.50–0.75%, to enhance the physiological growth efficiency of sweet corn under temperate agro-ecological conditions.