Agronomic Biofortification of Wheat With Zinc and Iron Under Different Nitrogen Regimes

Abstract

Low available zinc (Zn) and iron (Fe) concentrations in about 50% of the global land resulted in Zn and Fe deficiency of cereal grains. Nitrogen (N) fertilization not only increase the wheat grain yield but also facilitate the uptake of Fe and Zn in wheat grain. Improving N availability to plants brings significant increase in shoot Fe content and uptake and accumulation of Zn in wheat plants. Thus, an experiment was conducted at the Cereal Crop Research Institute (CCRI) Pirsabak, Noweshera, Khyber Pakhtunkhwa, Pakistan during 2014-15 and 2015-16 to study the response of wheat to N, Zn and Fe (micro-nutrients, MN) application. Treatments included three levels of N (90, 120 and 150 kg ha-1), three concentrations of Zn and Fe (i.e. 1, 2, 3 kg ha-1) each along with two controls i.e. no micro nutrients no water (unsprayed check) and no micro nutrients + water (sprayed check). The N was soil applied and MN was applied as foliar spray at booting stage. The experiment was arranged in RCBD, with four replications. Days to anthesis, leaf area tiller-1, leaf area index, plant height, days to physiological maturity, spike m-2, grains spike-1, thousand-grains weight, biological yield, grain yield, harvest index, grain Zn-concentration, grain Fe-concentration, grain protein content, grain gluten content were significantly increased by both N and Zn while the same parameters except days to anthesis, days to physiological maturity and spike m-2 were also significantly enhanced by using Zn. The use of Zn (3 kg ha-1) and Fe (1 kg ha-1) with 120 kg ha-1 of N significantly improved the grain yield (34.6%) of wheat over unsprayed check. The use of Zn and Fe at the rate of 3 kg ha-1 each with 150 kg ha-1 of N improved the grain quality parameters i.e. grain protein (24.5%), grain gluten (23%) and Fe content (29%) of wheat grains over unsprayed check. Application of Zn and Fe at the rate of 3 and 1 kg ha-1, respectively with 150 kg ha-1 of N resulted in increased grain Zn concentration (58%) of wheat over unsprayed check. It was concluded that wheat grain yield can be enhanced by using nitrogen at the rate of 120 kg ha-1 with Zn and Fe at the rate of 3 and 1 kg ha-1, respectively. The same combination also proved to be cost effective as compared to other treatments studied. However, quality wheat grains can be produced by applying Zn and Fe at the rate of 3 kg ha-1 each with 150 kg ha-1 nitrogen.