Phosphorus and Zinc Fertilization Improve Zinc Biofortification in Grains and Straw of Coarse vs. Fine Rice Genotypes

Abstract

Continuous cropping of rice (Oryza sativa L.) and wheat (Triticum aestivum L.) deplete soil fertility and reduce crop productivity as well as zinc (Zn) concentrations in rice grains and straw. Low Zn concentrations in rice grains have a negative impact on human health, while low Zn concertation in rice straw creates a nutritional problem for animals. The current high yielding rice varieties and hybrids remove large quantities of Zn from the soils, lowering the residual concentrations of soil Zn for the subsequent crop (e.g., wheat). Field experiments were conducted on farmers field in Malakand with the objective to evaluate the impact of various combinations of phosphorus (0, 40, 80, and 120 kg ha−1) and Zn levels (0, 5, 10, and 15 kg ha−1) on biofortification of Zn in grains and straw of rice genotypes [fine (Bamati-385) vs. coarse (Fakhre-e-Malakand and Pukhraj)]. The results revealed that Zn biofortification in rice genotypes increased with the integrated use of both nutrients (P + Zn) when applied at higher rates (80 and 120 kg P ha−1, and 10 and 15 kg Zn ha−1, respectively). The biofortification of Zn in both grains and straw was higher in the coarse than fine rice genotypes (Pukhraj > Fakhre-e-Malakand > Basmati-385). It was concluded from this study that the application of higher P and Zn levels increased Zn contents in rice parts (grains and straw) under the rice-wheat system. We also concluded from this study that Zn concentrations in rice grains and straw are influenced by plant genetic factors and Zn management practices.

Role of Mycorrhizal Pathways in Plant Phosphorous and Zinc Uptake

“…Likewise in straw, the minimum Zn concentration in rice is (19.72 mg Kg -1 ) with the application of P @40 Kg ha -1 . With increasing P levels from 80 to 120 Kg, ha -1 increased grain Zinc concentration in both grains and straw [84]. In contradiction to the application of the above result of P resulted in the decline in Zn in both the shoots and roots.…”

“…Under the rice (Oryza sativa L.) wheat (Triticum aestivum L.) system the use of higher P and Zn levels increased in rice grain and rice straw. Plant genetic and crop management factors both influenced the Zn uptake under the rice-wheat farming system (Amanullah et al 2020). In a study, a hypothesis is raised whether the response of native and soilapplied P and Zn and its severity depends on soil properties or not.…”

“…Continuous uptake of Zn from the soil caused a deficiency in wheat and rice grain and straw content of Zn. Also, there is decreasing the residual concentration of Zn amount in the soil due to continuous cropping of rice and wheat hybrid varieties (Amanullah et al, 2020). Integrated application of Zn and P @ 10 and 15 Kg/ha Zn and @ 80 and 120 Kg/ha P is recommended respectively.…”

“…For example, coarse rice varieties are more responsive to Zn biofortification than fine rice varieties [84]. The plant absorbs Zn as a cation (Zn 2+ ) and P in the form of anions of H 2 PO 4 -1 or HPO 4 -2 [84].…”

“…For example, coarse rice varieties are more responsive to Zn biofortification than fine rice varieties [84]. The plant absorbs Zn as a cation (Zn 2+ ) and P in the form of anions of H 2 PO 4 -1 or HPO 4 -2 [84]. There are attractions between these two cations and anions to form chemical bonds both in the soil and plant.…”