Efficacy of Nitrogen and Zinc Application at Different Growth Stages on Yield, Grain Zinc, and Nitrogen Concentration in Rice

Abstract

Zinc (Zn) is an essential element involved in human metabolism, which can be supplied by an appropriate diet. Enhancing Zn enrichment in rice grains through agronomic biofortification is advocated as an immediate and effective approach to combat micronutrient malnutrition in hu-man. It has been well-documented that high grain Zn accumulation in rice can be achieved by Zn fertilizers management. This study evaluated the effects of foliar nitrogen (N) and Zn applied at the flowering and milky stages of brown rice plants with and without soil Zn application. A glasshouse pot experiment was conducted using a completely randomized design with four replicates. Soil Zn in the form of ZnSO4 was applied at 0 and 50 kg ha−1. Foliar fertilizer of 1% urea along with 0.5% ZnSO4 was applied and assigned as (1) nil foliar N and Zn (N0Zn0), (2) foliar N with nil Zn (N+Zn0), (3) nil foliar N with foliar Zn (N0Zn+), and (4) foliar N and Zn (N+Zn+) at flowering and milky stages. Foliar application of N and Zn increased grain yield and yield components in both soil Zn conditions. Grain Zn concentration in brown rice was the highest when foliar N and Zn were applied under nil soil Zn conditions; however, grain N concentration decreased by 13.1–28.5% with foliar application at flowering and 18.8–28.5% with application at the milky stage. The grain Zn content was increased by foliar application of N0Zn+ and N+Zn+ at flowering and milky stages. Applying foliar N and Zn at flowering or milky stages tended to increase the grain N content when Zn was applied to the soil, while nil soil Zn decreased the N content by 26.8% at flowering and milky stages under N0Zn+. The results suggest that the milky stage is the most suitable for foliar application of Zn for increasing (i) grain yield and (ii) N and Zn concentrations in brown rice without having a dilution effect.

The Potential Role of Zinc and Silicon in Improving Grain Yield and Lodging Resistance of Rice (Oryza sativa L.)

“…The maximum rice yield was attained while applying 40 kg ha −1 of Zn, and further increment in Zn treatment (i.e., 80 kg ha −1 ) led to a decline in yield at Qionghai. Such results are in conformity with the available literature, which suggests that within a particular range, a substantial positive association can be found between rice yield and Zn rate; however, excessive Zn applications are detrimental to rice and may not help in increasing yield [34]. Our results also depicted a similar trend, as by applying Zn, not only grain yield but other associated traits such as panicles m −2 , spikelets m −2 , and aboveground biomass were increased when compared with no Zn fertilizer.…”

Effects of Returning Green Manure-Chinese Milk Vetch on the Availability and Transformation of Zinc in Purple Tidal Mud Soil under Rice Cultivation

“…The extent of the impact also varied at different sampling periods. By the end of the experiment, compared to the H treatment, the H+Z, H+1.5Z, H+2Z, and H+2.5Z treatments resulted in a decrease in Ex-Zn content in purple tidal mud soil by 0.79%, 4.80%, 12.00%, and 15.19% respectively; Wbo-Zn decreased by 14 Incorporating Chinese milk vetch alone can increase the content of Ex-Zn, Wbo-Zn, Carb-Zn, OxMn-Zn, and Min-Zn in purple tidal mud soil, while decreasing the content of Sbo-Zn. However, when Chinese milk vetch is incorporated after chemical fertilization, it leads to a decrease in the content of Ex-Zn, Wbo-Zn, Carb-Zn, and Sbo-Zn in purple tidal mud soil.…”

“…Increasing the zinc content in rice grains would contribute to improving consumers' zinc intake [13]. Agronomic biofortification, aimed at enhancing the zinc content in rice grains, is considered a direct and effective approach to addressing human zinc deficiency [14].…”

How Does Zinc Improve Salinity Tolerance? Mechanisms and Future Prospects

“…For instance, Chattah et al [ 232 ] reported that applying Zn at the booting and milking stages was an important practice to improve rice growth, quality, and productivity. Likewise, Tuiwong et al [ 233 ] found that foliar Zn application at the flowering and milking stages substantially improved growth and productivity. Recently, Nafees et al [ 234 ] reported that Zn applied at two weeks of germination mitigated the toxic effects of salinity (MDA and H 2 O 2 production) and improved the growth of wheat by increasing antioxidant activities and osmolytes accumulation.…”