Improving Grain Zinc Concentration in Wetland and Upland Rice Varieties Grown under Waterlogged and Well-Drained Soils by Applying Zinc Fertilizer

Abstract

The objective of this study was to evaluate the responses in grain yield and zinc concentration of wetland and upland rice varieties to Zn fertilizer application and different growing conditions. The wetland (Chainat 1; CNT1) and upland (Kum Hom CMU; KH CMU) rice varieties were grown under waterlogged and well-drained soil conditions with or without Zn fertilizer application. Zinc fertilizer (ZnSO4) was applied at 0 and 60 kg ha−1 in three stages at tillering, booting, and flowering. In the wetland variety, CNT1, grain yield decreased by 18.0% in the well-drained soil compared to the waterlogged conditions, but there was an 8.9% decrease in grain yield in the waterlogged soil compared to the well-drained soil in the upland variety, KH CMU. Applying Zn fertilizer affected yields differently between the varieties, decreasing grain yield by 11.9% in CNT1 while having no effect in KH CMU. For grain Zn concentrations in brown rice, applying Zn fertilizer increased Zn concentration by 16.5–23.1% in CNT1 and KH CMU under both growing conditions. In the well-drained soil, applying Zn fertilizer increased straw Zn concentration by 51.6% in CNT1 and by 43.4% in KH CMU compared with the waterlogged conditions. These results indicated that the wetland and upland rice varieties responded differently to Zn fertilizer application when grown in different conditions. Applying Zn fertilizer in the appropriate rice variety and growing conditions would help farmers to improve both the desirable grain yield and Zn concentration in rice.