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.
Highlights
Zinc is an essential micronutrient for growth and development, and it is involved in many of the major functions in plants including cell membrane structure, photosynthesis, hormone activity, lipid and nucleic acid metabolism, gene expression and regulation, protein synthesis, and defense against drought and disease [1,2]
In the wetland rice variety, CNT1, grain yield was 205.4 g m−2, which was a decrease of 18.0% in plants grown under the well-drained conditions compared to those grown in the waterlogged soil, but the grain yield of plants grown in the waterlogged soil only slightly decreased to
In CNT1, applying Zn fertilizer to plants resulted in a higher tiller number per plant than in plants without Zn fertilizer application when grown under well-drained soil, but the opposite result was found in the waterlogged conditions
Summary
Zinc is an essential micronutrient for growth and development, and it is involved in many of the major functions in plants including cell membrane structure, photosynthesis, hormone activity, lipid and nucleic acid metabolism, gene expression and regulation, protein synthesis, and defense against drought and disease [1,2]. The efficiency of Zn fertilizer application has been reported to depend on several factors, including fertilizer source, application time and method, and the soil’s chemical properties. The latter factor is influenced by water management [7]. The total Zn uptake into rice plants and grain Zn concentration were reported to be influenced by the ability of soil to supply Zn as well as by rice variety and water management [8]. A previous study found that alternate wetting and drying conditions increased grain yield and Zn concentration in both brown rice (unpolished) and white rice (polished) depending on the rice variety [9]. The waterlogged soil conditions could decrease the concentration of watersoluble Zn [14], while well-drained soil provides a favorable environment for the activity of mycorrhizal fungi, and enhanced mycorrhizal inoculation has been shown to increase plant Zn uptake [15]
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