Imposed Water Deficit after Anthesis for the Improvement of Macronutrients, Quality, Phytochemicals, and Antioxidants in Rice Grain

The control of protein and amylose content is the principal challenge in rice nutrient and quality improvement. In this study, water deficits in 2- and 3-day intervals were imposed on two Japonica cultivars K1 and K3, and an Indica K4 subtype after anthesis to harvest. It was observed that although rice yield was affected, the protein content was increased 6.53–6.63% to 9.93–10.16%. The amylose quantity was reduced significantly from 22.00–22.43% to 16.33–17.56%, while fatty acids in rice grain were not influenced. Total anthocyanins were greatly promoted by 53.1% as compared to the non-treated trials. The antioxidant capacity in rice grain increased up to 59.1% in 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and 41.6% in reducing power assays. Findings of this research revealed that the 3-day interval of water deficit imposition was the most effective to improve rice macronutrients and quality, as well as beneficial phytochemicals and antioxidants in rice grain. The water control after anthesis to harvest in rice cultivation is beneficial and economical for farmers to improve rice nutrients and quality, thus contributes to the sustainable rice production in many developing countries.