Promising Role of Moderate Soil Drying and Subsequent Recovery Through Moderate Wetting at Grain-Filling Stage for Rice Yield Enhancement

The study was conducted at the grain-filling stage to elucidate the physiological and molecular mechanisms of the root to enhance yield under alternate wetting and drying (AWD) compared with conventional irrigation. Measurements of root dry weight (RDW), seed setting rate, total kernel weight, and grain yield were determined along with 2D electrophoresis to detect altered protein expression in response to moderate soil drying (MD) and the subsequent recovery phase as moderate wetting (MW) under AWD compared with continuous wetting under CI. We found significant enhancement in RDW as well as 14.30 % increase in inferior spikelets , seed setting and 10.32 g m −2 increase in final yield. Among the total 55 differentially expressed proteins, 26 proteins were differentially expressed under both MD treatment and MW treatment, whereas 14 proteins under MD and 15 proteins under MW showed distinct expression. Differentially expressed proteins were involved in redox homeostasis, signaling, defense, energy, photoassimilate remobilization and included 14-3-3 proteins, cysteine-rich receptor-like protein kinase, monodehydroascorbate reductase, ascorbate peroxidase, glutathione S -transferases, translationally controlled tumor protein, remorin C-terminal domain containing protein, protein disulfide isomerase, DnaK family protein, cysteine synthase, aminotransferase, phosphoglycerate mutase, pyruvate phosphate dikinase, ATP synthase, and abscisic acid stress ripening (ASR1). The differential expression ratio of the signaling, redox, and defense group proteins was almost the same under MD and MW. ABA signaling, amino acid synthesis, and N remobilization were upregulated under MD, and the enzymes involved in carbohydrate, energy, and transportation metabolism were upregulated under MW. In conclusion, at the rice grain-filling stage, AWD is a potential technique to trigger signaling and the enzymatic protein network for systematic senescence initiation, root enlargement for maximum nutrient uptake, and maximize photoassimilate remobilization for yield enhancement.