Compared with continuous flooding, the water-saving irrigation can increase water use efficiency. However, the effects of water-saving irrigation on yield and quality in rice paddies have not been clearly defined. The objective of this study was to identify the systematic effects of water-saving irrigation on rice yield and quality through Meta-analysis techniques.
In the present study, a total of 34 studies that adapted a water-saving treatment and continuous flooding as the control involving 263 paired observations were included across this dataset. The meta-analysis was conducted to identify the responses of yield and quality to water-saving irrigation as affected by experimental type, water-saving irrigation type, cropping system, rice type, the period of water-saving irrigation, soil total nitrogen (N), soil texture, N rate, and the number of N application.
Overall, the water-saving irrigation did not significantly affect grain yield and quality relative to continuous flooding. In terms of water-saving irrigation type, the moderate water-saving irrigation increased brown rice rate (+0.9%), milled rice rate (+1.5%), and head milled rice rate (+2.3%), but did not affect grain yield, chalkiness percentage, chalkiness degree, length/width ratio, amylose content, gel consistency, and protein content relative to continuous flooding. However, the severe water-saving irrigation significantly decreased grain yield (-22.1%), brown rice rate (-2.7%), milled rice rate (-2.7%), and head milled rice rate (-3.6%), and increased chalkiness percentage (+28.0%) and chalkiness degree (+46.7%), while no marked differences were observed on length/width ratio, amylose content, gel consistency, and protein content. Furthermore, compared with continuous flooding, the water-saving irrigation reduced protein content (-9.8%) of late rice, but did not affect that of early rice, middle rice, and single rice.
Compared with continuous flooding, the moderate water-saving irrigation could improve rice milling quality, and did not affect grain yield, appearance quality, cooking and eating quality, and nutrition quality. The severe water-saving irrigation significantly reduced rice yield, milling quality, and appearance quality, while no significant effects were found on cooking and eating quality and nutrition quality. The results provided an insight to evaluate the responses of grain yield and quality to water-saving irrigation.