Growth and Water Use between Conventional and Hybrid Rices as Impacted by Different Irrigations.

Background and Objective The decrease in available water resources for agriculture in the South of China has made developing water-saving irrigation essential for rice production. This paper investigates the impact of an improved irrigation method on growth and water use of conventional rice and hybrid rice. Method The experiments were conducted from 2018 to 2020 in plots within a paddy field in the Irrigation Experimental Station of Jiaxing Pinghu in Zhejiang province. The rice varieties Xiushui 134 (conventional) and Yongyou 9 (hybrid) were used as the model plants. They were irrigated by conventional flooding irrigation and thin-water film irrigation by keeping the topsoil just saturated. In each treatment, we measured the leaf area index, total dry matter, root growth, grain yield, and water demand and consumption of each rice variety. Result Water demand and consumption of both rice varieties under thin-water film irrigation were lower than that under flooding irrigation (P<0.01). Under flooding irrigation, water demand and consumption of both varieties during their whole growth period increased with the increase in precipitation, albeit the conventional rice consumed slightly less water than the hybrid variety (P>0.05). Compared with conventional flooding irrigation, thin-water film irrigation reduced average daily water consumption by 22.6%-59.5%, with the hybrid rice consuming 1.3%-3.0% more water than the conventional variety. Compared with flooding irrigation, thin-water film irrigation increased average rice yield by 1.7%, especially the hybrid variety whose yield was 31.9% higher than that of the conventional variety. Thin-water film irrigation reduced water consumption by 30.1%-35.0%, in addition to its significant increase in WUEI and WUEET. Due to the difference in yield between the two varieties, there was an interactive effect between the irrigation method and rice variety, with their WUEI, WUEP and WUEET differing significantly.Conclusion The thin water-film irrigation was effective to increase the development of leaf area and dry matter accumulation, especially for the hybrid variety. Water demand and consumption of both varieties were affected not only by annual precipitation and evaporation, but also by irrigation method, though no significant difference was found between the two varieties. [ABSTRACT FROM AUTHOR]