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Water productivity, sink production and varietal differences in panicle structure of rice (Oryza sativa L.) under drip irrigation with plastic-film mulch

2022; Elsevier BV; Volume: 291; Linguagem: Inglês

10.1016/j.fcr.2022.108790

1872-6852

Junfa Wang, Oluwasegun Olamide Fawibe, Kehinde Oluwaseyi Fawibe, Akihiro Isoda,

Irrigation Practices and Water Management

Drip irrigation with plastic-film mulch (DI) has shown great potential as a water-saving technique for rice production; however, considerable variations exist in the response of rice varieties under the system. This study aimed to determine the specific attributes underlying the changes in the response of varieties under DI as compared with the outcome under continuous flooding (CF), and to identify breeding targets that could promote the yield of varieties cultivated under DI. Nine varieties of rice including upland varieties: Norin24 (Norin), Toyohatamochi (Toyo), Hitachihatamochi (Hitachi), and lowland varieties: Mitsuhikari2003 (Mitsu), Togohybrid 4 (Togo), Himenomochi (Hime), Akidawara (Aki), Hokuriku193 (Hoku), and Bekoaoba (Beko) were evaluated in a 2-year field experiment. Hoku and Beko are multipurpose high-yielding varieties that were developed for animal feed. Compared with CF, DI saved irrigation water by 54% and 64% in 2019 and 2020, respectively. In both years, the grain yields of varieties under DI and CF ranged from 308 to 789 g m-2 and 222–1033 g m-2, respectively. The difference in the yields of varieties under DI was attributed to the difference in the number of spikelets/m2 and sink capacity of the varieties. This was denoted by the strong correlation coefficient (p < 0.01) between the difference in the yield (CF-DI) and the difference in the number of spikelets/m2 and sink capacity between CF and DI. The lowland varieties produced comparable yields under DI and CF except Mitsu, Aki, and Hime; however, the average grain yields of upland varieties increased by 54% and 57% under DI compared with those under CF in 2019 and 2020, respectively. The number of fertile secondary spikelets decreased by 22% in DI due to the reduction in photosynthetic efficiency of the flag leaves at the grain filling stage. The DI increased the number of primary branches, primary spikelets, and fertile spikelets on the primary branches. However, to further promote the yield of rice varieties under DI, the extension of grain filling period, increased harvest index, sink strength of the secondary branches, and increased CO2 assimilation rate during the grain filling period are necessary. Also, the multipurpose varieties (Hoku and Beko) could be cultivated under DI in regions experiencing water scarcity.