Grain yield, water-use efficiency, and physiological characteristics of rice cultivars under drip irrigation with plastic-film-mulch

摘要

The increased competition for water resources has intensified search for the most efficient water-saving techniques and water-use efficient cultivars. A 2-year field experiment was conducted to determine grain yield, grain quality, andwater-use efficiency (WUE) in rice (Oryza sativa L.) under drip irrigation with plastic-film-mulch. Koshihikari (a lowland Japónica cultivar), Norin 24 (an upland Japónica cultivar), and Princessari (a lowland cultivar, a derivative from Indica and Japónica crosses)were used in 2017, whereas only Koshihikari and Norin 24 were used in 2018. The experiments were carried out with two rice cultivation systems in both years: continuous flooding (CF) and drip irrigation with plastic-film-mulch (DPD). There was no significant difference in the grain yield of Koshihikari and Norin 24 under both CF and DPD. This was attributable to their comparable photosynthesis-associated parameters at the grainfilling stage. The high yield obtained under DPD was attributed to the increase in the number of spikelets per panicle. However, the decreased SPAD value of leaves and maximum quantum yield of photosystem II in Princessari were associated with the deficiency of available soil Fe and mild water stress, which reduced grain yield by54% under DPD compared with CF. The DPD increased WUE of Koshihikari and Norin 24 by 50% and 70%, respectively, and improved nutritional quality but increased the chalky grain percentage. The study demonstrated that, in cultivars adapted to Fe deficiency in the soil and mild water stress, DPD could significantly increase WUE while maintaining grain yield that is comparable to that under CF. Our results suggested that the DPD could be a promising rice-cultivation system in areas with limited water-resources.