| It is important to select the appropriate water saving irrigation technology to improve the rice yield and water use efficiency in our country. This study investigated the effects of different irrigation regimes on rice yield formation to come up with the suitable water saving irrigation technology for the paddy field in the middle reaches of Yangtze River, thus providing a theoretical basis for the further understanding of water saving potential and approaches as well as technical support for water use efficiency and rice production improvement in this area.Four types of irrigation regimes were established in this experiment:(1) continuous flooding (CF), (2) flooded and wet intermittent irrigation (FWI), (3) flooded and dry intermittent irrigation (FDI), and (4) supplementary irrigation (SI) to explore the effects of water waving irrigation on rice yield and water use efficiency. A water-saving drought-resistant rice variety (Hanyou3, HY3) and a local hybrid variety (Fengyuanyou299, FYY299) were planted under different water regimes in Wuxue City of Hubei Province in 2013 and 2014. Then based on the previous two-year field trial, the water-saving irrigation technology suitable for the middle region of Yangtze River was proposed, which is referred to as controlled irrigation with a bed-furrow base (BCI). Hereafter, with Hanyou113 (HY113) and Liangyou302 (LY302) as experimental materials and continuous flooding as control, the effects of BCI technology were tested by the field trial conducted in Jingmen City of Hubei Province. The results are as follows:(1) The meteorological conditions in 2014 were quite different from that in 2013. There was scarce rainfall in 2013, especially the continuous high temperature and drought during July and August, while the precipitation was abundant in 2014. The precipitation during rice growing season in 2013 was 39.1% lower compared with that during the same period in 2014. The two varieties responded differently to different water regimes under different climatic condition.(2) Compared with CF treatment, the effects of water-saving irrigation on dry matter accumulation and crop growth rate of two varieties before full heading were not significant in 2013. However, SI treatment significantly inhibited crop growth rate and dry matter accumulation of Hanyou3 after heading, and both AWD2 and SI treatments significantly inhibited dry matter accumulation of FYY299. Compared with CF treatment, AWD2 and SI treatments both significantly affected dry matter accumulation of two varieties before full heading stage. But crop growth rate of two varieties increased significantly after heading, resulting in no significant difference of the final dry matter accumulation compared with CF in 2014.(3) Compared with CF treatment, the leaf area index of HY3 under water-saving irrigation was similar at different growth stages. But the leaf area index of FYY299 was lower than that of CF treatment in 2013. Under AWD2 and SI treatments, leaf area index of two varieties significantly decreased at jointing, full heading and maturity stage in 2014.(4) Compared with CF treatment, the net photosynthetic rate of HY3 at full heading stage under AWD2 and SI treatments significantly increased, while the photosynthetic characteristics of FYY299 were no influenced in 2013. Compared with CF treatment, the net photosynthetic rate of FYY299 at full heading stage under AWD2 and SI treatments significantly increased, while that of HY3 maintained the same in 2014.(5) Due to seasonal drought in 2013, the grain yield of FYY299 under AWD2 treatment significantly decreased by 16% compared with CF treatment, mainly as a result of the significant decline of spikelets per panicle. Spikelets per panicle, filled grains per panicle, grain filling and 1000-grain weight in SI treatment significantly decreased, which caused the yields decrease byl7.8%(HY3) and 34.9%(FYY299). The yield and yield components of HY3 under AWD1 and AWD2 treatments were not affected in 2013. The water-saving irrigation treatments had no significant impacts on the yield and yield components of those two varieties in 2014.(6) Different yearly climatic types led to significantly different irrigation water input under different water regimes. Compared with CF treatment, the water input of water-saving irrigation treatments was 37% to 82% lower during 2013 and 2014. Compared with CF treatment, the TWUE of HY3 respectively increased by 41.5% and 32.1% under AWD1 and AWD2, while that of FYY299 only increased by 17.9% and 17.9% in 2013. The TWUE of two varieties under water-saving irrigation treatments significantly were 94.9% to 123% higher than that of CF, and meanwhile the yield was stabilized in 2014.(7) The controlled irrigation technology with a bed-furrow base (BCI) was established based on the climatic conditions in the middle reaches of Yangtze River, and its effects were investigated. Compared with CF treatment, the dry matter accumulation, leaf area index, tiller dynamics, chlorophyll content, yield and yield components of two varieties under BCI treatment were not significantly different, but the TWUE significantly increased by 38.1%(HY113) and 43.1%(LY302).Our results suggest that the appropriate water-saving irrigation technology has a high potential in saving water in the midstream regions of Yangtze River with high groundwater table, and selecting varieties adapted to different climatic types may increase water use efficiency. Controlled irrigation technology with a bed-furrow base has advantages in maintaining rice yield, and higher water-saving. However, it remains to be further studied regarding the applicability of BCI in rice production in the midstream regions of Yangtze River. |
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