深水免耕移栽稻草覆盖栽培模式对晚稻温室气体排放及产量的影响

Effects of deep water irrigation with no-tillage and straw mulching on greenhouse gases emissions and yield of late rice

为了全面评价南方双季稻“早水晚用”节水栽培模式的意义，通过大田小区试验研究了晚稻移栽期灌深水＋免耕移栽＋稻草覆盖节水栽培模式对产量与温室气体排放的影响。结果表明：与常规栽培相比，在水稻齐穗期，节水栽培模式提高了9.6%～15.2%的光合速率（P〈0.01），但单叶水分利用率降低了13.3%～17.4%（P〈0.01）；节水栽培模式降低了每穗总粒数和结实率，导致减产显著（P〈0.05）；灌水深20 cm的甲烷排放量较对照减排了6.1%，而灌水深15和10 cm分别增排了6.5%和4.0%，同时灌水深20和15 cm节水模式较对照增排了N2O；灌水深20 cm节水模式的增温潜势和单位产量CO2排放当量均低于常规灌溉。因此，在南方稻区晚稻生产采用“移栽期蓄水深20 cm＋免耕移栽＋稻草覆盖节”节水栽培模式可以确保晚稻种植，同时减排温室气体，具有良好的经济生态效益。

In order to comprehensively evaluate ecological significance of the watersaving cultivation mode “reserving water in early rice to use for late rice” in double cropping rice of southern China, a field experiment was conducted to explore the combined effects of deep water irrigation in rice translating stage with notillage and rice straw mulching on yield and greenhouse gases emissions. The results showed that, compared with the convention cultivation （CK）, the photosynthetic rates of watersaving cultivation mode were increased by 9.6%-15.2% at the heading stage of rice （P〈0.01）, whereas the water use efficiency of single leaf was decreased by 13.3%-17.4% （P〈0.01）. Also, the watersaving cultivation model reduced the number of spikelets in single panicle and the setting rate, subsequently decreasing the rice yield significantly （P〈0.05）. Compared with CK, CH4 emission in the 20cmwaterlayer irrigation treatment was reduced by 6.1%, but was increased by 6.5% and 4.0% in the 15 and 10cmwaterlayer irrigation treatments, respectively. Meanwhile, the N2O emissions in the 20 and 15cmwaterlayer irrigation treatments were increased. On the whole, the global warming potential （GWP） and CO2 equivalent emissions per unit of yield in the 20cmwaterlayer irrigation treatment were lower than that of CK. In conclusion, watersaving cultivation model of 20cmwaterlayer irrigation in the transplanting stage with no-tillage and straw mulching can ensure the success of late rice transplanting, reduce greenhouse gas emissions and improve economic and ecological benefits of rice farming.