再生稻种植对我国稻田CH4和N2O排放的影响

The ratoon rice is harvested one more time than the single rice, resulting in a very large increase of rice production. Right now, the area suitable for ratoon rice cultivation in China is around 50 million mu, which is able to increase rice grain yields up to 20 million ton per year. To meet the increasing demand of the population for food, the area is expected to expand continually under the conditions of global climate change in future, thus leaving the rice production increase potential further enlargement. As a result, developing ratoon rice is of great significance to adapt to global climate change and to ensure the national food security. It is supposed that planting ratoon rice is most likely to change the seasonal variations of CH4 and N2O emissions from the field, and probably to increase the total amounts of CH4 and N2O emissions. However, the related investigations are seriously insufficient so far. In addition, ratoon rice planting is mainly restricted by rice cultivar and cultivation technique but no observations were available about the effects on CH4 and N2O emissions. The project aims to elucidate the seasonal variations of CH4 and N2O emissions from ratoon rice fields in China and the corresponding total budgets, and to reveal the mechanisms of rice cultivar and cultivation technology affects the CH4 and N2O emissions from ratoon rice fields. The significances of the project are to pave a good way for further studying the effect of ratoon rice planting on CH4 and N2O emissions from rice fields in the conditions of future climate change, and to supply reference data for accurately estimating the amounts of CH4 and N2O emissions and clarifying the inventories of CH4 and N2O emissions from paddy fields in China.

再生稻较单季稻多收一季，存在巨大的增产潜力。我国目前适宜种植再生稻的面积约有5000万亩，可使稻谷每年增产达2000万吨。为满足日益增长的人口对粮食的需求，未来气候变化条件下，再生稻的种植面积有望继续增加，其增产潜能也将随之增大。因此，发展再生稻对适应全球气候变化和保障国家粮食安全具有重要意义。然而种植再生稻势必改变稻田CH4和N2O排放的季节变化规律，且很可能增加CH4和N2O的排放总量，但相关研究还严重缺乏。再生稻种植主要受水稻品种与栽培技术的限制，目前尚无它们对再生稻CH4和N2O排放影响的报道。探明我国再生稻稻田CH4和N2O排放的季节变化规律和排放总量、揭示水稻品种与栽培技术对再生稻稻田CH4和N2O排放的影响机制，能为未来气候变化下进一步研究再生稻种植对CH4和N2O排放的影响做好铺垫，又为准确评估我国稻田CH4和N2O排放总量、厘清我国稻田CH4和N2O排放清单提供参考数据。

再生稻种一茬可收获两次，对增加粮食产量和保障国家粮食安全有重大意义。本项目研究了覆膜再生稻田CH4和N2O排放的季节变化规律、栽培方式、水稻品种、氮肥品种及配比对再生稻田CH4和N2O排放的影响、估算了湖北、重庆再生稻田面积及CH4和N2O排放量。主要结果如下：.与覆膜单季稻相比，覆膜再生稻CH4和N2O排放峰提前出现，CH4和N2O排放量显著增加，其综合温室效应（GWP）增加17%。种植再生稻显著增加水稻产量17%，其温室气体排放强度（GHGI）与单季稻无明显差异。与中稻季相比，再生季分别减少CH4和N2O排放68–70%和62–89%。头季灌浆期较高的产甲烷菌丰度和再生季拔节期较高的甲烷氧化菌丰度可能是导致头季高CH4排放和再生季低CH4排放的原因。.从常年淹水转变为覆膜单季稻栽培，CH4排放和GHGI减少56%和51%，N2O排放和NEEB增加365%和884%。覆膜再生稻可进一步减少12%的GHGI、增加18%的NEEB，为缺水地区的环境和种植者带来双赢。尽管晶两优华占稻季GWP高达10.95 t CO2-eq ha–1，但其产量比其它品种显著高出8–16%，因此其GHGI最低，为1.10 t CO2-eq t–1 yield。控释肥处理增加了8–17%的N2O排放，4–7%的水稻产量，减少了3–6%的GHGI。施用控释肥且保持促芽肥发苗肥比例为12:10，可获得高产，降低GHGI。.基于卫星遥感技术获取湖北省再生稻面积12.84万公顷，主要分布在中南部和东部。利用面积扩展法估算湖北省和重庆市再生稻田CH4排放量分别为12.1×107 kg和4.77×107 kg、 N2O排放量分别为26.8×104 kg N和3.74×104 kg N。.研究结果可为进一步评估和预测未来气候变化条件下再生稻在我国大面积推广的可行性、以及厘清我国稻田CH4和N2O排放清单提供科学依据。