[Effects of increased planting density with reduced nitrogen fertilizer application on greenhouse gas emission in double-season rice fields under water saving and simple cultivation mode].

To clarify the effects of increased density and reduced nitrogen on greenhouse gas emission in double-season paddy fields under the water-saving and simple cultivation mode, we used Luliangyou 996 (early rice) and Fengyuanyou 299 (late rice) as materials to collect greenhouse gas by closed static box method, monitored the dynamics of CH and NO emissions from different combinations of increased density and reduced nitrogen for early and late rice, and explored changes in cumulative CH and NO emissions, global warming potential (GWP) and greenhouse gas intensity (GHGI) as affected by different combinations of increased density and reduced nitrogen from double-season rice fields. The results showed that the cumulative emissions of CH and NO from different combinations were significantly different. Compared with the control (CK), cumulative CH emission, GWP and GHGI in the two seasons decreased by 50.8%, 37.3%, and 42.9% for the combination of increased density and reduced nitrogen IR(the amount of nitrogen applied of early rice was 86.4 kg·hm, the density was 360000 holes·hm; the amount of nitrogen applied of late rice was 108 kg·hm, the density was 320000 holes·hm), respectively. IR of early rice had the lowest NO cumulative emission, being 33.7% lower than CK. IR(the amount of nitrogen applied of early rice was 103.2 kg·hm, the density was 320000 holes·hm; the amount of nitrogen applied of late rice was 129 kg·hm, the density was 280000 holes·hm) of late rice had the lowest NO cumulative emission, being decreased by 94.9%. IR had the lowest annual total GWP and GHGI of double-season paddy fields. Compared with other treatments of increased density and reduced nitrogen, the IR treatment, where nitrogen fertilizer in both early and late rice was reduced by 28.0%, the density of early rice was increased by 28.6%, and the density of late rice was increased by 33.3%, was an effective and safe option for simultaneously ensuring high yield and reducing greenhouse gas emissions.