Effect Of Biodegradable Film Mulching On Growth And Methane Emission Of Mechanical Transplanted Rice(Oryza Sativa L.)

Rice is China's main food crop,and stable production and high yield are extremely important for ensuring food security.Rice film mulching cultivation can solve the problem of rice cultivation in water-scarce regions and low-temperature chilling injury regions.At that time,the film-mulching needed to be artificially laid,which increased the production cost,and the non-degradable mulch residue caused pollution to the environment,limiting the development and application of the film mulch cultivation.In order to conform to the current trend of light simplified and green rice production,the biodegradable film mulching machine planting has appeared.Currently,there are few studies on the biodegradable film-mulching machine planting and the impact of biodegradable film-mulching machine planting in different ecological regions on rice production is unclear.Thus,this study carried out the research on biodegradable film-mulching machine planting through the two ecological regions in the north and south.At the fuyang experimental base of China rice research institute and the liuhe planting base of tonghua city,jilin provincein 2018 and 2019.Using indica-japonica hybrid rice variety Yongyou538?Fuyang?and high-quality rice variety Wuyoudao 4?Liuhe?as materials.This paper mainly studies the influence of biodegradable film mulching on the growth and quality characteristics of transplanted rice,the release characteristics of greenhouse gases,as well as the changes of soil nutrition.Clarify the technical characteristics of rice biodegradable film mulch planting.With a view to providing a theoretical basis for green efficiency-increasing and quality-improving of rice and ecological cultivation.The main findings are as follows:1.Effect of biodegradable film mulching on growth and quality of mechanical transplanted rice.1)Both the northern and southern biodegradable-film mulched rice could promote the growth of rice leaves and increase the rate of leaf emergence.In the early growth stage,the rate of leaf emergence of the northern plastic-film mulched rice was 0.6?0.9 leaves faster than that of the control.Thus accelerated the process of rice growth,the maturing stage of film mulched rice was 7 days earlier in the north and 3 days earlier in the south.2)The mulching treatment can to increase soil temperature,the mulching treatment of northern single-season rice promoted the early growth and fast growth of rice tiller,and significantly increased the effective tillers number of per hm² by 357,000 compared to the control.For the south,early-season rice increased significantly per hm² by 226,000.3)The brown rice,milled rice and protein content were significantly improved by biodegradable film mulching in single-season rice of north,while the head rice was significantly increased in single-season rice of south with biodegradable film,and the head rice of early rice in south,but did not reach the significant level.4)The yield of mulched rice in the north and the south increased significantly.The yield of mulched single-season rice of north increased by 8.7%,early-season rice of south increased by 7.9%,and single-season rice of south increased by only 4.1%.To analyze its yield components,the single-season rice in the north and the early rice in the south mainly increase the yield by increasing effective panicle number,and the single-season rice in the south increases the yield by increasing spikelets per panicle.2.Effect of biodegradable film mulching on greenhouse gas emission of rice.1)Both south and north with biodegradable film significantly reduced CH₄ emissions in rice fields by 43.5%and 52.4%,respectively.The main reduction effect is that biodegradable film mulching treatment can significantly reduce the peak methane emission.To further analysis of the changes in the abundance of soil methanogens and methanotrophs related to CH₄ emissions showed that biodegradable film mulching treatment in both northern and southern ecologicalregions could significantly reduce the abundance of methanogens and improve the abundance of methanotrophs,and the change rule was basically consistent with CH₄ emissions.2)The effect on N₂O emission in the rice field was different between the north and the south,compared with the control,N₂O emission in the biodegradable film mulching treatment in the south was significantly reduced by 47.9%,while N₂O emission was slightly higher than that of the control in the north.On the whole,the biodegradable film mulching treatment significantly reduced the greenhouse gas warming potential in rice fields.It also significantly inhibited the greenhouse gas emission intensityof rice field,The decrease were 46.6%and 56%,respectively.3.Effect of biodegradable film mulching on soil nutrient and nitrogen use efficiency of rice.1)The biodegradable film mulching cultivation increases soil temperature,the effect of temperature increase in northern mulched rice was better,the warming effect is mainly concentrated in the early period of growth,especially in the period from transplanting to panicle initiation stage,the average daily temperature of soil increase was 2.76?.2)The biodegradable film mulching treatment can significantly increase soil organic matter,total nitrogen and alkali-hydrolyzed nitrogen content,and showed consistent results between different years and in different ecological regions.The soil organic matter,soil nitrogen and alkali hydrolyzed nitrogen content of southern biodegradable film mulching treatment increased significantly by 5.2%?6.3%,11.5%?18.3%,13.2%?69.8%.The soil organic matter,soil nitrogen and alkali hydrolyzed nitrogen content of biodegradable film mulching in the north increased significantly by 5.8%?27.1%,13.5%?27.4%,11.4%?69.4%.3)The biodegradable film mulching treatment can increase the dry matter accumulation and nitrogen accumulation at each growth stage,and the nitrogen accumulation at mature stage will increase by 2.5 and 5.8%in 2018 and 2019,respectively,and can significantly improve the nitrogen agronomic efficiency,nitrogen recovery efficiency,nitrogen partial productivity,nitrogen dry matter production efficiency.From a physiological point of view,biodegradable film mulching treatment can increase the activities of nitrate reductase,glutamine synthetase,and glutamate synthase in functional leaves,and the photosynthetic rate increased significantly by 6.5%at 10 days after the full heading stage.It is beneficial to maintain a good photosynthetic production capacity in later period.