UV-B增强下施硅对稻田不同源甲烷产生的影响机制研究

The elevated UV-B radiation induced by ozone depletion in stratosphere has been regarded as one of the important issues in global change research. Silicon is beneficial to high and sustainable production of rice and helps plants to overcome abiotic and biotic stresses. Silicon can increase rice resistance to UV-B radiation, but it is still unknown for silicon how to regulate methane (CH4) production in rice plant and paddy soil. In this proposal, pot and field experiments as well as incubation experiments will be performed to investigate the effects of silicon fertilization on CH4 production in rice plant and paddy soil in relation to rice growth, active oxygen metabolism and root exudation under eelvated UV-B radiation. UV-B radiation will be designed with two levels, i.e. ambient (control) and elevated by 20%. Silicon will be supplied with two types of silicate fertilizer, i.e. iron (Fe) slag silicate fertilizer and sodium metasilicate. The experiments will be performed at the Station of Agricultural Meteorology, Nanjing University of Information Science and Technology, Nanjing, China. Firstly, pot and field experiments will be conducted to investigate the effects of silicate fertilization (types and amounts) on methane production, oxidation and emission as well as methanogenic and methanotrophic diversities under elevated UV-B radiation. Secondly, incubation experiment will be carried out to collect root exudates with being filtered and concentrated for measuring dissolved organic C. With the method of resin separation, the collected root exudates will be separated into several groups to determine the composition of root exudates. Finally, pot and incubation experiments with sterilization will be performed to measure CH4 emission flux in rice plant. Plant samples will be simultaneously collected to determine the parameters related to the processes of growth, physiological and active oxygen metabolism. Through the aforementioned experiments, it will be helpful in elucidating the mechanisms responsible for CH4 production in rice plant and paddy soil as affected by silicon fertilization under elevated UV-B radiation. This research will be very important in theory and practice for elucidating the relative contribution of CH4 production in rice plant and paddy soil, accurately evaluating regional CH4 emission, developing new techniques for reducing CH4 emission by fertilizing silicon to rice and improving the content for assessing the ecological and environmental assessment in rice field under elevated UV-B radiation.

大气平流层臭氧耗损导致UV-B增强是全球变化研究的重要问题之一。水稻是喜硅作物，施硅可提高水稻抗UV-B辐射能力，但其如何影响甲烷产生尚未见报道。采用盆栽、田间和培养方法，研究UV-B增强下不同硅肥和施用量对水稻植株源和土壤源甲烷产生的影响及其与水稻生长、活性氧代谢和根系分泌的关系。首先，研究UV-B增强下不同硅肥和施用量对水稻甲烷产生、氧化和排放及甲烷微生物多样性的影响。其次，研究UV-B增强下施硅对水稻根分泌物数量和组成的影响。最后，研究UV-B增强下不同硅肥和施用量对水稻植株源甲烷产生及活性氧代谢的影响。通过上述试验揭示UV-B增强下施硅对不同源甲烷产生的影响及其机制。本研究有助于阐明水稻植株源和土壤源甲烷的相对贡献，对区域稻田甲烷排放量精确估算，结合水稻施硅研发甲烷减排新技术及完善UV-B增强下稻田环境评价的内容有重要理论和实践意义。

大气平流层臭氧耗损导致地表UV-B增强是全球变化研究的重要问题之一。水稻是喜硅作物，施硅可提高水稻抗UV-B辐射能力，但其如何影响甲烷产生尚未见报道。本项目采用盆栽模拟试验、田间模拟试验和培养模拟试验的方法，研究了UV-B增强下不同硅肥和施用量对植株源和土壤源甲烷产生的影响及其与水稻生长和活性氧代谢的关系。结果表明，施硅能缓解UV-B增强对水稻生长的抑制作用，使分蘖数、叶绿素含量、地上部和地下部生物量增加。施硅对水稻生长的促进作用，随施硅量（硅酸钠）的增加而增加，钢渣硅肥的促进作用大于硅酸钠。UV-B增强可提高稻田甲烷的排放通量和累积排放量，施硅显著降低甲烷的排放通量和累积排放量，且甲烷排放随施硅量的增加而减少。在施硅量相同的情况下，钢渣硅肥的减排效果优于硅酸钠。表明在水稻生产中，施用钢渣硅肥不仅能实现废弃物利用，而且可有效降低UV-B增强下稻田甲烷的排放量。本研究首次揭示了硅在水稻甲烷减排中的重要作用,揭示了UV-B增强可显著促进水稻甲烷排放。本研究对实现废弃物资源化利用、温室气体减排及环境保护，对促进区域农业生产及社会经济健康发展有重要理论和实际意义。