施硅调控增温稻-麦土壤CH4和N2O排放及其作用机制

Asymmetric diurnal warming is one of the main features of global climate warming. Nighttime warming clearly impacts rice and winter wheat productions as well as methane (CH4) and nitrous oxide (N2O) emissions in the fields. Silicon is beneficial element for crop growth. Silicate supply obviously increased yield, simultaneously decreased CH4 emission in paddy field. Reports have been available concerning nighttime warming or silicate suppy effects on CH4 and N2O emissions in rice or wheat fields, but it is still unclear regarding the effects of both coupling on the emissions in rice-wheat rotation system. In this proposal, pot, field and culture experiments will be conducted in the typical rice-winter wheat rotation system of Yangtze River Delta region. The purposes of this study will be to mainly investigate the effects of different silicate fertilizer types and fertilization amounts on CH4 and N2O production and emissions ; the types and amounts effects on physical and chemical properties of the rotated soil; the effects on the content and composition of root exudates as well as the key functional microbial communtiy composition, abundance and diversity; as well as the effects on plant growth, physiological properties and yield in the rotation system under nighttime warming. This study will be helpful in revealing silicate supply effects on CH4 and N2O emissions and its mechanism under nighttime warming, accurately estimating regional emissions in the rotated soils under climate warming, developing new emission reduction techniques, and promoting the ability of rice and winter wheat productions to deal with and adapt to climate change.

夜间增温幅度大于白天是气候变暖的显著特征。夜间增温对稻麦生产及农田甲烷（CH4）和氧化亚氮（N2O）排放有重要影响。硅是作物有益元素，施硅可提高产量，减少稻田CH4排放。增温或施硅单因子对稻田或麦田CH4和N2O排放影响已有报道，但二者耦合影响稻麦轮作土壤（稻-麦土壤）CH4和N2O排放及其作用机制，尚不清楚。本项目拟通过盆栽、田间和培养试验，以长三角典型稻麦轮作系统为研究对象，重点研究不同硅肥种类和施用量对增温稻-麦土壤CH4和N2O产生排放的影响；对增温稻-麦土壤理化性质的影响；对根分泌物组成和含量及相关土壤微生物群落的影响；以及对夜间增温下稻麦植株生长、生理和产量影响，揭示施硅调控增温稻-麦土壤CH4和N2O排放及其作用机制，为气候变暖背景下区域稻-麦土壤CH4和N2O排放量精确估算、研发减排新技术，通过施肥提高稻麦生产应对和适应气候变化的能力等方面提供试验依据。

夜间增温幅度大于白天是气候变暖的显著特征。夜间增温对稻麦生产及农田CH4和N2O排放有重要影响。施硅可提高产量，减少稻田CH4排放。增温或施硅对稻田或麦田CH4和N2O排放影响已有报道，但二者耦合影响稻麦轮作土壤（稻-麦土壤）CH4和N2O排放及其作用机制，尚不清楚。通过田间、盆栽和培养试验，主要研究了不同硅肥种类和施用量对增温稻-麦土壤CH4和N2O产生排放的影响及其作用机制。结果表明，夜间增温降低水稻地上部干重、全株干重及产量，施硅显著提高水稻地上部干重、全株干重并增加产量。夜间增温和施硅均提高小麦地上部干重和产量，夜间增温下施硅使小麦地上部干重和产量分别比对照提高33.13%和7.54%。夜间增温降低水稻糙米率、精米率和淀粉含量，施硅显著提高水稻糙米率、精米率、整精米率以及直链淀粉和总淀粉含量。夜间增温或施硅均显著降低小麦直链淀粉含量，显著提高其支链淀粉含量。夜间增温显著促进稻田CH4排放，施硅显著降低稻田CH4排放，夜间增温下施硅使稻田CH4累计排放比未施硅的低46.67%。夜间增温或施硅均显著促进稻田N2O排放，夜间增温下施硅使稻田N2O累计排放比对照高40.70%。夜间增温或施硅均可显著促进麦田土壤CH4累计吸收，夜间增温下施硅使麦田土壤CH4累计吸收比对照高33.39%；夜间增温可使麦田N2O累计排放比对照显著提高38.38%；夜间增温下施硅使麦田N2O累计排放比未施硅显著降低10.52%。夜间增温下施硅稻麦农田综合增温潜势（SGWP）和排放强度（GHGI）分别比未施硅显著降低32.63%和35.90%，施硅有效缓解夜间增温对稻麦系统综合增温潜势和排放强度的促进作用。夜间增温土壤亚硝酸型厌氧甲烷氧化潜力显著高于对照处理，而施硅处理则显著低于对照处理。夜间增温处理的土壤厌氧甲烷氧潜力最高，而施硅处理潜力最低。本研究揭示硅在稻田甲烷减排中的重要作用，揭示了夜间增温可显著促进稻田甲烷排放。本研究对促进钢铁工业废弃物资源化利用，农田固碳减排，通过施肥提高稻麦生产应对和适应气候变化的能力等方面有重要理论和实际意义。