施硅对增温稻田CH4和N2O排放的影响

夜间增温幅度大于白天是气候变暖的显著特征。夜间增温影响水稻生产及CH4和N2O排放。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CH4和N2O排放影响已有报道,但二者耦合如何影响水稻生产及稻田CH4和N2O排放,尚不清楚。通过田间模拟试验,研究了夜间增温下施硅对水稻生长、产量及温室气体持续增温/冷却潜势和排放强度的影响。采用铝箔反光膜夜间(19:00-6:00)覆盖水稻冠层进行模拟夜间增温试验。增温设2水平,即常温对照(CK)和夜间增温(NW)；施硅量设2水平,即Si0(不施硅)和Si1(钢渣硅肥,200 kgSiO2/ha)。结果表明,施硅可缓解夜间增温对水稻根系活力的抑制作用,降低夜间增温对水稻地上部、地下部干重和产量的抑制作用。夜间增温显著提高CH4累计排放量,而施硅显著降低CH4累计排放量。夜间增温下施硅处理稻田CH4累计排放量在分蘖期、拔节期、抽穗-扬花期和灌浆成熟期比未施硅处理分别低48.12%、49.16%、61.59%和39.13%。夜间增温或施硅均促进稻田N2O排放,夜间增温下施硅在上述生育期以及全生育期的累计排放量依次比对照高78.17%、51.45%、52.01%、26.14%和40.70%。研究认为,施硅可缓解夜间增温对稻田综合增温潜势和排放强度的促进作用。

Effects of silicate supply on the emissions of methane and nitrous oxide in paddy field under nighttime warming

Asymmetric diurnal warming is one of the main features of global climate warming. Nighttime warming clearly impacts rice productions as well as methane (CH₄) and nitrous oxide (N₂O) emissions in paddy field. Silicon is beneficial element for crop growth. Silicate supply obviously increased yield, simultaneously decreased CH₄ emission in paddy field. Some reports have been available concerning nighttime warming or silicate supply effects on CH₄ and N₂O emissions in rice fields, but it is still unclear regarding the effects of both coupling on the emissions in paddy field. Field simulation experiment was conducted to investigate the effects of silicate supply on rice growth, yield and CH₄ and N₂O global warming potentials and emission intensity under nighttime warming. An aluminum foil reflective film was used to cover rice canopy at night (19:00-6:00) for nighttime warming excluding strong windy and rainy days under field conditions. The experiment was designed with two nighttime warming levels, i.e. nighttime warming (NW) and control (CK, ambient temperature), and two silicate supply levels, i.e. control (Si0) and Si1 (slag fertilizer, 200 kgSiO₂/hm²). The results showed that silicate application could alleviate the inhibitory effect of nighttime warming on root activity, the dry weight of aboveground and belowground as well as yield in rice. Nighttime warming significantly increased CH₄ cumulative emission, in contrast, silicate application significantly reduced CH₄ cumulative emission. The CH₄ cumulative emission in the treatment with silicate application under nighttime warming was 48.12%, 49.16%, 61.59% and 39.13% lower than that without silicate application at tillering stage, jointing stage, heading-flowering stage, and filling stage. Night warming or silicate application could promote N₂O emission in the field. Under nighttime warming, N₂O cumulative emission in the treatment with silicate application at the above-mentioned growth stages and the whole growth period was 78.17%, 51.45%, 52.01%, 26.14%, and 40.70% higher than that in the control (without silicate application). This findings suggest that silicate application was helpful in alleviating the stimulative effects of nighttime warming on the warming potential and emission intensity in the paddy field.