水稻高产新品种利于稻田甲烷减排

近日,中国农业科学院作物科学研究所张卫建研究员领衔的作物耕作与生态创新团队,在水稻植株对稻田温室气体排放的调控效应及机制研究中取得重要进展,阐明了水稻新品种在典型稻田的甲烷(CH4)减排效应,揭示了水稻植株与稻田甲烷排放的地上地下互作机制。此研究说明我国现代水稻育种是一个既增产又减排的历程,对应对气候变化的作物品种改良和稻作技术创新具有重要意义。相关论文于2017年5月2日在线发表在Global Change Biology上。

我国是世界上最大的水稻生产和消费国,稻田甲烷排放问题一直受到国际广泛关注。在水稻复种指数持续下降、稻田面积难以增加、收获指数已近高限等多重压力下,通过品种改良和农艺创新,实现水稻单产的持续稳定增长,是确保我国“口粮绝对安全”的根本途径。适度提高植株生物量和增强茎秆及根系,是突破水稻单产徘徊不前的育种与栽培新途径。由于水稻当季光合产物也是稻田甲烷产生菌的重要碳源,因此,国内外普遍认为水稻高产新品种将进一步增加稻田甲烷排放。

该团队研究发现,水稻高产新品种不仅可以通过根系分泌物和凋落物的形式为稻田甲烷产生菌提供更多的碳源,促进甲烷产生过程;同时也可以通过强大的通气组织(根系)为稻田甲烷氧化菌提供更多的氧气,促进甲烷氧化过程。当土壤贫瘠时,甲烷产生的碳源主要来自当季光合产物,高产品种可以显著提高甲烷产生进而增加排放。当土壤比较肥沃时,土壤有机碳源充足,但氧气不足,高产品种根际泌氧强,可以促进甲烷氧化进而减少排放。可见,水稻品种对稻田甲烷排放的调控,是通过植株影响土壤碳源和氧源及微生物群落状况,是一个地上地下的互作过程。

研究表明,高产新品种对稻田甲烷排放的影响取决于稻田土壤有机质水平。当稻田土壤贫瘠(有机质含量低于1.4%)时,高产品种会提高甲烷排放;在中高产稻田(有机质含量高于2.1%),高产新品种显著降低稻田甲烷排放。由于中高产稻田的甲烷排放总量远高于贫瘠稻田,因此,高产新品种的甲烷净减排量远高于其在贫瘠稻田的增排效果。根据第二次土壤普查数据,我国80%以上的稻田有机质含量高于2.1%,且近年来呈现递增趋势。由此可见,我国水稻高产新品种的大面积推广,不仅保障了国家的口粮安全,而且起到了甲烷显著减排效果。

该研究得到了“十三五”国家重点研发计划、中国农科院科技创新工程和“国家留学基金”等项目资助。作科所与南京农业大学联合培养的博士研究生江瑜为文章第一作者,张卫建研究员为通讯作者。(来源:中国科学报 张晴丹)

Higher yields and lower methane emissions with new rice cultivars

Abstract Breeding high-yielding rice cultivars through increasing biomass is a key strategy to meet rising global food demands. Yet, increasing rice growth can stimulate methane (CH4) emissions, exacerbating global climate change, as rice cultivation is a major source of this powerful greenhouse gas. Here, we show in a series of experiments that high-yielding rice cultivars actually reduce CH4 emissions from typical paddy soils. Averaged across 33 rice cultivars, a biomass increase of 10% resulted in a 10.3% decrease in CH4 emissions in a soil with a high carbon (C) content. Compared to a low-yielding cultivar, a high-yielding cultivar significantly increased root porosity and the abundance of methane-consuming microorganisms, suggesting that the larger and more porous root systems of high-yielding cultivars facilitated CH4 oxidation by promoting O2 transport to soils. Our results were further supported by a meta-analysis, showing that high-yielding rice cultivars strongly decrease CH4 emissions from paddy soils with high organic C contents. Based on our results, increasing rice biomass by 10% could reduce annual CH4 emissions from Chinese rice agriculture by 7.1%. Our findings suggest that modern rice breeding strategies for high-yielding cultivars can substantially mitigate paddy CH4 emission in China and other rice growing regions.

原文链接:http://onlinelibrary.wiley.com/doi/10.1111/gcb.13737/pdf

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