FACE增温条件下北方稻田稗草与水稻竞争关系及其机理研究

The atmospheric CO2 concentration has reached to 400 umol/mol currently from 280 umol/mol before the Industral Revolution(1750), and the temperature also increased more than 0.84℃. accordingdly, both CO2 concentration and temperature will be increased continuely in the coming days. As one of the substrates for plant photosynthesis, CO2 concentration increasing had and will be affected profoundly plants physiology, metabolism and population competition. The barnyardgrass(C4) is the dominant weed for rice in North China. Under the impacts of climate warming and planting patterns change in recent years, the barnyardgrass is becoming more and more serious in paddy field in North China, which weaken rice growth and development, destroied rice yield and quality, by plundering light, radiation and soil fertilizer with rice. In the reseach project proposal, a four-year field experiment, in which different ratio of barnyardgrass and rice,treated with CO2 enrichment and temperature increasing, would be desiged, is planning to be conducted in Changping Agricultural Experiment Station, by using of the FACE system (CAAS FACE) in North China. The physiological factors and metabolism features, and soil fertilizer absorb characteristic of barnyardgrass and rice would be observed parallelly, a series of experimental data about response of barnyardgrass to CO2 enrichment under FACE system with tempreture increasing would be collected. The different responses between barnyardgrass and rice to CO2 enrichment and temperature increasing, and their competition relationship would be compared and analyzed. As a result, the impact mechanism of CO2 enrichment and temperature increasing on barnyardgrass under FACE system, and the competition relationship between barnyardgrass and rice would be explained and delivered. The outcomes of the research will promote understanding on the impacts of CO2 enrichment and climate warming on crop population development.

大气中二氧化碳（CO2）浓度已由工业革命前约280umol/mol增加到目前约400umol/mol，平均温度升高了0.84℃，未来二者仍将同步持续增高。在光热条件变化背景下，近年来北方稻田最优势杂草稗草发生严重，通过掠夺光热资源和土壤养分，严重弱化了水稻长势，影响水稻的产量和品质。本项目拟采用FACE平台，将稻田稗草和水稻按不同种植比例开展CO2浓度与温度增高的模拟试验，观测稗草和水稻生理代谢与养分吸收能力的变化，获得稻田稗草对CO2浓度与温度增高响应的试验数据，进行FACE增温条件下稗草生理响应以及稗草和水稻竞争关系比较研究，阐明CO2浓度增高对稻田稗草生长发育以及稗草与水稻竞争关系影响的机理，提高气候变化对作物生长发育影响的认知。

大气中二氧化碳（CO2）浓度已由工业革命前约280umol/mol增加到2020年的410umol/mol，增幅达46.5%。尽管国际社会在努力寻求控制CO2排放的有效途径，但短期内大气中CO2浓度继续增高的趋势难以改变，对陆地生态系统的影响仍将持续并强化。在光热条件变化背景下，近年来北方稻田最优势杂草稗草发生严重，通过掠夺光热资源和土壤养分，严重弱化了水稻长势，影响水稻的产量和品质。本项目采用开放式CO2富集系统（Free-air CO2 Enrichment，FACE），开展了CO2浓度增高对稻田稗草生长发育及稻田稗草与水稻竞争力影响的模拟试验。结果表明，稗草与水稻混种使水稻结实率显著降低，水稻千粒重显著增加，最终使水稻产量显著降低；CO2浓度升高使水稻干物质量显著提高，稗草使水稻干物质量显著降低；而CO2浓度升高和稗草互作对水稻干物质影响不显著。CO2浓度升高使水稻剑叶净光合速率、胞间CO2浓度及SPAD值显著升高，使水稻剑叶气孔导度和蒸腾速率显著降低，稗草显著降低了水稻剑叶净光合速率、胞间CO2浓度、气孔导度、蒸腾速率、瞬时水分利用效率及SPAD值。水稻抽穗后CO2浓度升高对水稻光合作用的影响大于稗草对水稻光合作用的影响。稗草混种处理对水稻每穴穗数和结实率均有负向作用，对水稻拔节期的株高有负向作用；使水稻分蘖期叶面积指数下降了23.2%，达到显著水平。稗草混种处理使水稻在抽穗期分蘖数减少了34.5%，达到显著水平；其他阶段分蘖数均未达到显著水平。稗草混种处理降低了水稻根系氧化力，在水稻分蘖期、 拔节期、 抽穗期分别降低了41.6%、10.9%、14.2%，且均达到显著水平。稗草混种处理对水稻根系总吸收面积有负向作用，且在抽穗期和成熟期达到显著水平，在分蘖期达到极显著水平。研究结果初步阐释了CO2浓度增高条件下稻田稗草竞争趋势及响应机理，提高了CO2浓度增高及气候变化对作物生长发育影响的认知。