【作者】 韩雪；

【导师】 林而达；

【作者基本信息】 中国农业科学院 ， 作物气象学， 2012， 博士

【摘要】 由于化石燃料的燃烧及土地利用的变化，全球大气CO₂浓度日益增加，预计到2050年，大气CO₂浓度将升高到550μmol·mol^-1。小麦是全球重要的粮食作物。本文利用中国北京豆麦轮作FACE，以强筋冬小麦CA0493和中麦175为供试材料，CO₂浓度处理设对照CO₂浓度(AmbientCO₂，415±16μmol·mol^-1)和高CO₂浓度(Elevated CO₂，550±17μmol·mol^-1)两个水平；施N处理设常规施氮(NN，底肥含N118kg·hm^-2+追肥含N70kg·hm^-2)和低氮(LN，底肥含N66kg·hm^-2+追肥含N17kg·hm^-2)两个水平。三次重复。于2007^-2010年连续试验，以CO₂浓度升高对冬小麦产量的影响为核心，进一步从光合碳吸收、物质积累和分配、氮素吸收和利用以及灌浆进程几方面深入研究，得出以下主要结论：⑴CO₂浓度升高使冬小麦产量三年平均增加10.71%，其中低氮肥和常规氮肥下增幅分别为10%和12%。主要增加了单位面积穗数（+6.16%）和穗粒数（+4.08%），减少了不孕小穗数(^-21.68%)。⑵CO₂浓度升高使冬小麦花前净光合速率和CO₂日同化量分别增加23.51%和11.91%，从而增加了花前干物质积累，但缩短了花后籽粒生长持续时间。光合碳吸收的促进作用到开花后逐渐减弱。这可能是由于开花后，CO₂浓度升高使籽粒对碳氮的需求增加，促使叶片中氮素向籽粒转移，从而使叶片叶绿素含量下降，出现光合适应。⑶CO₂浓度升高使冬小麦地上部生物量在拔节期、开花期和成熟期显著增加10.25%、17.65%和10.88%。明确了CO₂浓度升高对常规施肥干物质积累明显，特别是茎秆物质贮存增加。CO₂浓度升高使经济系数在低氮肥条件下增加0.97%，在常规氮肥条件下降低5.48%。⑷CO₂浓度升高使冬小麦植株氮积累量在拔节期、开花期和成熟期分别增加5.63%、12.34%和6.12%，氮素物质生产效率和籽粒氮素生产效率分别增加3.56%和3.90%。表明在CO₂浓度升高条件下，冬小麦对氮素的需求增加。为了达到供需平衡，提出未来550μmol mol^-1CO₂浓度条件下的推荐施N量为145kg hm^-2。根据植物需求控制氮肥用量，提高氮肥利用效率，减少氮肥损失，实现环境友好与增产双赢。在高CO₂浓度条件下，冬小麦产量与开花后植株吸氮量显著正相关，可以调控追肥时间，满足小麦开花后的氮素需求，进一步达到稳产增产的目的。CO₂浓度升高使植株含N量在拔节期、开花期和成熟期分别降低3.55%、4.73%和2.94%。CO₂浓度升高，地上部生物量的增幅高于氮吸收量的增幅，这可能稀释植株含N量，是植株含N量在高CO₂浓度下降低的部分原因。另一方面，CO₂浓度升高使小麦旗叶硝酸还原酶活性在两个生育期平均降低22.24%。这说明CO₂浓度升高抑制了NO3ˉ的还原，降低了小麦旗叶的含N量。⑸在高CO₂浓度条件下，中麦175的籽粒灌浆速率增加，而CA0493的籽粒灌浆速率降低。中麦175的旗叶光合功能期比CA0493长，有助于积累更多光合产物，促进灌浆速率。中麦175的单穗粒重比CA0493高45.26%。从源汇平衡角度来看，在高CO₂浓度条件下，中麦175的源端同化物供应能力和库容形成能力均优于CA0493，因而中麦175在高CO₂浓度条件下更加稳产高产。更多还原

【Abstract】 Fossil fuel combustion and deforestation have resulted in a rapid increase in atmospheric carbon dioxideconcentration （[CO₂]） since the1950’s. It is predicted that atmospheric CO₂concentration will reachabout550mol mol–1in2050. Globally, wheat is a major staple crop. Field experiments were based onthe soybean and wheat rotation Free Air CO₂Enrichment system at Beijing, China, two high glutencultivars of winter wheat （Triticum aestivum L. cv CA0493and Zhongmai175） were test for threegrowing seasons from2007to2010. Wheat was grown to maturity under elevatedCO₂(550±17μmol·mol^-1) and ambient CO₂(415±16μmol·mol^-1) rings, with normal nitrogen supply (NN,basal dressing before sowing118kg N·hm^-2+side dressing at jointing stage70kg N·hm^-2)and lownitrogen supply(LN，basal dressing before sowing66kg N·hm^-2+side dressing at jointing stage17kgN·hm^-2). Each treatment had three replicates. This study focus on the yield response of winter wheat toelevated CO₂, and get more detailed understanding of crop processes under high CO₂, such asphotosynthetic carbon assimilation, biomass production and distribution among wheat tissues, nitrogenuptake and utilization, grain filling rate and duration. Some main findings are listed as follows:⑴Elevated CO₂increased grain yield by10.71%across the three years. CO₂-induced yieldenhancement under low nitrogen and normal nitrogen supply were10%and12%, respectively. Theyield enhancement under elevated CO₂attributed to the increase of square meter panicle number （6.16%）and grain number per panicle （4.08%），and the reduction of infertile spikelet (^-21.68%).⑵Elevated CO₂increased the photosynthetic rate and daily integrated carbon assimilation by23.51%and11.91%under elevated CO₂before flowering, thus increase the dry matter accumulation beforeflowering, but shorten the grain filling duration after flowering. The carbon assimilation of CO₂-inducedenhancement reduced gradually after flowering. It might due to the imbalance of carbon and nitrogenbetween source and sink at high CO₂. Wheat plants under elevated CO₂required more carbon andnitrogen after anthesis than ambient CO₂, which may increase the nitrogen transfer from flag leaf.Therefore, leaf chlorophyll concentration and Rubisco content decreased under elevated CO₂,photosynthetic acclimation occurs.⑶Elevated CO₂increased the aboveground biomass at jointing, flowering and ripening stage across thethree years by10.25%,17.65%and10.88%, respectively. The study revealed that CO₂-inducedaboveground biomass enhancement was higher at normal nitrogen than low nitrogen, especially on thestem biomass accumulation. Elevated CO₂increased the harvest index by0.97%under low nitrogeninput, but decreased by5.48%under normal nitrogen input.⑷Elevated CO₂increased the nitrogen accumulation by5.63%,12.34%and6.12%under elevated CO₂at jointing, flowering and ripening stage across three years, respectively. Elevated CO₂increased theaboveground biomass per nitrogen uptake on an area basis and grain yield per nitrogen uptake on anarea basis at ripening stage by3.56%and3.90%. It indicated that winter wheat had larger nitrogen demand under elevated CO₂than ambient CO₂. To establish the new balance of nitrogen demand andsupply, this study estimated the recommended N application as145kg N hm^-2at550μmol mol^-1[CO₂]in the future. Fertilizer application could be adjusted based on the plant N demand. This strategy couldimprove the nitrogen recovery and reduce nitrogen loss in the soil, thus environment and grain yieldachieve a win-win objective. Grain yield and N uptake after flowering had a significant positivecorrelation at high CO₂, which indicated that regulate on the sidedressing date at jointing stage, couldbecome an effective way to increase the nitrogen uptake after flowering to improve the grain yield.Elevated CO₂decreased plant nitrogen concentration at jointing, flowering and ripening stage by3.55%,4.73%and2.94%across the three years, respectively. The enhancement of aboveground biomass wasmore than nitrogen accumulation under elevated CO₂, which may dilute the nitrogen concentration inplant tissues. On the other hand, elevated CO₂decreased the activity of nitrate reductase of flag leaf by22.24%across the flowering stage and milk stage. It indicated that elevated CO₂inhibited NO₃ˉassimilation, which caused the reduction of N concentration under elevated CO₂.⑸Elevated CO₂promote the grain filling rate of ZM175, but decreased grain filling rate of CA0493.The flag leaf of ZM175had longer photosynthesis function duration than CA0493, which wasbeneficial to accumulation more photoassimilation and transfer from leaf to grain to improve grainfilling rate for ZM175. Individual panicle grain weight for ZM175was45.26%higher than CA0493.From the source-sink balance point of view, the ability of photoassimilation supply from source andestablishment of new carbon sink for ZM175was comparatively favourable with CA0493underelevated CO₂. Therefore, ZM175was a stable and high-yield cultivar at high CO₂.更多还原