北方冬麦区CO_2浓度增高与氮肥互作对冬小麦生理特性和产量的影响

【目的】阐明CO_2浓度增高与氮肥互作对冬小麦生理和产量的影响,为客观评估气候变化背景下冬小麦生产潜力提供理论依据。【方法】2011—2014年利用开放式CO_2富集系统(FACE)平台,采用盆栽方法,研究冬小麦"中麦175"在不同CO_2浓度及高低氮肥水平下(高浓度CO_2 550 mg·L~(-1)和大气浓度390 mg·L~(-1);高氮N1,0.16 g·kg~(-1)和低氮N0,0 g·kg~(-1))的生育进程、光合特征及产量变化。CO_2富集处理于每年返青-成熟期间进行,通气时间为每日6:30-18:30,夜间不通气。CO_2浓度通过计算机程序控制,并根据具体风向和风速控制释放管电磁阀的开合度,实现预定设置浓度。【结果】盆栽试验表明与大气CO_2浓度相比,高浓度CO_2加快了冬小麦生育进程,拔节期提前1d,开花期可提前1-2 d,全生育期可缩短3-5 d,高氮肥处理对生育进程具有延迟作用,开花期延长1-2 d,灌浆期可延长4-5 d,同步缓解高浓度CO_2对生育进程的加快作用;高浓度CO_2使叶片光合速率提高13.7%,产量平均提高16.0%,且在高氮肥下光合速率的增幅比低氮肥相对提高2.5%,蒸腾速率提高13.5%;试验中单独高氮较低氮的增产效果达到50%,高于单独高浓度CO_2较大气浓度的增产效果;高浓度CO_2对产量构成中穗粒数和千粒重提高明显,高浓度CO_2较大气浓度穗粒数增加3.69%,单独高氮处理较低氮处理平均穗粒数增加3.43%,即CO_2肥效起到了增加穗粒数的作用并略高于单独氮肥处理,高氮和高CO_2双重促进下的穗粒数最多,达到38.37粒/穗,低氮和低CO_2处理的穗粒数水平最低,可见CO_2和氮肥互作对穗粒数的促进相对更明显,各自单独施用的促进作用彼此差异不大,但低氮、大气CO_2浓度处理的穗粒数则相对较低;与大气CO_2浓度相比,高浓度CO_2的千粒重增加5.3%,高氮高浓度CO_2处理的千粒重大约提高7.3%,说明氮肥的施用促进了高浓度CO_2对千粒重的提升效果。【结论】高浓度CO_2可提高冬小麦产量,且与氮肥有明显的正向互作关系,高氮肥处理可降低CO_2浓度升高对生育期的加快作用,提高光合能力,促进CO_2肥效的发挥;CO_2对冬小麦产量的提高主要是缘于CO_2浓度升高有利于穗粒数和千粒重的增加,育种中可以做综合性考虑和应用。

Interactive Effects of Elevated CO2 and Nitrogen on the Physiology and Yield of Winter Wheat in North Winter Wheat Region of China

【Objective】This study aims to elucidate the interactive effects of elevated CO₂ concentration CO₂] and different nitrogen applications on phenology, photosynthesis and yield of winter wheat, then to provide theoretical understanding for objective assessment on the potential yield of winter wheat under climate change conditions.【Method】The experiment was conducted from 2011-2014 using a Free Air CO₂ Enrichment (FACE) facility with pot experiment and winter wheat cultivar “Zhongmai 175”. Each pot was filled with 45 kg of sieved soil. The treatments were set at elevated CO₂] of 550 mg·L^-1 and ambient CO₂] of 390 mg·L^-1，nitrogen fertilizer applied at N1, 0.16g·kg^-1 soil and N0, 0 g·kg^-1 soil. The changes of phenology, physiology and yield of winter wheat were investigated. The elevated CO₂ feeding was in operation from regreen to maturity stage each year and injected time from 6:30-18:30 each day, and no CO₂ was released at night. The CO₂] was controlled through computer program and could synchronously adjust with wind speed and direction time by a solenoid valve in a release pipe, then it achieved the expected CO₂].【Result】The pot experiment results indicated that elevated CO₂] accelerated the growth process of winter wheat compared with ambient CO₂], jointing stage speeded up of 1 day, flowering period can be 1-2 days in advance, and the whole growth duration was shortened 3-5 days under the same fertilizer level. While as the high nitrogen could prolong the growth duration, the flowering period can be extended by 1-2 days, filling period by 4-5 days, synchronous alleviated the accelerative effects of elevated CO₂] on growth process; High CO₂] enhanced winter wheat yield about 16.0% via increased grain number per spike and grains weight significantly, and photosynthesis of flag leaves was enhanced by 13.7% compared with ambient CO₂]. Under elevated CO₂] conditions, higher application of nitrogen fertilizer could increase the yield of winter wheat about 50%，enhance the photosynthesis increase rate about 2.5% and transpiration about 13.5% compared with low nitrogen fertilizer supply. That means the nitrogen fertilization can not only promote the high CO₂] positive effect, but still plays a more important role to maintain a stable and higher yield of winter wheat even with CO₂] enrichment conditions; Moreover, elevated CO₂] can increase the grain number per spike by 3.69% compared with ambient CO₂], higher nitrogen increased by 3.43% compared with low nitrogen, the dual role of high nitrogen and high CO₂] increase grain number highest of 38.37 grains/ear, low nitrogen and ambient CO₂] treatment had the lowest level of spike grain numbers, which indicated high CO₂] has the slightly higher positive effects than that of a purely nitrogen treatment on grain number. Dual effects of high CO₂] and nitrogen had the most positive effects on grain number, but the effects had no obvious difference if these measures are used separately. High CO₂] increased grain weight by 5.3%, and if it combined with high nitrogen that the grain weight could increase 7.3%. All these showed that nitrogen promoted the positive effects of high CO₂] on grain weight.【Conclusion】Therefore, under future climate change conditions, higher CO₂] has positive effects to enhance yield of winter wheat and has obvious positive interactions with nitrogen, high nitrogen can extend the growth period which mitigate the shorten growth duration by higher CO₂], improve photosynthesis and promote CO₂ fertilization effects. Higher CO₂] could increase yield via high grain number per spike and grains weight which could be considered for wheat breeding.