【作者】 王佩玲；

【导师】 李世清；

【作者基本信息】 西北农林科技大学 ， 生态学， 2010， 硕士

【摘要】 大气CO2浓度升高对植物生长影响是当前国内外研究的热点问题之一,该研究在国外开展较早,而我国主要研究开始于20世纪90年代末,主要集中在大气CO2浓度增加对作物生物学指标、生理指标以及产量性状影响方面的研究,将几种因素综合考虑的较少,资料相对贫乏,而且一些结果仍需进一步验证。本研究采用开顶式气室(Open Top Chambers,OTCs),以冬小麦(Triticum aestivum L.)为供试作物,通过土培实验,研究大气CO2浓度倍增对生长在不同介质施氮水平(不施氮(N0)、每千克土施氮0.15g(N1)和0.30g(N2))下冬小麦品种光合荧光特性、生长发育、冬小麦产量构成及氮素分配利用的影响。研究获得以下主要进展:1.实验表明,与背景CO2浓度相比,大气CO2浓度升高对不同生育时期冬小麦叶片的叶绿素含量、各荧光参数值和净光合速率均有影响,不施氮条件下随大气CO2浓度增加各主要生育期叶片叶绿素含量均显著降低,Fo值有不同程度升高,Fm、Fv、Fv/Fm和Fv/Fo值及净光合速率有不同程度地下降,这表明大气CO2浓度升高使低氮营养下作物PSⅡ受到的光损伤增加,对其电子传递、电子受体QA氧化还原、最大光化学效率和潜在活性有一定的抑制作用,光合系统的光能转换和碳固定能力降低。同时,不同介质施氮水平对冬小麦各主要生育期叶片叶绿素含量、荧光参数值和净光合速率也有不同程度的影响,在高浓度CO2下,施氮可使两个基因型冬小麦叶绿素含量和Fm、Fv、Fv/Fm和Fv/Fo明显增加,N1、N2水平显著高于N0水平,但两个施氮处理(N1和N2)间差异大都不显著。2.大气CO2浓度倍增对两基因型冬小麦叶面积、株高、成熟期茎长、穗下第一节间长、穗长有均有一定影响,但影响程度与介质施氮有关,N0处理时,大气CO2浓度倍增对冬小麦生长状况影响均不显著,基因型间差异也不明显;N1、N2处理下,大气CO2浓度倍增后,除叶面积外,显著增加了其它各个生长指标值。介质不施氮时,大气CO2浓度升高对小偃22号和小偃6号产量的影响不明显,介质施氮后大气CO2浓度升高使得两基因型冬小麦的产量显著增加,对小偃22号产量的影响大于小偃6号,穗数和穗粒数增加是提高产量的主要原因。另外,大气CO2浓度倍增后株高的变化与穗下第一节间长增加相关,而且均受施氮水平调节。同时,增加施氮水平有利于大气CO2浓度升高后叶片保持较高光合面积,接受更多光能。3.大气CO2浓度倍增后对两基因型冬小麦的氮素含量有一定影响,但影响大小取决于介质施氮水平、器官部位和生长时期。CO2浓度倍增升高不利于增加冬小麦各器官氮素含量,在生育后期表现的尤为明显,其中,对根部的影响较小,对其它部位影响较为显著。供氮介质不足时,大气CO2浓度倍增对两基因型冬小麦成熟期氮素累积量有负面效应,小偃6号和小偃22号氮收获指数也明显下降,增施氮肥后,当大气CO2浓度升高时作物体氮素累积量显著增加,氮收获指数均随施氮量增加而增加,以高产高氮效品种小偃22号表现尤为明显。以上结果初步证明,在本实验条件下,当介质氮素供应不足时,大气CO2浓度倍增对作物代谢及生长发育等指标总体上表现为抑制作用或者效应不显著,但介质施氮肥后可以明显改善这种由大气CO2浓度升高给作物带来的不利影响,可明显促进作物生长发育,说明大气CO2浓度升高与介质施氮对冬小麦生长发育具有明显正交互效应。研究结果虽然充分证明了基本假设“大气CO2浓度倍增和介质施氮水平对作物物质生产及氮素利用存在正交互作用”,但对“不同品种影响程度与施氮水平有关”尚未完全证明,且对大气CO2浓度对作物的影响机理尚未研究清楚,在今后的实验中仍需进一步研究证明。更多还原

【Abstract】 The studies on the effect of CO2 concentration elevation on plants have been one of the hot issues. This research begun with1990s in China, and later than abroad. The research mostly focus on biological, physiological and yield characters of crops.There still need some experiments to proof the effects of all factors on crops because most of the study only took into account of CO2 concentration or combined it with nutrient and water, respectively. Our study used Open Top Chambers equipment to study the effect of elevated CO2 on photosynthetic fluorescence characteristics, growth, nutrient distribution and yield components of winter wheat (Triticum aestivum L.) which growing under three levles of nitrogen application (N0, N1 and N2, representing 0, 0.15 and 0.30 g nitrogen per kilogram soil, respectively). Major conclusions are as follow:1. The results showed that, compared with the background CO2 concentration, elevated CO2 had effect on chlorophyll content, fluorescence parameters and net photosynthetic rates of wheat leaf at different growth stages. Under no nitrogen application, CO2 concentration elevation significantly reduced chlorophyll concent at major growth stages, increased inordinately Fo , and decreased inordinately Fm, Fv, Fv / Fm, Fv / Fo and net photosynthetic rate,too.This indicated that under low nitrogen nutrition, elevated CO2 could increase light damage of PS II, inhibited the electron transfer, electron acceptor QA redox, photochemical efficiency and the potential reactivity of PS II and light energy conversion system and photosynthetic carbon fixation capacity. Meanwhile, different nitrogen levels also influcenced chlorophyll content, fluorescence and net photosynthetic rate of winter wheat leaf which at the different growth stages. Under elevated CO2 concentrations, chlorophyll content, Fm, Fv, Fv / Fm and Fv / Fo of two winter wheat varieties significantly higher in nitrogen application treatments(N1, N2) than these in no nitrogen applicationment treatment(N0), while there was no significant difference between two nitrogen application treatments2. CO2 concentration elevation affected leaf area, plant height, mature stem length, ear length of two wheat varieties. The influences were associated with nitrogen level. Under N0, Elevated CO2 did not change the growth of wheat, While under N1 trestment and N2 treatment, elevated CO2 increased all the growth indexs except leaf area. Similarly, the yield of wheat in CO2 concentration treatments was increased only under nitrogen application. The production change of Xiaoyan22 was much bigger than that of Xiaoyan6 for CO2 concentration elevation. The production increase was primarily due to the enhancement of spike number and grain number per spike. In addition, the change of wheat height and its composition after CO2 concentration increase were associated with the increaseing of stem frist node length and ear length. Both of them were controled by nitrogen application level. Meanwhile, it was good for the leaf maintaining a high photosynthetic area to receive more light through using more nitrogen.3. Elevated CO2 also influenced the nitrogen content of two wheat genotypes, and the infucenced degree depended on nitrogen application levels, organs and growth stages. It was not so conducive to nitrogen content in different organs of winter wheat, especially at late growth stage. The effect of elevated CO2 on the root was smaller than that on other parts. Elevated CO2 concentration would have negative effect on nitrogen accumulation at maturity stage because of nitrogen deficiency. The harvest index of nitrogen decreased significantly both in Xiaoyan6 and Xiaoyan22. After nitrogen application, Nitrogen accumulation increased significantly in elevated CO2 concentration and higher than that in the background concentration. Nitrogen harvest index increased along with the increase of nitrogen application level, especially in Xiaoyan 22 which was the high yield, high nitrogen efficiency variety4. In total, CO2 concentration elevation had inhibition or no significant effect on growth and metabolism of wheat under nitrogen deficiency, but it obviously stimulated crop growth under nitrogen application, which showed that a interaction between CO2 concentration elevation and nitrogen application was positive on winter wheat. Although the basic assumption that“CO2 concentration increased and nitrogen application on crop production and nitrogen utilization of material there is a positive interaction.”was proved,“the level of N has something to do with effect on different varieties”lacked enough evidence. It would need further research on the impact mechanism of the CO2 concentration on wheat in the future.更多还原