【作者】 倪艳利；

【导师】 郑有飞；

【作者基本信息】 南京信息工程大学 ， 环境科学， 2011， 硕士

【摘要】 大气气溶胶是目前世界所关注的重大环境问题之一,大气气溶胶会通过直接或间接作用影响造成作物光合作用下降,导致作物减产。为进一步探明大气气溶胶所产生的太阳辐射减弱对农作物光合生理及荧光特性的影响机制,本研究采用完全随机分组的方法,在大田试验条件下,设置了(CK,自然光)、处理1(T1,15%自然光)、处理2(T2,20%自然光),处理3(T3,40%自然光)和处理4(T4,60%自然光)五个不同太阳辐射减弱处理,对大田生长的冬小麦进行太阳辐射减弱处理,较为系统的研究了研究了太阳辐射减弱对冬小麦光合作用、荧光参数、营养物质及抗氧化体系的影响作用及其机制,为防治大气气溶胶及其产生的太阳辐射减弱对我国农业生产的影响提供科学依据。主要结果如下：(1)太阳辐射减弱显著增加了冬小麦光合色素的含量,增强光能的吸收,是作物对太阳辐射减弱的适应性反应,即通过提高叶绿素含量促进光能的吸收能力,弥补光能不足,尽量维持物质的正常代谢。同时冬小麦叶绿素a/b比值降低,降低幅度也随遮阴强度的增加而加大,表明其受到光抑制的可能性增大。另外增大了植物类胡萝卜素Car和叶黄素含量,延缓了冬小麦叶片的老化速度。(2)太阳辐射减弱显著降低了光合速率(Pn)。不同辐射减弱条件下冬小麦Pn日变化差异较大,日最高值表现为CK>60%自然光>40%自然光>20%自然光>15%自然光,其中CK呈双峰曲线变化,有明显的“午休”现象,其他各处理均呈单峰型曲线变化,“午休”现象不明显,但峰值出现时间滞后。相关分析表明,太阳辐射减弱是影响Pn日变化的主导因子,但其他因子也显著影响Pn。与CK相比,60%和40%自然光处理中光合有效辐射(PAR)、叶温(T1)、气孔导度(Gs)和蒸腾速率(Tr)与Pn均呈显著正相关,表明上述因子对Pn有正效应,Ci和Ls在上述两处理中与Pn呈显著负相关,但在20%和15%自然光处理中与Pn呈显著正相关,说明太阳辐射强度高于40%自然光时冬小麦叶片胞间二氧化碳浓度和气孔导度限制值对Pn有负效应,太阳辐射强度低于40%自然光时则为正效应。(3)太阳辐射减弱效应显著降低了Chla/Chlb和光合速率(Pn)。Fv/Fm、qP、Y(NO)、(1-qP)/NPQ及实际光量子效率(Yield)均随太阳辐射强度下降而呈现下降的趋势,而NPQ、Y(NPQ)和L (PFD)呈上升趋势。可见,太阳辐射减弱时冬小麦叶片会下调PSⅡ原初光化学反应的电子传递效率来适应光能不足的逆境胁迫(光化学猝灭系数qP的下降),同时降低电子递体(PQ)的活性(量子效率Yield降低),增加叶片热耗散,导致光合能力降低。(4)太阳辐射强度减弱抑制冬小麦叶片可溶性糖和可溶性蛋白的合成,增加作物总游离氨基酸的含量,冬小麦植株的代谢由碳代谢为主转向氮代谢为主,不利于冬小麦叶片内有机营养物质的合成与积累。同时抗氧化酶防御系统CAT、POD等保护酶活性降低,丙二醛含量降低,电导率下降,冬小麦植株体内抗氧化防御体系处于较低活性状态。更多还原

【Abstract】 In the recent years, global dimming of solar irradiance is growing due to increase of aerosols, air pollutants and population density. In order to elucidate the effects of reduced solar irradiance on diurnal changes of photosynthetic rate of winter wheat cultivar, we conducted a field experiment in Nanjing city by using the Triticum aestivum L. (cv.Yang mai 13) as the experimental plants. Starting from jointing to maturity, the plants were subjected to 5 shading treatments, i.e. 100%(CK),60%(T1),40%(T2),20%(T3) and 15%(T4) of total incident solar radiation, with the first one as control (CK). The growth of winter wheat field on to solar radiation is systematically weakened processing, studied the solar radiation abate study on winter wheat photosynthesis, fluorescence parameters, nutrients and antioxidant system, its impact and mechanism for prevention and control of atmospheric aerosol its solar radiation weaken the influence of agricultural production in China to provide scientific basis. Main results are as follows:1) Reducing solar radiation significantly increases chlorophyll and lutein content of winter wheat in the grain filling stage, The sun radiation weakened significantly increased winter wheat photosynthetic pigment content, strengthen the light energy absorption, is weakening of solar radiation of crop that is by improving the adaptie response to promote chlorophyll content and make the light energy absorbing ability insufficiency, try to maintain material light the normal metabolism. Meanwhile winter wheat chlorophyll a/b ratio lower reduction with shade, the increase of strength and that their popularity, and increase the possibility of photoinhibition increase. Another increased plant carotenoids and lutein content, delaying the winter wheat leaf aging speed.2) Aditionally, the main factors responsible for photosynthetic rates of each shading treatments were also tested via correlation analysis. Results show that reduced solar irradiance significantly increased the contents of chlorophyll and lutein, but decreased the net photosynthetic rate (Pn) of winter wheat. The diurnal changes of photosynthetic rate varied significantly according to the shading treatments, in which the maximums of Pn presented a pattern of CK>T60>T40>T20> T15. During the experimental periods, the Pn from CK exhibited a "double peak" diurnal curve, while the curves for all the other shading treatments generally showed a change of "single peak", and their maximum Pn were lagged behind that of CK. Correlation analysis shows that reduced solar irradiance was the main factor that influenced the Pn diurnal curves significantly, although physiological parameters also played important roles in determining the variation of Pn. Compared with CK, the photosynthesis active radiation (PAR,) leaf temperature (TL), stomatal conductance (Gs) and Transpiration rate (Tr), in the treatment of T6o and T40 were significantly positively correlated to Pn, indicating that these parameters have positive impact on Pn under reduce solar irradiance condition. On the contrary, the intercellular CO2 concentration (Ci) and stomatal limitation (Ls) were significantly negatively correlated to Pn in T60 and T4oas compared to CK, and in T40 and T20, the correlations reversed, implying that the Ci and Ls had negative(or positive) impact on Pn when solar irradiance was higher (or lower) than 40% of incident solar irradiance. 3) Reducing solar radiation significantly decreases the Chla/Chlb and photosynthetic rate (Pn). Fv/Fm, qP, Y (NO), (1-qP)/NPQ and the actual photochemical efficiency (Yield) are increased with solar radiation intensity decreased,and show a downward trend, but NPQ, Y (NPQ) and L(PFD) was rise. Visible, less solar radiationis cut in winter wheat leaves, when the primary photochemical reaction of PSⅡelectron transfers efficiency to meet the energy shortage of Stress (a decline in photochemical quenching qP).meanwhile, reducing the electronic delivery of the body (PQ) activity (quantum efficiency Yield was lower),is to increase the heat dissipation leaves, resulting in reduced photosynthetic capacity.4) Reducing solar radiation significantly influences synthesis of soluble protein and soluble sugar of winter wheat leaves, increases the content of total crop free amino acid winter wheat plant metabolism mainly by carbon metabolism to nitrogen metabolism is given priority to, unfavorable to organic nutrients in winter wheat blade of synthesis and accumulation. Meanwhile antioxidant defense system, Such as CAT and POD, Protective Enzyme Activity of reducing and malondialdehyde content of reducing and conductivity of decline in winter wheat plants in a state of Lower Activity of Antioxidant defense system.更多还原