【作者】 邵瑞鑫；

【导师】 上官周平；

【作者基本信息】 中国科学院研究生院（教育部水土保持与生态环境研究中心） ， 生态学， 2011， 博士

【摘要】 土壤水分不足和氮素亏缺是限制作物高产的主要因素,施用氮肥因此成为旱作条件下实现农业高产的主要途径之一。本实验由室内控制实验与大田试验两部分组成:室内实验分析了水分和氮素亏缺下小麦光合性能指数及抗逆信号物质的变化;大田试验在0³60kg/hm²范围内设计4个氮肥水平,研究了氮肥水平对小麦光合生理生态特性和土壤呼吸的影响。本研究取得如下主要结论:（1）不同品种小麦苗期受到水分和氮素胁迫时光合性能指数下降的主要原因不一。郑麦9023遇胁迫时光合性能指数下降主要是由于光合电子传递链的破坏和叶片水分的丧失;而长武134在水分亏缺时光合电子传递受到影响,氮素亏缺时天线色素的光捕获能力和反应中心的活性减弱,水分和氮素亏缺共同胁迫时,光捕获能力和光合电子传递在一定程度上受到影响。水氮胁迫对小麦光合作用的影响程度和内源NO及CTK水平密切相关。长武134在受胁迫时NO信号没有明显减弱,iP+iPA和Z+ZR向DHZ+DHZR转化率较高,有利于清除胁迫产生的ROS,因此其光合机构对胁迫的忍耐程度强于郑麦9023。（2）在0¹80kgN/hm²范围内,增施氮肥能明显提高小麦拔节后不同生育时期的叶绿素含量、光合速率和光合性能指数,且不同的小麦品种对氮肥用量的需求不同。施用高水平的氮肥对长武134光合作用的调节效果明显,例如在N180和N360两个处理水平时的Chl和PI显著高于其它处理,且在灌浆期和成熟期由于长武134叶绿素含量明显高于郑麦9023,因此即使在生育后期也能维持较高的光合速率和光合性能指数。但是在0¹80kgN/hm²范围内,不同氮肥水平均能明显增加郑麦9023的Chl和光合性能指数值,而相对于N180处理,N360处理的PI及其各参数值和Pn降低。（3）施氮处理与不施氮处理的红边参数差异显著。小麦光合特性、叶片氮含量和生物量除与Lwidth呈负相关性外,与其它红边参数均呈正相关,且与REP之间的相关系数高于其他参数。由于叶片N含量或Chl含量的增加,施用氮肥处理的REP、N90和N180处理的Lo均呈现“红移”现象。350⁶80nm和750¹100nm这两个波段范围可作为检测小麦氮素营养的冠层光谱敏感波段。（4）除了具备较高的光合能力,干物质和N的积累与分配也是决定小麦产量的主要原因。尽管长武134具有较强的抗旱性,且成熟期的光合持续期比郑麦9023长,但是其只有在高氮（N180和N360）处理时,花前营养器官积累N素向籽粒中的转移率和N素在籽粒中的分配才会明显增加,总体上仍低于郑麦9023,推测长武134是高氮低效性品种。适当增施氮肥（≤180kgN/hm²）能促进拔节后不同生育时期干物质的积累和收获期干物质向地上部分的分配,降低根冠比,有利于干物质向籽粒中转移,这也是氮肥增产的主要原因之一。此外,郑麦9023在各种氮肥处理中的地上生物量均高于长武134,长武134的产量因此低于郑麦9023。（5）在小麦的整个生育时期内,土壤CO₂的释放速率受到土壤温湿度、生物量和氮肥水平的综合影响。总体来看:0¹80kgN/hm²的范围内,施用氮肥能显著增加小麦生育期间土壤CO₂的释放速率和总量,当施氮量超过180 kgN/hm²时,土壤CO₂的释放速率和总量并没有再明显增加;土壤CO₂的释放速率和土壤温度成正相关,与土壤水分成负相关,土壤温度比土壤水分对土壤呼吸速率的影响显著;当土壤水分接近植物萎蔫点时（8.5%）,土壤温度对土壤呼吸速率的影响减弱,土壤呼吸速率开始下降。麦田不同氮肥处理小区的土壤CO₂释放总量分别比裸地高42%, 65%, 90%和95%（N0,N90,N180,N360）,说明增施氮肥能提高根系呼吸占土壤呼吸的比例。更多还原

【Abstract】 Water and nitrogen nutrition deficit are the key factors limiting agricultural production in arid and semiarid region, thus it is essential to fertilize nitrogen for increasing agricultural productivity under rain-fed conditions. The experiment was composed of indoor experiment and outdoor experiment. First part is to discuss the changes of photosynthetic performance index and adverse resistance signal of wheat under water and nitrogen deficiency condition. Then four nitrogen levels were devised in the range of 0-360 kgN/hm² to survey the effects of the nitrogen level on the physio-ecological characteristics and soil respiration. The main conclusions of this study were as follows:（1） It indicated that the reason of the decline of Photosynthetic Performance Index is different between the two varieties under water and nitrogen deficiency condition. The main reason of Zhengmai 9023 was because of destoy of photosynthetic electron transport chain and the loss of leaf water. The photosynthetic electron transport of Changwu 134 was affected by drought stress. The capacity of light-harvesting of antenna pigment and the activity of reaction center decreased under nitrogen stress. The capacity of light-harvesting and photosynthetic electron transport were affected to some extent under drought and nitrogen stress. But the influence degree of drought and nitrogen stress on photosynthetic capacity was closely related with the contents of endogenous NO and CTK. NO signal of Changwu 134 was not weakened obviously and the high conversion of iP+iPA and Z+ZR to DHZ+DHZR was contributed to scavenge the ROS which produced under stress condition. Therefore, the tolerent degree of its photosynthetic apparatus was better than Zhengmai 9023. （2） Chlorophyll content, photosynthetic rate, photosynthetic capacity index of the different developmental stage was improved by increasing nitrogen after jionting stage in renge of 0-180 kgN/hm², it is different to need different nitrogen level for different wheat varieties. The regulative effect of nitrogen was obvious on photosynthesis of Changwu 134, for example, the Chl and PI of N180 and N360 were significantly higher than the other treatments. The chlorophyll content of Changwu 134 was higher than Zhengmai 9023 in filling stage and ripening stage, so it could maintain higher photosynthetic rate and PI value in late growth stage. With the nitrogen level increasing in the range of 0¹80 kgN/hm², the Chl and PI of Zhengmai 9023 were improved and the value of PI and its parameters and Pn in N360 were lower than that in N180.（3） The red edge parameters between nitrogen and no-nitrogen treatments had a significant difference. There was a significant negative correlation between photosynthetic characteristics, leaf nitrogen contents and biomass of wheat with Lwidth. It had a positive correlation with other red edge parameters and higher correlation coefficient with REP than others. With the N content or Chl content of leaf increasing, red shift was observed in REP fertilized nitrogen and Lo with N90 and N180. 350-680 nm and 750-1100 nm could serve as canopy spactra sensitive band to detecte nitrogen nutrition.（4） The accumulation and distribution of dry matter and N were the main reasons to determine wheat yield except higher photosynthetic capacity. Though Changwu 134 had an obvious drought resistance and photosynthetic duration in ripenning stage than Zhengmai 9023, its N transferation from pre-flowering vegetative organs to grain and the N distribution in grain was increased obviously only on 180 kg N/hm² and 360 kgN/hm². But it was lower than Zhengmai 9023 in general. Accordingly, Changwu 134 was a variety that needed high N and had lower efficiency. To increase nitrogen application（≤180 kgN/hm²）could promote the dry matter accumulation of different growth stages after jionting, the dry matter distribution to aerial part in harvest stage, reduce root-shoot ratio which was contributed to the dry matter transfer to grain and one of the main reasons why N could increase yield. In addition, the biomass of aerial part of Zhengmai 9023 in every N treatment was higher than that of Changwu 134. So the yeild of Changwu 134 was lower than Zhengmai 9023.（5） Soil CO₂ emission rate was affected by the root biomass, soil temperature and soil humidity and N levels in the growth stage of wheat. With the N application increasing in the range of 0-180 kg/hm², the total soil CO₂ emission and rate were increased significantly by N application. When nitrogen level was above 180 kg/hm², the total soil CO₂ emission was not increased significantly. Soil CO₂ emission rate had a positive correlation with soil temperature and a negative correlation with soil humidity. Besides, there was consistent season change between soil CO₂ emission rate and soil temperature. Soil temperature had a great influence than soil humidity on soil CO₂ emission rate. When soil humidity closing to soil wilting poin（t8.5%）, the influence of soil temperature was not obvious on soil CO₂ emission rate. The soil CO₂ emission rate began to decrease. The total soil CO₂ emission rate of 0,90,180,360 kgN/hm² in wheat field were 42%, 65%, 90% and 95% higher than bare land respectively. It indicated that increasing N could promote the ratio of root respiration to soil respiration.更多还原