【作者】 滕中华；

【导师】 王三根；

【作者基本信息】 西南大学 ， 作物学， 2009， 博士

【摘要】 世界上近一半人口,包括几乎整个东亚和东南亚的人口,都以稻米为食。中国稻作面积约占世界稻作总面积的1/4,占全国粮食播种面积的1/3,而产量则约为世界上稻谷总产量的37%,近全国粮食总产量的45%。近年来,全球变暖引起的水稻热害发生日趋频繁、严重,对我国的水稻生产带来粮食安全隐患。本研究从33份美国稻与13份国内水稻中,筛选出对高温相对较钝感的材料（K30）,作为本试验的耐热对照材料,通过人工气候室精确控温,在水稻生长灌浆结实期设置高温处理,系统研究水稻避热抗热的生理机制和高温胁迫对稻米品质形成的机理影响。研究主要结果如下:1灌浆结实期高温胁迫对水稻光合及蒸腾特性的影响高温处理下,西农优30和富优1号两个水稻品种的叶绿素SPAD值低于对照,随着灌浆结实进程,叶绿素含量继续下降;在水稻灌浆结实期,K30和21两个材料的高温和适温处理的净光合速率（Pn）都呈下降趋势,就两个材料比较而言,高温胁迫下灌浆结实前期（5-10 d）两者的Pn比较接近,但灌浆结实中后期（20-30 d）,K30的Pn明显高于21;高温下,K30和21两个材料的气孔导度（Gs）、胞间CO₂浓度（Ci）和蒸腾速率（Tr）都高于对照;灌浆结实期高温胁迫下,水稻叶片的水分利用效率（WUE）变化有所不同:K30的WUE的变化平稳,最大值与最小值相差21.6%,作为对照的适温处理,WUE出现较大波动,最大值与最小值相差达49.4%,灌浆前期（5-15d）高于高温胁迫处理,而后期（20-30 d）低于高温胁迫处理。两种温度处理下21的WUE变化在20-30 d期间表现较大的波动,整个灌浆结实期,高温胁迫下WUE都低于对照;灌浆结实期K30和21两个材料表观CO₂利用效率（CUE）表现在适温下,变化趋势相同,灌浆前期上升,灌浆中后期,逐步下降,21的CUE高于K30。高温胁迫下,K30的CUE先明显下降（5-10 d）,再逐步上升（5-25 d）,最后下降;21的CUE呈下降趋势;K30和21两个材料在高温和适温处理下表观量子效率（AQY）动态表现出较一致的变化趋势:灌浆结实期前期的AQY高,随籽粒灌浆进程的推进,AQY不断降低;21的高温处理和适温处理在前中期的AQY比较接近（5-20d）,后期（25-30d）高温处理的则明显低于对照（30d时,低57.5%）,K30高温处理下的AQY在整个灌浆结实期都低于对照。2灌浆结实期高温胁迫对叶绿素荧光动力学的影响以西农优30和富优1号为材料,研究灌浆结实期高温胁迫下叶绿素荧光动力学的变化特征。结果显示,高温处理材料的F_o不断上升:与对照相比,高温胁迫使西农优30在灌浆中后期F_o分别上升8.61%和26.43%,富优1号也分别上升5.02%和12.21%;整个结实期,高温胁迫下西农优30和富优1号两个品种的F_v/F_o和F_v/F_m均低于对照,而且都呈下降趋势。高温处理下西农优30的F_v/F_o和F_v/F_m从7 d到28 d分别下降20.76%和5.35%,而对照的下降值是6.05%和1.23%;高温处理下富优1号的F_v/F_o和F_v/F_m也具有相似的变化;qP在灌浆早期最低,灌浆后14天升至最高,然后逐渐降低,两个材料的表现有所不同:整个结实期,富优1号适温处理的qP低于高温处理;西农优30适温处理的qP在前3个时期都高于高温处理。3灌浆结实期高温胁迫对水稻叶片抗氧化系统的影响以K30和21为材料,研究灌浆结实期高温胁迫对水稻叶片抗氧化系统的影响。结果显示:高温胁迫下K30的SOD活性下降,在灌浆结实后期表现明显,高温处理下K30的SOD活性高于21;高温下K30叶片的POD活性上升,整个灌浆结实期,POD活性高于对照;两种温度处理下21的POD活性,未表现出明显差异;与对照相比,K30和21两个材料都表现出高温胁迫下CAT活性明显升高现象,灌浆结实后期酶活性下降,高温胁迫对K30的CAT活性表现出非常明显的增幅:灌浆结实中期（15 d）CAT活性是对照的6.7倍之多。灌浆结实期的高温胁迫使水稻K30叶片中的可溶性糖含量下降,21的可溶性糖含量在灌浆结实前期（5 d-15d）上升,在灌浆结实后期（15 d-30 d）下降,在灌浆结实后期,两个水稻品种叶片中可溶性糖含量都表现出升高的趋势;高温胁迫下,在灌浆结实期5 d-20 d内K30的脯氨酸含量低于对照,在灌浆结实后期（20 d-30 d）则相反;21表现为在灌浆结实期5 d-20 d内,高温和对照处理的脯氨酸含量较接近,两个水稻品种叶片中脯氨酸含量在灌浆结实后期（20 d-30d）都表现出高温胁迫使脯氨酸含量升高的现象;高温胁迫使两个水稻品种叶片中丙二醛（MDA）含量显著增加;整个灌浆结实期,高温下K30的MDA含量变化幅度不大,对照处理的MDA含量呈上升趋势,21的两种温度处理材料的MDA含量随着籽粒灌浆进程,均表现出明显的上升状态;高温胁迫使K30叶片中可溶性蛋白含量下降,21的可溶性蛋白在灌浆早期5 d至20 d内,表现为高温胁迫使可溶性蛋白含量上升,但灌浆后期（30 d）高温处理的21的可溶性蛋白含量下降,21的可溶性蛋白含量整体上低于K30;热稳定蛋白含量的变化与可溶性蛋白的变化趋势比较一致,K30高温处理材料的热稳定蛋白含量整体上高于21。以西农优30和富优1号为材料,研究灌浆结实期高温胁迫下抗活性氧活力（AORRU）和总抗氧化能力（TARU）变化特征。结果显示,西农优30和富优1号两个品种的AORRU在灌浆结实期均低于对照;灌浆结实前期,高温处理材料的AORRU高于对照,灌浆结实后期,西农优30和富优1号的AORRU分别比对照低45.16%和35.99%;高温胁迫使西农优30叶片中TARU在灌浆结实前期（7 d-14 d）升高,后期（21 d-28 d）下降;富优1号的TARU在灌浆结实期中后期（14 d-28 d）下降,适温下整个灌浆结实期保持较高活力。4灌浆结实期高温胁迫下水稻内源激素的动态变化以K30和21为材料,研究灌浆结实期高温胁迫下水稻叶片和籽粒中内源激素的动态变化规律。结果显示,高温胁迫下,K30叶片中的ABA含量上升,21中的ABA变化不明显,K30籽粒中的ABA含量明显高于对照,灌浆后期,21籽粒中ABA含量比K30下降明显;K30和21的叶片和籽粒中IAA含量都出现灌浆结实后期降低现象;高温胁迫对两个水稻品种叶片中的GA₃变化方向相反,K30的GA₃含量上升,而21的GA₃含量下降,籽粒中GA₃含量在灌浆结实后期降低;高温胁迫下,K30叶片中ZR含量比21保持了更长时间的峰值,高温处理使K30籽粒中的ZR含量比对照增加更明显;高温胁迫下,灌浆结实前期（5-10 d）K30的GA₃叶片/籽粒值高于明显高于21（分别为4.3倍和4.5倍）。5灌浆结实期高温胁迫对水稻淀粉合成相关代谢活动及稻米品质的影响以K30和21为材料,研究灌浆结实期高温胁迫对水稻淀粉合成相关酶活性的影响。结果显示,高温胁迫下,K30和21两个材料的SPS活性和SS活性明显下降;Q酶活性的变化过程:先升后降,灌浆中期酶活最高,两种温度处理下,21的Q酶活性最高值出现在10-15 d左右,K30的Q酶活性最高值出现在10-20 d左右;高温胁迫下籽粒中可溶性蛋白、热稳定蛋白和赖氨酸含量上升。成熟稻米品质分析结果表明,垩白度大幅增加,蛋白质含量上升,千粒重、总淀粉和直链淀粉含量下降。西农优30和富优1号品种的变化看,适温处理下两者的蛋白质含量较接近,经高温处理的富优1号蛋白质含量增加15.1%,而西农优30的蛋白质含量增加达到51.3%;经高温处理的富优1号总淀粉含量降低14.1%,而西农优30的总淀粉含量降低20.5%。更多还原

【Abstract】 Rice grain is used as the main food by half of the world’s population including nearly whole East Asia and Southeast Asia.The Chinese cultivation land area of rice accounts for about 25%of the world,and 33%of the whole cultivation land in China.In recent years,heat injury of rice plants caused by "effects of green house" happens with increasingly frequency,which may bring hidden dangers of food security.In this research,rice plants with heat tolerance were used as material,high temperature stress were set during filling period,the aim was to systematically study the physiological mechanism and effects on grain quality under high temperature.The main results are as follows:1.Effects of high temperature stress on photosynthesis and transpiration during filling periodUnder high temperature,the chlorophyll content was lower than control in Xinongyou 30 and Fuyou 1,and decreased during filling period.The net photosynthetic rate（Pn） also dropped under both high and optimal temperature in two cultivars K30 and 21.Compared with 21,Pn was nearly same in K30 during the first filling period,but obviously higher during the mid and late filling period（20-30 d）.Under high temperature,stomatal conductance（Gs）,CO₂ concentration inside leaf （Ci） and transpiration rate（Tr） were above the control.Change of water use efficiency（WUE） in two cultivars was different,the range of WUE was small in K30 treated under high temperature（the range was 21.6%between the maximum and minimum）,while larger in K30 control（the range was 49.4%）;WUE of K30 treatment was below control during the first filling-period（5-15d）,while above the control during the late period（20-30 d）.Under high and optimal temperature,the change scope of WUE of 21 was great during the late filling period（20-30 d）,and WUE of control was lower than treatment in 21 during the whole filling period;Under optimal temperature,Carbon dioxide use efficiency（CUE） increased during the first filling period in both two cultivars,then gradually decreased during the mid filling period,CUE of 21 was higher than K30.Under high temperature,CUE of K30 dropped during first filling period（5-10 d）,then gradually rised（5-25 d）,and last dropped to the lowest;CUE of 21 showed downtrend during filling period.The trend of apparent quantum yield（AQY） was identical in both two cultivars under high and optimal temperature:AQY was higher during first filling period,then gradually declined.Compared with control,AQY of 21 treatment was similar during first and mid filling period（5-20 d）,but obviously lowered during the late filling period（25-30 d）;AQY of K30 treatment was below the control under high temperature during the whole filling period.2.Effects of high temperature stress on chlorophyll fluorescence kinetics during filling periodUsing Xinongyou 30 and Fuyou 1 as material,the characteristics of chlorophyll fluorescence kinetics were studied.The results showed that F_o increased during filling period,compared with control,F_o increased 8.61%and 26.43%during mid and late filling period in Xinongyou 30,also 5.02%and 12.21%in Fuyou 1.Compared with control,both F_v/F_o and F_v/F_m was low in two cultivars and declined during the whole filling period;F_v/F_o and F_v/F_m dropped 20.76%and 5.35% from 7 d to 28 d in Xinongyou 30 treatment,while 6.05%and 1.23%in Xinongyou 30 control,and the same trend showed in Fuyou 1,qP was lowest in the first filling period,highest in 14 d,then gradually decreased.The two cultivars differed,compared with control,qP was beyond during the whole filling period in Fuyou 1,while below during the first three stages in Xinongyou 30.3.Effects of high temperature stress on antioxidant system during filling periodUsing K30 and 21 as material,effects of high temperature on antioxidant system during filling period were studied.The results showed that activity of superoxide dismutase（SOD） declined in K30,especially in the late filling period under high temperature,compared with 21,activity of SOD increased in K30.Activity of peroxidase（POD） of K30 also showed higher under high temperature, but the variety of POD activity was not observed in 21 under high and optimal temperature.In K30, catalase（CAT） activity increased most obviously among the three enzymes under high temperature: the CAT activity of treatment was 6.7 times as great as the control.In K30,soluble sugar content declined under high temperature,in 21,soluble sugar content rised during the first filling period（5-15 d）,falled during the late filling period（15-30 d） compared with the control.In the late filling period,soluble sugar content of two cultivars had rising trend.In K30,proline content of treatment was lower than control during the filling period of 5-20 d,but higher during the filling period of 20 -30 d.Malondialdehyde（MDA） content increased in two cultivars under high temperature,the change scope of MDA content in K30 treatment was narrow,while MDA content in K30 control ascended markedly.Under high temperature,soluble protein content descended in K30 leaf,first ascended in 21 leaf during filling period of 5-20d,then dropped during the filling period of 20-30d. Compared with 21,soluble protein content had high level in K30 leaf.The dynamic change of thermostability protein content was identical with soluble protein,the thermostability protein content in K30 was higher than 21.Using Xinongyou 30 and Fuyou 1 as material,the dynamic change characteristics of active oxygen resistance reactivity units（AORRU） and total antioxidant reactivity units（TARU） were studied.AORRU of treatment was lower than the control during the whole filling period;in the late filling period,AORRU decreased to 45.16%and 35.99%in Xinongyou 30 and Fuyou 1 respectively contrast with the control.TARU increased in first filling period in Xinongyou 30 under high temperature,while decreased in the late filling period.TARU descended in Fuyou 1 in mid and late filling period（14-28d）,and TARU of treatment was lower than control during the whole filling period.4.Dynamic variation of endogenous hormones in leaf and grain during filling period under high temperature stressUsing K30 and 21 as material,dynamic change of endogenous hormones in leaf and grain during filling period was studied.In leaf,abscisic acid（ABA） content increased in K30,but no change of ABA content appeared in 21 under high temperature.In grain,ABA content of treatment was much higher than control in K30.During the late filling period,ABA content of grain was lower in 21 than K30.Indole-3-acetic acid（IAA） content of grain declined in both cultivars during the late filling period.In leaf,the effect of high temperature on gibberellic acid（GA₃） content of two cultivars was opposite:increased in K30,while decreased in 21.In grain,GA₃ content dropped in the late filling period.Compared with 21,the period of zeatin nucleotide（ZR） highest content was long under high temperature in leaf in K30,and higher content of ZR of treatment was found in K30 grain.Under high temperature,ABA ratio of leaf to grain in K30 was much higher than 21 during the first filling period of 5 and 10 d（4.3 and 4.5 times respectively）.5.Effects of high temperature stress on the metabolism of starch and grain quality during filling periodUsing K30 and 21 as material,effects of high temperature on the metabolism of starch and grain quality during filling period was studied.In two cultivars,activities of sucrose-phosphate synthase（SPS） and sucrose synthase（SS） declined under high temperature.The change process of starch branch enzyme（SBE or Q enzyme） was from rising to falling,the highest activity appeared in the filling period of 10 to 15 d in 21,and 10 to 15 d in K30.The content of soluble,thermostability protein and lysine m grain increased under high temperature.The results of mature grain analysis showed that chalkiness accrued,protein content increased, 1 000 grain,total starch and amylose content decreased in four cultivars.Comparing the two cultivars of Xmongyou 30 and Fuyou 1 under optimal temperature,protein content was approximate. Protein content ascended 15.1%1 after high temperature stress in Fuyou,while 51.3%in Xinongyou 30.Total starch content dropped 14.1%after high temperature stress in Fuyou 1,while 20.5%in Xinongyou 30.更多还原