【作者】 冯波；

【导师】 董树亭；

【作者基本信息】 山东农业大学 ， 作物栽培学与耕作学， 2014， 博士

【摘要】 小麦是我国第三大粮食作物，在我国国民经济中占有重要地位。近年来，气候变暖引起的小麦热害发生日趋频繁与严重，对我国小麦生产带来安全隐患。小麦的穗、穗下节间和旗叶鞘等非叶绿色器官光合耐逆性强，能够补偿生育后期绿叶面积减少而造成的灌浆物质不足，可以作为突破产量限制，实现高产与抗逆结合的途径。研究高温逆境下小麦非叶器官的光合性能以及对产量的贡献意义重大，并将为小麦高产、抗逆稳产栽培的群体调控寻求理论依据。选用不同耐热性小麦品种济麦22（JM22）、新麦26（XM26）、056852品系（056852）以及藁城8901（GC8901）作为供试材料，灌浆期在大田搭棚进行高温处理，较系统地研究了灌浆期高温胁迫对冬小麦不同绿色器官以及产量形成的影响，基本明确了小麦不同绿色器官的光合特性、耐热避热特性以及对小麦产量形成的影响，并进一步分析了其生理机制。研究主要结果如下：1、冬小麦不同绿色器官对产量的贡献研究开花期进行剪叶包穗包茎处理，研究发现，对籽粒贡献率最大的是穗部，为41.15%-47.36%；其次是叶片，其贡献率为35.98%-43.89%；再次是贮存在茎秆和叶鞘内贮存物质向籽粒中的转运；然后是茎秆和叶鞘的光合贡献；最后是裸露穗下节间和旗叶鞘的光合贡献。不同耐热性品种各个绿色器官对群体产量的贡献在总的趋势上趋向一致。对小麦旗叶和穗部分别进行13C喂饲的结果发现：不管是对穗部还是旗叶进行喂饲，最终13C所占该器官总C的比例都是以穗部最高，其次是茎秆加叶鞘，然后是叶片，最后是颖壳。对穗部和旗叶分别饲喂的结果比较发现，对穗部进行喂饲的光合产物中13C所占该器官总C的比例无论在籽粒，颖壳还是叶片上的都要高于对叶片进行13C饲喂的。上述结果表明，穗部的光合同化效率高于叶片。2、高温胁迫对耐热性不同小麦产量形成的影响研究高温胁迫加剧了整株小麦的衰老进程，因为高温胁迫后不同耐热性小麦的植被覆盖指数下降，XM26和GC8901植被覆盖指数下降明显，处理与对照差异显著。高温胁迫减少了不同耐热品种小麦的灌浆持续期，使最大灌浆速率时间提前还使不同耐热品种的最大灌浆速率不同程度的降低。与对照相比，056852最大灌浆速率相对减小的最少；其次是JM22；再次是GC8901；XM26的最大灌浆速率较对照减少最多。高温胁迫降低了小麦的千粒重，造成了最终产量的降低。但是高温胁迫对不同耐热品种的影响不一样。与各自对照相比，千粒重变化大小由高到低依次为XM26>GC8901>056852品系>JM22。籽粒产量变化大小顺序与千粒重变化一致，受高温胁迫而减产最重的是XM26和GC8901，分别比对照减产11.43%和10.05%，而JM22和056852品系减产不大，为6.41%和6.93%。3、高温胁迫对旗叶和穗部光合速率的影响JM22和XM26旗叶净光合速率对高温胁迫响应的变化趋势非常相似，但是两个品种旗叶光合速率变化的幅度大小不一。自胁迫前至胁迫结束当天，非胁迫处理条件下，两个品种旗叶净光合速率都呈缓慢下降的趋势；相反，两个品种胁迫处理的旗叶净光合速率都急剧下降。与各自对照处理相比，JM22旗叶净光合速率在胁迫结束后当天下降了6.6%，在胁迫结束后第10天，旗叶净光合速率下降了59%；XM26旗叶净光合速率在这两个时期分别下降了12.8%和69.9%。旗叶净光合速率下降表明高温加速了旗叶衰老的进程，也表现出高温对旗叶光合功能的抑制作用。与旗叶净光合速率变化相反，高温胁迫使JM22和XM26与各自对照相比其旗叶气孔导度分别增加7.09%和23.67%；高温也使旗叶的蒸腾速率明显升高；但是与旗叶净光合速率的显著下降以及气孔导度和蒸腾速率的急剧变化相比，胞间二氧化碳浓度的变化不显著。分析高温对旗叶气体交换参数的变化，我们可以得出这样的结论：高温对旗叶净光合速率的抑制是非气孔限制。而且高温对旗叶净光合速率的抑制作用具有品种间差异性，这一点可以从XM26旗叶净光合速率变幅显著大于JM22来得以证明。高温胁迫前，所有品种穗部的处理与对照光合表现一致，高温胁迫后穗部光合发生变化，品种间变化不等。其中在胁迫结束当天056852品系穗部光合处理与对照相差无几，JM22处理穗部光合略微下降，与对照相比不显著，XM26和GC8901处理与对照相比，穗部光合减少显著。胁迫结束后5天，各品种处理与对照的差异越来越大，依照差异大小排列依次为XM26、CG8901、JM22、056852品系。至胁迫结束后第10天，由于生育进程的递进，各品种处理与对照穗部光合都降低，JM22和056852品系的对照均高于胁迫处理，但差异都不显著；XM26和GC8901两品种胁迫处理的穗部光合已经检测不到，而对照穗部仍有光合。高温胁迫处理不仅降低了穗部光合，而且大大缩短了XM26和GC8901的穗部光合持续时间。4、高温胁迫对耐热性不同小麦不同绿色器官光合酶活性的影响研究高温胁迫后冬小麦不同绿色器官的RUBP羧化酶活性都降低，其中与对照相比旗叶的RUBPCase活性降低最为显著。RUBPCase活性降低比较大的是旗叶鞘，变幅仅低于旗叶，变化趋势与旗叶一致。变化最小的是穗部。穗下节间的RUBPCase活性变化基本与穗部表现一致。PEP羧化酶在冬小麦各个绿色器官内的活性水平不一样，穗下节间和穗部的PEP羧化酶活性最高，其次是旗叶鞘，旗叶的PEP羧化酶活性最低，大约只有穗下节间和穗部的50%左右。研究发现高温胁迫使得冬小麦不同绿色器官PEP羧化酶活性与各自对照相比都升高，即胁迫结束时各器官的PEP羧化酶活性都高于其对照处理，说明PEP羧化酶活性在一定温度范围内随着温度的升高而升高。但是在胁迫结束后第5天至第10天，对照处理的PEP羧化酶活性高于胁迫处理。高温胁迫对穗下节间的PEP羧化酶活性影响最小，并且穗下节间PEP羧化酶活性在试验期间变化也最为缓和。旗叶PEP羧化酶活性下降最为剧烈。穗部与旗叶鞘内PEP活性变化程度居于旗叶和穗下节间之间。品种间RUBPCase活性和PEPCase活性受高温胁迫的影响表现一致，但XM26各绿色器官的RUBPCase和PEPCase活性在胁迫后不同时期均低于JM22同期的RUBPCase和PEPCase活性，表现出其不耐热的特点，这是XM26不同绿色器官光合功能下降大于JM22的另一原因。5、高温胁迫对冬小麦不同绿色器官荧光特性的影响研究高温胁迫后不同绿色器官的FV/FM与对照相比，都显著降低。高温胁迫对穗部的FV/FM影响最大，其次是旗叶和旗叶鞘，对穗下节间的FV/FM影响相对最小。两个品种均是如此，不同的是XM26个绿色器官胁迫处理与对照FV/FM的减幅大于对应JM22的各个绿色光合器官。高温胁迫显著提高了JM22和XM26不同绿色器官的F0。不同耐热性品种不同绿色器官F0对热胁迫的反应表现一致，变幅最大的是穗部，其次是穗下节旗叶鞘，然后是旗叶，变幅最小的是穗下节间。品种之间比较发现，XM26各绿色器官F0的变幅均大于JM22，表现出其不耐热的特性。高温胁迫减小了不同绿色器官光系统活性反应中心的开放程度（QP）。与对照相比，开放程度减小最多的是旗叶，其次是旗叶鞘，再次是穗部，最后是穗下节间。高温胁迫降低了旗叶、穗部、穗下节以及旗叶鞘等绿色器官的实时量子产额（QY）。QY受高温胁迫影响最大的是冬小麦的穗部，XM26穗部QY比对照降低5.06%，JM22降低4.88%。实时量子产额受影响较小的是旗叶和旗叶鞘，穗下节间QY受高温胁迫变化最小。品种间比较发现XM26的QY和QP降低较大，既是XM26光合速率下降较大的原因之一，也是XM26为避免过剩光能伤害而进行的一种自我保护。6、不同绿色器官应对灌浆期高温胁迫的耐热避热生理机制研究高温胁迫后，旗叶SOD和CAT活性都显著升高，胁迫结束0天时，JM22旗叶SOD活性较对照升高15.55%，CAT活性增加13.00%。XM26的SOD活性较对照升高22.60%，CAT活性增加增加34.40%。高温胁迫降低了穗部、穗下节间和旗叶鞘的SOD活性和CAT活性。两个品种表现一致，JM22穗部SOD活性下降12.67%，CAT活性下降30.09%，XM26穗部SOD活性下降23.00%，CAT活性降低30.09%。高温胁迫虽然使穗下节间SOD和CAT活性降低，但与各自对照相比差异不显著。高温胁迫后旗叶鞘的SOD和CAT活性比对照略微降低，JM22处理与对照间差异不显著，而XM26的SOD和CAT活性则都与对照差异达显著水平。高温胁迫使旗叶、穗部、穗下节间和旗叶鞘的POD活性不论是在胁迫结束后0天还是胁迫结束后第5天都显著低于对照。高温胁迫后，JM22旗叶的类胡萝卜素显著含量升高，比对照增加9.28%；而XM26旗叶的类胡萝卜素含量显著降低，比对照减少7.77%。高温使两个品种穗部和穗下节间的类胡萝卜素含量都升高，JM22和XM26穗器官类胡萝卜素含量分别比各自对照增多6.20%和7.29%，穗下节间类胡萝卜素含量增多3.46%和4.26%。高温使两个品种旗叶鞘的类胡萝卜素含量都降低，JM22和XM26分别比各自对照减少4.20%和8.99%。高温胁迫后小麦不同绿色器官依赖叶黄素的热耗散能力均增强。依赖叶黄素循环的热耗散能力依次为穗下节间＞穗部＞旗叶鞘＞旗叶。品种间比较发现，JM22依赖叶黄素循环的热耗散能力大于XM26。穗部和穗下节间的非光化学耗散能力较强，而旗叶和旗叶鞘的非光化学耗散能力较弱。高温胁迫后各绿色器官的过剩光能与对照相比都显著降低。与对照相比，过剩光能减小幅度由大到小依次为穗部＞旗叶＞穗下节间＞旗叶鞘。7、高温胁迫对不同绿色器官叶绿体超微结构变化的影响研究高温胁迫使不同耐热性品种旗叶、芒、穗下节间的细胞超微结构都发生了变化，最为显著的影响就是膜结构的破坏，叶绿体，线粒体，细胞核的膜都发生了明显的改变。高温下叶绿体膜结构的变化程度可以作为耐热性与否的鉴定指标。高温胁迫对穗下节间叶绿体的结构程度小于对旗叶叶肉细胞的叶绿体超微结的改变程度。JM22的耐热性要优于XM26，因为热胁迫对JM22各细胞超微结构的损伤程度低于XM26。更多还原

【Abstract】 Wheat (Triticum) is the third crop planted in our country. Yield of winter wheat is about90%of the total wheat yield of our country. Wheat production occupies an important place inour national economy. Recently, heat stress caused by global warming has become morefrequent and severe, which can bring risks to food security. Non-foliar green organs, such asears have photosynthesis performance still in an adverse condition. No-foliar green organscan supply the deficiencies of grain-filling due to green leaves area reducing during latergrowth. Tapping the photosynthesis potential of non-foliar can become a good way forpushing yield limitation and realizing high yield and tolerance-resistance. Studying thephotosynthetic performance and contributions to yield of wheat non-foliar in adverseconditions is very important and can give theories on population structure regulating for ahigh and more stable yield.Four different heat-resistance winter wheat varieties-Jimai22(JM22), Xinmai26(XM26),056852series(056852) and Gaocheng8901(GC8901) were selected as plantmaterials. Effect of high temperature on different green organs and yield formation in wheatduring grain-filling was systematically studied. Photosynthetic performance, heat resistanceperformance of different green organs and contributions to grain yield were preliminarilyclarified. The main results were as follows.1. Studies on contributions of different green organs to grain yieldBy clipping leaves, wrapping ears and wrapping stems and sheaths, the contributions ofdifferent green organs to grain yield were studied at anthesis. The results showed that ears hadthe largest contribution to grain yield with a contribution ratio of41.15%-47.36%. The secondlarger contributor were leaves, with35.98%-43.89%ratio; then were the storage matter instems and sheath; the contributions of exposed peduncle and flag leaf sheath photosyntheticproduct were still small in last place. We also found that different heat-resistance varietiesshowed consistent trend on contribution of different green organs to grain yield.Wheat flag leaves and ears were respectively fed with13C. The results showed that theratio of13C to total C in ears was the highest, either the fed objects were ears or flag leaves;secondly was in stems and sheaths; thirdly was in leaves and the last was in glumes.Comparing the results between treatments of ears fed and of flag leaves fed, we found thatphotosynthesis products in glumes, kernels and leaves from13C fed to ears were more thanthose fed to flag leaves. That is to say, photosynthetic efficiency of ears was higher than thatof flag leaves. 2. Studies on effect of high temperature to yield formation of different heat–resistancevarieties in wheatHigh temperature stress caused different heat-resistance varieties changed at differentlevels in plant morphology. Changes of NDVI valve could reflect the changes of wheat plantmorphology. There were no significant difference in JM22and056852series after hightemperature stress. Yet significant difference happened in NDVI values of XM26and GC8901after stress. As growth times went on, the both latter have more notable difference comparedwith their respective contrasts. High temperature stress accelerated the process of wheatsenescence.The grain-filling duration of different heat resistant varieties was shortened under hightemperature stress and the largest grain-filling ratio was advanced. Heat stress also decreasedthe largest grain-filling ratio of different heat-resistance varieties. The smallest reduction ofgrain-filling ratio was that of056852series, and the second was that of JM22, and the thirdwas that of GC8901, and the largest was that of XM26.High temperature decreased the1000-kernel weight of wheat, which resulted in thedecrease of grain yield. The order of1000-kernel weight change after high temperature wasXM26>GC8901>056852series>JM22by size. Grain yield change was consistent with1000-kernel weight change. The yield reductions of XM26and GC8901were more, reducing11.43%and10.05%compared with their respective contrast. While JM22and056852serieshad less yield reduction, with6.41%and6.93%, respectively.3. Effects of high temperature on photosynthesis enzymes of different green organs inwheat.RuBPCase activates of all different green organs decreased after high temperature stress.Among of the green organs, RuBPCase activities of flag leaves decreased the most. Thedifference between stress treatments and contrasts continued to increase after heat stressending. RuBPCase activities of stressed leaves were significantly lower than those ofcontrasts until to the days after high temperature stress ending. Changes of RuBPCaseactivities in flag leaf sheaths decreased relatively more and had same trend with that of in flagleaves. RuBPCase activities in ears changed the least. Small changes happened in earsRuBPCase from the stress ending day to5thday after stress ending. There were nosignificance between stress treatments and contrasts. Change trends of RuBPCase activities inexposed peduncles were fundamentally same as those in ears. Unlike with those in ears,RuBPCase activities in exposed peduncles were still higher on10thday after stress ending.RuBPCase activities differed not only among different green organs but also between varieties. Drop of RuBPCase activities in XM26green organs was more than that in JM22,which was one of the reasons that caused photosynthetic ability decrease more than that ofJM22.PEPCase activities in different green organs of wheat differed. PEPCase activities inexposed peduncles and in ears were highest; the second highest PEPCase activities were inflag leaf sheaths. PEPCase activities in flag leaves were the lowest, with only50%of those inexposed peduncles and in ears. PEPCase activities increased after high temperature stress.PEPCase activities in all green organs were higher than those in contrasts at stress ending day.But PEPCase activities in contrasts were more than those in stress treatments at5thday and10thday after stress ending. High temperature stress had the smallest effect on PEPCaseactivities in exposed peduncles which changed moderately during the whole experience.There were most drastic changes in flag leaves PEPCase activities: it increased slightly at thestress ending day and then dramatically reduced at5thday after stress ending. There were verylow PEPCase activities in peduncles at10thday after stress ending day. Change extent ofPEPCase activities in ears and in sheaths was in between that of flag leaves and of exposedpeduncles.PEPCase activities not decreased but increase in the conditions of this experiment, whichproved that PEPCase activity increased with temperature rising within certain temperaturelimition.4. Effect of high temperature on photosynthetic rate of different green organsThe general trend in the Pn response to high temperature stress was similar between bothcultivars, while it differed between cultivars in the magnitude of change. Under non-stressedconditions, the Pn in the flag leaves of both cultivars declined steadily from DAS to DES. Incontrast, the Pn in the stressed leaves of both cultivars decreased linearly over time and thedifferences between cultivars were more pronounced under conditions of high temperaturestress. Compared with their respective non-stressed treatments, the Pn of JM22had decreasedby about6.6%at DES and59%at10DAS; however, for the heat-sensitive cultivar XM26,the Pn declined by12.8%at DES and69.9%at10DAS. These results indicate that hightemperature stress accelerated the decline process, showing an inhibition of photosynthesis byhigh temperatures. Conversely, heat stress significantly increased Gs by7.09%for JM22and23.67%for XM26, compared with their respective controls. Nevertheless, Gs declined afterDES. At10DAS, the stomatal conductance for flag leaves of XM26was significantly lowerthan that at DBS. Transpiration showed the same tendency as stomatal conductance. Hightemperature stress had a minor effect on Ci that was associated with the decline in Pn and the drastic changes in Gs and Tr. No obvious changes in Ci were measured during theexperimental period. Except at10DAS, the Ci of leaves was much higher for XM26understress than that without stress due to the acceleration of senescence by high temperaturestress.From the analysis of gas exchange parameters, we concluded that the inhibition ofhigh temperature stress on Pn was not the result of stomata closing, but rather non-stomatallimitation. Furthermore, the decline in Pn from high temperature stress wascultivar-dependent, which was exemplified by the larger variation of Pn in XM26comparedto JM22.Photosynthetic performance of ears in all varieties declined with different degrees. Therewas little difference on photosynthetic ability of ears in056852series between stresstreatments and contrasts. Photosynthetic rate decreased a little between stress and contrast.There were significant differences on photosynthetic rate of XM26and GC8901, comparedwith their respective contrasts. Differences of photosynthetic rate between stresses andcontrasts in the four varieties became more significant at5thday after high temperature stressending. The turn of photosynthetic rate in the four varieties wasXM26>GC8901>JM22>056852by order of difference size.5. Effect of high temperature on fluorescence characteristic of different green organs inwheat.F0of both varieties were significantly enhanced by high temperature. Response of F0tohigh temperature in different green organs and in varieties was consistent. Increase extent ofF0in ears was the most, then in flag leaf sheaths, and then in flag leaves, the least increaseextent in exposed peduncles. XM26showed sensitive to heat, for all of its green organs had alarger increase in F0than JM22.Qp, the closing degree of PSII reaction center, was expanded by high temperature. Thelargest closing degree of reaction center was in flag leaves, and then in flag leaf sheaths, andthen in ears, the smallest in exposed peduncles. Qp in XM26different green organs was largerthan that in each organs of JM22. High temperature decreased QY, the timely quantity yield,of different green organs. The largest effect of QYwas in ears, with a9.33%decrease inXM26and8.86%in JM22, and then in flag leaves and flag leaf sheaths, with a6%-7%decrease in XM26and5%-6%inJM22, the slightest effect of high temperature on F0inexposed peduncles, with a6.41%decrease in XM26and only3.75%in JM22. Fromcomparison between varieties, we concluded that larger decrease degree in QYand QPwasboth one of the reasons photosynthetic performance declined and a self-protection way that XM26avoided harm from excess light energy.6. Physiological mechanism on heat resistance of different green organs to hightemperature stress at grain-fillingHigh temperature accelerated the accumulation of MDA in different green organs.Heat-resistant variety and heat-sensitive variety showed a same trend, with different changedegree. The increase percent to contrast in flag leaves, ears, exposed peduncles and flag leafsheaths of JM22was5.44%,19.11%,3.00%and61.21%, respectively. The increase percentto contrast in corresponding organs was49.55%,15.17%,12.39%and70.46%, respectively.SOD activities and CAT activities in flag leaves increased after high temperature. Atstress ending day, Increase of SOD activities and CAT activities was15.55%and13.00%inJM22flag leaves,22.60%and34.40%in XM26, respectively. Yet high temperature decreasedSOD activities and CAT activities in ears, exposed peduncles and flag leaf sheaths. SODactivities and CAT activities in both varieties ears decreased significantly, with a decrease of12.67%SOD activities and30.09%CAT activities in JM22ears, with a decrease of23.00%SOD activities and30.09%CAT activities in XM26ears. Although there were decreases inpeduncle and flag leaf sheath SOD and CAT activities, there was no significance betweenstress and contrast.POD activities in all green organs declined significantly after high temperature stress,compared with the contrasts. Decreases percent of POD activities in flag leaves, ears, exposedpeduncles and flag leaf sheaths were21.41%,34.97%,36.17%and40.29%in JM22and28.73%,47.04%,46.89%and50.25%in XM26.High temperature had different effect on caroteinoid content in different green organs.Caroteinoid content in JM22flag leaves increased significantly, with a increase of9.28%.However, Caroteinoid content in XM26flag leaves decreased significantly, with a decrease of7.77%. High temperature increased caroteinoid of ears and exposed peduncles in bothvarieties.Caroteinoid content in JM22and XM26ears increased6.20%and7.27%, compared withtheir contrasts,3.46%and4.26%increase percent was in JM22and XM26exposed peduncles,respectively. High temperature stress decreased caroteinoid content in both varieties flag leafsheaths,4.20%decrease in JM22and8.99%decrease in XM26.Heat dissipation capability of different green organs depended on xantophyll cycleenhanced after high temperature. Heat dissipation capability of different green organs wasordered by (A+Z）/（V+A+Z）value, that was exposed peduncle＞ears＞flag leaf sheaths ＞flag leaves. Heat dissipation ability of JM22was greater than that of XM26.Non-photochemical heat dissipation capability was different in different greenphotosynthetic organs. Ears and exposed peduncles had better non-photochemical heatdissipation, while flag leaves and flag leaf sheaths had worse ones. Excessively light energyin different green organs decreased significantly after high temperature, compared withcontrasts. Differences order of different green organs between stress treatments and contrastswere ears, flag leaves, exposed peduncles and flag leaf sheaths.7. Effect of high temperature on ultra-structure of different green organsUltra-structures of different green organs were alerted by high temperature stress.Disruption of membrane structure was the most significant effect. Membranes of chlorophyll,mitochondria and nucleus changes visibly. From the comparison of chlorophyll changesamong awns, exposed peduncles and flag leaves, we found that high temperature stress hadlargest effect on awns chlorophyll structure, larger effect on exposed peduncle chlorophyllstructure and smallest effect on flag leaf chlorophyll structure. JM22showed better heatresistance than XM26, for injury level of JM22from high temperature stress was lesser thanthat of XM26.更多还原