【作者】 叶玉秀；

【导师】 陆卫平；

【作者基本信息】 扬州大学 ， 作物栽培学与耕作学， 2021， 博士

【摘要】 为探明水分胁迫影响糯玉米籽粒产量的生理机制,试验于2014～2015年以国家南方糯玉米区域试验对照品种苏玉糯5号和渝糯7号为材料,研究了不同时期[开花期(抽雄-吐丝)、籽粒建成期(授粉后1-15 d)]水分胁迫(干旱或渍水)对糯玉米产量形成的影响,并从物质积累及转运、抗氧化系统、内源激素、光合作用、碳氮代谢相关酶活性方面分析了其影响产量形成的生理机制。主要结论如下:1产量及物质积累与转运开花期和籽粒建成期水分胁迫降低了糯玉米每穗粒数和粒重,进而降低产量。苏玉糯5号的籽粒产量在开花期干旱(DW1)、开花期渍水(WW1)、籽粒建成期干旱(DW2)和籽粒建成期渍水(WW2)下分别降低了 15.15%、20.17%、27.35%和35.52%;渝糯7号分别降低了 11.95%、15.97%、21.70%和30.26%,表明渍水对糯玉米籽粒产量的影响程度大于干旱,且籽粒建成期水分胁迫对产量的影响程度大于开花期。不同时期水分胁迫均降低了籽粒干重,而籽粒含水量在DW1、DW2和WW1下均显著降低,WW2处理下籽粒含水量21 DAP前高于对照,21 DAP后低于对照,表明灌浆进程受抑。水分胁迫显著增加了糯玉米花前营养器官转运率和花前营养器官转运量对籽粒产量贡献率,降低了花后营养器官同化物转运量、花后营养器官同化物对籽粒产量贡献率以及花后干物质积累量,表明水分胁迫条件下产量对花前营养物质转运量的依赖性增强。2光合荧光特性水分胁迫(干旱或渍水)降低了叶片含水量、气孔导度(Gs)、蒸腾速率(Tr)、光化学猝灭系数(qP),抑制了叶片光合速率(Pn)、实际光化学效率(ΦPSⅡ)、PSⅡ光化学效率(Fv/Fm),提高了叶片胞间CO2浓度(Ci),增加了叶片非光化学猝灭系数(NPQ),渍水对光合参数的影响程度大于干旱,且水分胁迫对苏玉糯5号的影响大于渝糯7号,表明苏玉糯5号对水分胁迫更加敏感。不同时期水分胁迫表明,籽粒建成期水分胁迫对各指标的影响程度大于开花期。复水后,各指标均能得到不同程度恢复,其中开花期水分胁迫下的各指标基本能恢复到CK水平。相关分析表明,产量与Pn、Tr、Ch1 a、Ch1 b以及Car呈极显著正相关,而水分胁迫降低了叶片的Pn、NPQ以及光合色素等光合参数,增加了 Ci,进而影响糯玉米物质生产过程。3抗氧化酶和渗透调节物质水分胁迫提高了叶片和籽粒中超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性和O2-的产生速率,增加了叶片中可溶性蛋白、丙二醛(MDA)、脯氨酸(Pro)和可溶性糖含量。水分胁迫对强势粒的影响小于弱势粒,而渍水对抗氧化酶活性和渗透调节物质的影响程度大于干旱,从而能更有效的清除活性氧,减轻细胞膜损伤。相关分析表明产量与蛋白质含量、可溶性糖含量、SOD、POD和CAT活性呈显著正相关,与MDA、Pro、O2-含量呈显著负相关。4内源激素干旱或渍水增加了叶片和籽粒中脱落酸(ABA)含量,提高了乙烯释放速率(ETH),降低了赤霉素(GA3)、玉米素和玉米素核苷(Z+ZR)和3-吲哚乙酸(IAA)的含量,水分胁迫对强势粒的影响程度小于弱势粒。籽粒建成期水分胁迫对各指标的影响程度大于开花期。复水后,各指标均能得到不同程度的恢复,其中开花期水分胁迫下的各指标基本能恢复到CK水平。水分胁迫对苏玉糯5号的影响程度显著大于渝糯7号,表明苏玉糯5号对水分更加敏感。相关分析表明,产量与叶片、籽粒中ABA、IAA及Z+ZR含量呈极显著正相关,与GA3和ETH含量呈极显著负相关。结果表明水分胁迫下较低的GA3、Z+ZR以及IAA含量和较高的ETH释放速率可能是粒重下降的重要原因。5碳氮代谢相关酶籽粒中ADPG焦磷酸化酶(AGP)活性、可溶性淀粉合成酶(SSS)活性、叶片和籽粒中蔗糖含量、蔗糖磷酸合成酶(SPS)活性、蔗糖合酶(合成方向)活性、谷氨酸合酶(GOGAT)活性、谷氨酰胺合成酶(GS)活性以及蔗糖合酶(分解方向)活性随着灌浆进程先升后降。叶片中淀粉含量、AGP活性、叶片和籽粒中蛋白质含量和硝酸还原酶(NR)活性随着灌浆进程逐渐下降。籽粒中淀粉含量随着灌浆进程逐渐上升。干旱或渍水使叶片和籽粒中淀粉、蔗糖和蛋白质含量减少,且渍水的下降幅度大于干旱;干旱或渍水显著降低了淀粉合成相关酶、氮代谢相关酶、SPS、以及蔗糖合酶(合成方向)活性,提高了蔗糖合酶(分解方向)活性,影响以9 DAP时最大,且渍水影响程度显著大于干旱,籽粒建成期的影响程度大于开花期。复水后,各指标均能得到不同程度的恢复,其中开花期各指标基本能恢复到CK水平,而籽粒建成期水分胁迫处理在复水后14 d仍然恢复不到CK水平,表明籽粒建成期水分胁迫对植株造成了不可逆的伤害。相关分析表明,产量与叶片和籽粒淀粉含量、蔗糖含量、NR、GS、GOGAT、SPS、AGP、SSS以及SBE酶活性呈显著或极显著正相关。这表明较高的淀粉合成相关酶活性及蔗糖合成相关酶活性有利于籽粒中营养物质的积累,进而提高产量。更多还原

【Abstract】 In order to explore the physiological mechanism of water stress affects on the grain yield of waxy maize,the pot trial was conducted at pot farm in 2014-2015.The hybrids were Suyunuo 5 and Yunuo 7,the control varieties of waxy maize national regional trials in Southern China.The water stress(drought or waterlogging)was imposed on flowering stage(tasseling to silking stage)and grain formation stage(about 15 days after pollination).The biomass accumulation and translocation,antioxidant system,phytohormones,photosynthesis,enzymatic activities that involved in the grain yield formation were studied.The main results are as follows.1 Grain yield and biomass accumulation and translocationThe grain number and weight were reduced by water stress at flowering stage and grain formation stage,which induced the grain yield loss.The grain yield loss at DW1(drought at flowering stage),WW1(waterlogging at flowering stage),DW2(drought at grain formation stage),and WW2(waterlogging at grain formation stage)was 15.15%,20.17%,27.35%,and 35.52%in Suyunuo 5,and was 11.95%,15.97%,21.70%,and 30.26%in Yunuo 7.This indicated that the decrease was serious under waterlogging than under drought,and plants were sensitive to water stress at grain formation stage.The grain dry weight was reduced by water stress at different stages.The grain water content was significantly decreased by DW1,DW2,and WW1,which under WW2 treatment was higher than the control before 21 DAP,whereas it was lower than the control after 21 DAP,indicated that the grain filling were suppressed under waterlogging.Water stress increased the rate of remobilization of pre-anthesis stored biomass in vegetative organs and contribution of pre-anthesis stored biomass to grain yield,while amount of remobilization of post-anthesis stored biomass in vegetative organs,contribution of post-anthesis photoassimilate to grain yield,and post-anthesis biomass accumulation were decreased.This indicated that the grain yield under water stress conditions was mainly dependent on pre-anthesis stored photoassimilates.2 The photosynthetic and fluorescentic charactersWater stress(drought or waterlogging)reduced leaf moisture content,stomatal conductance(Gs),transpiration rate(Tr),photochemical quenching coefficient(qP),inhibited leaf photosynthesis rate(Pn),actual photochemical efficiency(ΦPSII)and PSII photochemical efficiency(Fv/Fm),meanwhile increased intercellular CO2 concentration(Ci)and non-photochemical quenching coefficient(NPQ),the effect of waterlogging on photosynthetic parameters was greater than that of drought,and the effect of water stress on Suyunuo 5 was greater than that of Yunuo 7,which indicated that Suyunuo 5 was more sensitive to water stress.The result showed that the effect of water stress at grain formation stage on leaf photosynthetic and fluorescentic characters were higher than it imposed on flowering stage.After re-hydration,all indexes could be recovered to different degrees,and the plants that suffered water stress at flowering stage can recovered to control level.The results of correlation analysis showed that the grain yield was positively correlated with Pn,Tr,Chl a,Chl b and Car.However,water stress decreased the photosynthetic parameters such as Pn,NPQ and photosynthetic pigments in leaves,increased the concentration of Ci,and led to the grain yield loss.3 Antioxidant enzymes and osmotic regulatorsWater stress enhanced the activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)and production rate of O2-,and increased the contents of soluble protein,malondialdehyde(MDA),proline and soluble sugar in leaves and grains.The superior grain was less affected to water stress than that of the inferior grain.The activities of antioxidases and osmotic regulation substances were more sensitive to waterlogging than to drought,which can remove reactive oxygen more effectively,reduce the damage degree of cell membrane.Correlation analysis showed that the yield was significantly positively correlated with the contents of protein and soluble sugar,and the activities of SOD,POD and CAT,and negatively correlated with MDA,Pro,and O2-.4 Endogenous hormoneWaterlogging or drought stresses increased the content of ABA and ETH produce rate but decreased the content of GA3,Z+ZR and IAA in leaves and grains.And the inferior grains were more sensitive to water stress than that of superior grains.The influence of water stress at grain formation stage on plant endogenous hormones were severe than that of stress imposed at flowering stage.After re-watering,the parameters can recovered at a certain level,and the plant that had suffered water stress at flowering stage can recovered to control level.The effect of water treatment on Suyunuo 5 was significantly greater than that on Yunuo 7,which indicated that Suyunuo 5 was more sensitive to water stress.The results of correlation analysis showed that the yield was positively correlated with the contents of ABA,IAA and Z+ZR,and negatively correlated with the contents of GA3 and ETH in leaves and grains.Therefore,lower contents of GA3,Z+ZR and IAA and higher release rate of ETH under water stresses were the important reasons for the decrease of grain weight.5 Enzymes related to carbon and nitrogen metabolismWith plant growth,the activity of ADP-glucose pyrophosphorylase(AGPase)-and soluble starch synthase(SSS)in grains,sucrose phosphate synthase(SPS),sucrose synthetase(synthetic),glutamate synthase,glutamine synthetase,sucrose synthetase(cleavage)and sucrose content in leaves and grains increased first and decreased later.Meanwhile,starch content and AGP activity in leaves as well as nitrate reductase(NR)activity and protein content in leaves and grains decreased with grain filling,while starch content gradually increased.Drought or waterlogging reduced the contents of starch,sucrose and protein in leaves and grains,and the decrease was higher when plants suffered waterlogging.Drought and waterlogging significantly reduced the enzymatic activities related to starch synthesis,nitrogen metabolism,SPS and sucrose synthase(synthetic),but increased the activity of sucrose synthase(cleavage).The influence was highest at 9 DAP.Moreover,the effect of waterlogging on plants was significantly greater than that of drought stress.Plants were more sensitive water stress that imposed on grain formation stage than imposed on flowering stage.After rewatering,all indexes could be recovered to a certain degree,and the plants suffered water stress at flowering stage can recovered similar to the control level,while those suffered stress at grain formation stage could not recovered to the control level after 14 days of rewatering,and the recovery of waterlogging was less than that of drought,which indicated that water stress caused irreversible damage to plants.The results of correlation results indicated that the yield was positively correlated to the contents of starch,sucrose,activities of NR,GS,GOGAT,SPS,AGP,SSS and SBE in leaves and grains,which indicated that higher enzymatic activities related to starch sucrose synthesis were beneficial to increase nutrients and then improve grain yield in waxy maize production.更多还原