【作者】 郭晓冬；

【导师】 邹志荣；

【作者基本信息】 西北农林科技大学 ， 蔬菜学， 2008， 博士

【摘要】 本试验以辣椒（Capsicum annuum Linn．）为试材，利用人工气候箱模拟日光温室冬季生产中常见的低温弱光环境，从辣椒生长形态、光合作用、矿质营养元素吸收、耐冷性指标等方面探讨了辣椒在低温弱光条件下的生长特性及适应机制，旨在为辣椒设施栽培和耐低温弱光育种提供理论依据。试验主要结果如下：1、低温弱光可显著影响辣椒茎的伸长量、茎粗的增长量、及叶面积的增长量；分别在偏低温（昼21～23℃／夜8～10℃），极端低温（昼15～20℃／夜5～6℃）条件下，进一步降低光照，茎的伸长量、茎粗的增长量、及叶面积的增长量差异不显著，而在一定的弱光(150μmol·m^-2·s^-1，100μmol·m^-2·s^-1)下，随着温度的下降，辣椒茎的伸长量、茎粗的增长量、及叶面积的增长量显著降低，说明低温对辣椒茎的伸长、茎粗增长及叶面积增长的抑制作用强于弱光。2、低温弱光环境下，两个参试品种辣椒植株的根系及地上部干物质积累均明显减少，而且地上部变化最为突出。与对照相比，偏低温弱光处理地上部干物质积累量缓慢增长，且随着光照减弱，干物质积累也显著减少；实验结果显示，白天15～20℃、夜间5～6℃是辣椒生长的临界温度，处理7～15天，辣椒干物质积累呈现负增长。若遇到这种气候条件，生产中应尽早采取措施，避免此环境持续超过5～7天，否则辣椒生长将无法恢复。3、低温弱光处理使辣椒植株根系的琥珀酸脱氢酶活性降低。低温弱光处理7天后，在对照条件下恢复生长10d，偏低温弱光处理的植株根系活力可恢复至与对照相同或接近的水平，而极端低温弱光处理的植株根系活力仍很低，表明低温是影响辣椒根系活力的首要限制因子。4、低温弱光显著影响辣椒对矿质营养元素的吸收、运输和分配。研究表明，偏低温弱光及其处理初期，矿质元素从根系向茎、叶的运输减缓，随着温度、光照的逐步降低和处理时间的延长，植株的光合作用及呼吸代谢都受到抑制，矿质元素的吸收明显减弱。陇椒2号在偏低温弱光下，K在辣椒叶片中相对富集、增强了叶片渗透势，这可能是陇椒2号耐低温弱光的机理之一。辣椒在低温弱光下对微量元素的吸收特点是，偏低温较弱光下(21～23℃／8～10℃、150μmol·m^-2·s^-1)，叶片中Fe和Mn的含量高于对照，表明植物自身通过调节营养元素的分配以促进叶绿素的合成，同时呼吸作用增强；其余处理Zn、Mn、Cu、Fe等微量元素在根部积累，说明此时微量元素的吸收、运输受阻。随着低温弱光逆境的持续，叶片的光合、呼吸均显著减弱，对营养元素的吸收显著减少。5、辣椒经低温弱光处理后，光合色素的含量和组成比例发生了明显的变化，并且两个供试辣椒品种有明显差异。陇椒2号耐低温弱光的能力较佳木斯强，在低温弱光处理初期，其叶绿素含量及其组成比例的变化均小于佳木斯，而且在偏低温弱光下，其对弱光的适应性调节能力较强；而佳木斯在处理初期叶片的叶绿素含量即随温度降低而有显著变化，叶绿素b含量急剧下降导致chla／b比值显著提高，说明在低温弱光下chlb被破坏，叶片的光合作用受到抑制。低温弱光下辣椒的光合参数均显著降低。两个供试辣椒品种之间的光合特性略有差异，佳木斯对低温弱光的反应比陇椒2号敏感，尤其随光照降低，其光合作用显著降低。6、低温弱光胁迫下，辣椒叶片的相对电导率和丙二醛含量都有不同程度的提高，在偏低温下，随着光照减弱，相对电导率和丙二醛含量差异不显著；在极端低温下，随着光照进一步减弱，相对电导率和丙二醛含量明显提高，随着处理时间延长，同一温度下，随着光照降低，叶片丙二醛含量也显著增加，由此可初步判断，低温是导致细胞膜脂过氧化的直接原因。7、经偏低温较弱光(21～23℃／8～10℃、150μmol·m^-2·s^-1)处理后，辣椒叶片的超氧化物歧化酶（SOD）活性变化与对照无显著差异，但随着温度、光强的逐步降低和处理时间的延长，SOD、POD活性显著降低。8、在偏低温较弱光下，辣椒能积累更多的脯氨酸，增强渗透调节，减轻低温冷害。随着温度的降低、光照的减弱及处理时间的延长，辣椒叶片可溶性糖含量显著下降且下降幅度依次增大；笔者认为，可溶性糖是光合作用产物的重要组成分，低温弱光处理已显著阻碍了光和产物的合成及运输，因此，可溶性糖和可溶性蛋白不宜作为测定辣椒幼苗耐冷性的指标。9、试验还通过外源Ca²⁺及Ca²⁺信号抑制剂对低温下辣椒幼苗生理指标的影响，验证了Ca²⁺信号系统参与了调节辣椒幼苗抗寒过程中渗透调节物质的合成。更多还原

【Abstract】 This study was conducted in phytotron which modeled lower temperature and poor lightoccurred often in solar greenhouse in winter production.Growth morphology,photosynthesis,absorption of nutrient and chilling tolerance index of pepper（Capsicum annuum Linn.）werestudied under lower temperature and poor light condition to reveal its growth characteristicand acclimation mechanism.The purpose of this study was to provide theoretical basis forprotected cultivation and breeding for tolerance for lower temperature and poor light ofpepper.The results show as follows:1.Elongation and augment of stem as well as increase of leaf area were affectedsignificantly under lower temperature and poor light.Under suboptimal temperature（day21-23℃/night 8-10℃）and lower temperature（day 15-20℃/night 5-6℃）,there was nosignificant difference in elongation and augment of stem as well as increase of leaf area withdecreasing light intensity,while under poor light(150μmol·m^-2·s^-1,100μmol.m^-2·s^-1),theywere decreased significantly with decreasing temperature.2.Under lower temperature and poor light condition,dry mass accumulation of shootand root of two varieties declined dramatically especially of shoot.Dry mass accumulation ofshoot increased slowly under suboptimal temperature and poor light(21-23℃/8-10℃;150μmol·m^-2·s^-1,100μmol·m^-2·s^-1)compared to control,and it also decreased significantlywith poorer light;the results show that critical temperature of pepper growth were15-20℃and 5-6℃in day and night respectively.Dry mass accumulation decreased after 7-15d treatment.So counter measures should be used early to avoid such climate conditionexceeding 5-7d,or the growth of pepper would not recover.3.Succinic dehydrogenase activity decreased under lower temperature and poor lightcondition.After 7 d lower temperature and poor light treatment and then grown 10 d undercontrol condition,root activity of plants treated by suboptimal temperature and poor light(21-23℃/8-10℃;150μmol·m^-2·s^-1,100μmol·m^-2·s^-1)recovered to about level of control,but itwas still very lower in plants treated by low temperature and poor light(15-20℃/5-6℃;150μmol·m^-2·s^-1,100μmol·m^-2·s^-1),which show that lower temperature was primary factoraffected root activity. 4.Low temperature and poor light significantly affected absorption,transportation andallocation of nutrients of pepper plants.The results show that in early stage of suboptimaltemperature and poor light,transportation of mineral elements from root to shoot and leafdecreased,photosynthesis and respiration of plants were inhibited with decreasingtemperature and light as well as treatment time which resulted in dramatic decline ofabsorption of mineral elements.K enriched in leaves of Longjiao No.2 under lowtemperature and poor light which could increase osmotic regulation,this maybe thetolerancemechanism to low temperature and poor light of Longjiao No.2.With respect to absorption of micro-nutrients of pepper,Fe and Mn were higher thancontrol under suboptimal temperature and lower light(21～23℃/8～10℃、150μmol·m^-2·s^-1),which indicate that plant could regulate allocation of nutrients by itself to synthesischlorophyll and increase respiration;Zn,Mn,Cu,Fe etc.micro-nutrients accumulated in rootunder other treatments,i.e.transportation of micro-nutrients were inhibited.Photosynthesisand respiration of leaves declined and absorption of nutrients reduced significantly withlonger treatment.5.Photosynthesis pigment content and component ratio were altered by low temperatureand poor light treatments and there were significant difference between two varieties.Longjiao No.2 can tolerate low temperature and poor light more than Jiamusi as itschlorophyll content and ratio changed less than that of Jiamusi as well as its strongerregulation capacity.On the country,chlorophyll content of Jiamusi changed dramatically withdecreasing temperature,chlb declined rapidly resulted in increasing chla/b which indicatesdamage of chlb and inhibition of photosynthesis.Photosynthesis parameters were declinedremarkably under low temperature and poor light.There was a little difference betweenphotosynthesis characteristic of the two varieties,response of Jiamusi to low temperature andpoor light was more sensitive than that of Longjiao No.2 and decreased pronouncedly withdecreasing light.6.EC and MDA of pepper leaves increased under low temperature and poor light,therewere no significant differences between them with decreasing light at 21-23℃/8-10℃,butthey were increased dramatically at 15-20℃/5-6℃.So we can speculate that lowertemperature was the direct reason resulted in cell membrane lipid peroxidation.7.No significant difference of SOD activity was observed under suboptimal temperatureand poor light(21-23℃/8-10℃;150μmol·m^-2·s^-1),but SOD and POD activity substantiallydeclined with lowering temperature and light as well as treatment time.8.Under suboptimal temperature and lower light,proline accumulated to increaseosmotic regulation capacity and alleviate chilling damage.Soluble carbohydrate of pepper leaves decreased progressively and significantly with decreasing temperature and lightintensity as well as longer treatment time.So we think that synthesis and transport ofphotosynthetic product were inhibited by low temperature and poor light as solublecarbohydrate was important component of photosynthetic product.Thus,soluble carbohydrateand protein were not suitable to be used as index of chilling tolerance of pepper seedling.9.Effects of different concentrations of Ca²⁺and inhibitors of Ca²⁺signal system onsome osmolytes,including soluble protein,soluble sugar and proline in pepper under lowtemperature stress were investigated.The results indicated that extraneous calcium（10mmol/L）treatment could markedly increase the content of soluble protein,soluble sugar and proline.Moreover,addition of Ca²⁺chelating agent EGTA or calmodulin antagonist W7 couldmarkedly decrease the content of soluble protein,soluble sugar and proline.Taken togetherthe above results,it is suggested that Ca²⁺signal system may be regulated by change of someosmolytes in Pepper under low temperature.更多还原