【作者】 郑楠；

【导师】 艾希珍；

【作者基本信息】 山东农业大学 ， 蔬菜学， 2009， 硕士

【摘要】 本试验以‘富根卫士’‘部野丁’为砧木,以‘赤峰特选甜椒’为接穗,研究甜椒自根苗(CK)、砧木苗(WO、BO)和嫁接苗(WG、BG)的根系特性,嫁接对甜椒幼苗耐冷的影响及其耐冷机理。结果表明1.砧木苗和嫁接苗的根系总长度、重量、体积、根尖数、表面积及根系活力均显著高于自根苗。低温胁迫可使以上指标明显降低,但降低幅度多以WO和WG最小,BO和BG其次,CK的降低幅度最大。将幼苗置常温下恢复5 d后,根系总长度、重量、体积、根尖数和表面积等多未达到胁迫前水平,但根系活力显著增强。2.低温胁迫3 d时,甜椒幼苗叶片的光合速率(Pn)、气孔导度(Gs)、和羧化效率(CE)均下降50%以上,之后Pn、Gs趋于平稳,CE持续下降;胞间CO2浓度(Ci)呈先下降,后上升趋势。低温条件下,甜椒幼苗的暗下最大光化学效率(Fv/Fm)、光下实际光化学效率(ФPSⅡ)及电子传递速率(ETR)显著降低,初始荧光(Fo)有所升高,表明其光合结构受到一定的伤害,但处理结束3 d后基本恢复。与自根苗相比,嫁接苗在各处理阶段的Pn、Gs、CE、ФPSⅡ、Fv/Fm和ETR都有不同程度的提高,Fo明显降低。可见,嫁接可显著提高甜椒幼苗的光合功能,减轻低温对其光合作用的影响。3.甜椒嫁接苗与自根苗叶片可检测到的脂肪酸种类多于根系;低温胁迫可使甜椒幼苗的不饱和脂肪酸的相对含量升高,胁迫前、胁迫后和恢复后,嫁接苗的不饱和脂肪酸相对含量均高于自根苗。4.低温胁迫5 d后,嫁接苗和自根苗叶片中的IAA、GA3含量及根系中GA3含量明显降低,而ABA含量有所升高;嫁接苗叶片胁迫前后的IAA、GA3和ABA含量及根系中的GA3和ABA均高于自根苗, GA3 / ABA比值显著低于自根苗。较低的GA3/ ABA比值是嫁接苗耐冷性提高的内在原因之一。5.随着低温胁迫时间的延长,甜椒幼苗的APX、GR活性先升高,后降低。常温下恢复3 d后,APX和GR活性均达到胁迫前水平。嫁接苗在各处理阶段的APX和GR活性显著高于自根苗的,两个嫁接苗相比,WG显著高于BG。可见,嫁接可通过保持较高的抗氧化酶活性,提高活性氧清除能力减轻低温对甜椒幼苗的伤害。6.甜椒幼苗的水势和渗透势随着胁迫时间的延长而降低,5 d后快速回升,可溶性糖和脯氨酸含量随着低温胁迫时间的延长而升高。常温下恢复3 d,甜椒幼苗的水势和渗透势持续升高,但未达到胁迫前水平,而可溶性糖和脯氨酸含量先降低,后升高,3 d后显著高于胁迫前水平。嫁接苗的水势和渗透势及可溶性糖与脯氨酸含量多显著高于自根苗,两个嫁接苗相比,WG显著高于BG。嫁接苗的渗透调节物质含量升高是其耐冷性增强的又一重要原因。更多还原

【Abstract】 The root characteristics of‘Chifengtexuan’own-root seedlings (control, CK),‘Weishi’and‘Buyeding’rootstock seedlings (WO, BO), and graft seedlings which‘Chifengtexuan’scion grafted onto‘Weishi’and‘Buyeding’rootstocks (WG, BG), and graft on mechanism of chilling tolorance in sweet pepper were investigated. The results were as follows.1. The total length, weight, volume, tips, surface area, and activity of roots in rootstock seedlings and graft seedlings were significant higher than those of roots in own-root seedlings. Low temperature stress decreased the above indexes of all seedlings, but the decreasing amplitude of WO and WG showed the least and CK the largest. Returned to normal condition, the root length, weight, volume, tips, total surface area, et al. of sweet peppers mostly failed to the primary level in 5 days except to the root activity.2. Low temperature led to decrease in photosynthetic rate (Pn), stomatal conductance (Gs), and carboxylation efficiency (CE) over 50% in 3 days. Then, the Pn and Gs was tending towards stability, but CE decreased continually.The intercellular CO2 concentration (Ci) declined at first, whereas enhanced at latter four days during stress period. Low temperature and weak light intensity decreased maximal photochemical efficiency of PSⅡin darkness (Fv/Fm), actual photochemical efficiency of PSⅡduring illumination (ФPSⅡ), and electron transport rate (ETR), but increased initial fluorescence (Fo). These implied that low temperature stress caused a damage of photosynthetic apparatus, but the damage recovered in 3 days. Compered with the control, Grafting increased Pn, Gs, CE,ФPSⅡ, and Fv/Fm with various degrees, but decreased Fo after both low temperature stress and recovery. So we conclude that grafting leads to increase in photosynthetic function, and alleviate in the effect of low temperature and light intensity on photosynthesis of sweet pepper seedlings.3. Richer kinds of fatty acid were detected in leaves than in roots of own-root and graft sweet pepper seedlings. Low temperature increased the relative content of unsaturated fatty acids in sweet pepper seedlings. The relative content of unsaturated fatty acids in graft seedlings was higher than that of in own-root seedlings on the eve of stress, after stress, and recovery stage.4. Low temperature decreased IAA and GA3 contents in leaves and GA3 content in roots of sweet pepper seedlings, but increased ABA content. Graft seedlings showed higher contents of IAA, GA3 and ABA in leaves and GA3 and ABA in roots, lower ratio of GA3 and ABA, compared with own-root seedlings. These data suggest that lower ratio of GA3/ABA is one of the important internal causes of the increase in chilling tolerance in graft seedlings of sweet pepper.5. The APX and GR activity increased at first day, whereas decreased at latter six days during stress period, and hadn’t recovery in 3 d under normal condition. Compared with the own- root seedlings, graft seedlings showed higher activity of APX and GR in all treating stages. The APX and GR activity of WG was significant higher than that of BG. These data suggeste that graft alleviate the chilling damage in sweet pepper seedlings by holding higher antioxidation enzymes activity, and improving the eliminating capacity to reactive oxygen species.6. Water potential and osmotic potential of sweet pepper seedlings decreased gradually in the first, but increased 5 d latter. The soluble sugar and proline contents increased as stress time increased. The potential and osmotic potential of sweet pepper seedlings increased continually in recovey days, but hadn’t came to the primary levels in 3 d. The soluble sugar and proline contents decreased at first, while increased afterwards, and were significant higher than those on the eve of stress. Graft seedlings showed higher water potential, osmotic potential, soluble sugar and proline contents compared with own-root seedlings, and those of in WG were higher than in BG. Increase in content of osmoregulation substances is one of the important internal causes of the increase in chilling tolerance in graft seedlings of sweet pepper.更多还原