热锻炼对高温胁迫下2个杜鹃花品种耐热性的影响

Effects of Heat Acclimation on Heat Rresistance of Two Rhododendron Cultivars

以2个杜鹃花品种‘粉珍珠’(Rhododendron‘Fen zhen zhu’)和‘状元红’(Rhododendron‘Zhuang yuan hong’)为材料,经过30℃6 d的热锻炼后,分别在38、42℃高温下胁迫6 d,研究经过热锻炼的2个杜鹃花品种光合作用、叶片解剖结构、渗透调节物质以及抗氧化系统的变化,以期探究热锻炼对不同杜鹃花品种耐热性影响的生理机制。结果表明:热锻炼处理通过气孔导度(G_s)、细胞间隙CO_2摩尔分数(C_i)及蒸腾速率(T_s)的不同变化进而提高2个杜鹃花品种的净光合速率(P_n);热锻炼提高栅栏海绵组织比,保证了叶片组织结构的稳定;热锻炼处理后,2个品种中渗透调节物质可溶性糖、可溶性蛋白、游离脯氨酸(Pro)质量分数均下降;热锻炼处理后,叶片中过氧化氢(H_2O_2)和丙二醛(MDA)质量摩尔浓度下降且差异显著性不同,‘状元红’叶片MDA质量摩尔浓度在38℃高温胁迫下变化显著,这是2个品种中超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性变化差异的结果。这些结果说明,热锻炼处理能提高杜鹃花植株的耐热性,其减轻伤害的机理与植物品种有关。

With the changes in the photosynthesis, anatomy, osmotic regulation substances as well as antioxidant system, we studied the effects of heat acclimation on the thermostability of Rhododendron under heat stress in leaves of two Rhododen- dron cultivars, Rhododendron ＇ Fen zhen zhu＇ and Rhododendron ＇ Zhuang yuan hong＇ , exposed to two heat stress levels （ 38℃ and 42℃ ） for 6 d, after heat acclimation at 30℃ for 6 d. Heat acclimation enhanced P, of two Rhododendron cul- tivars by different changes of Gs, Ci and Ta. Under heat stress, heat acclimation enhanced ratio of palisade to spongy and it ensured anatomy stabilization. Osmotic regulation substances like soluble sugar, soluble protein and free praline were de- clined after heat acclimation in two Rhododendron cuhivars. The decline being significantly different of the molality of H2O2 and MDA after heat acclimation were the results of different changes in SOD, POD and CAT activity in two Rhododendron cuhivars. The molality of MDA changed significantly in the leaves of Rhododendron ＇ Zhuang yuan hong＇. Therefore, heat acclimation can improve thermostability of Rhododendron, and the mechanism of alleviating the damage is related to cuhi-vars.