不同种类大黄萌发及幼苗内源激素与非结构性碳水化合物对温度与渗透胁迫交互的响应

Responses of seed germination,seedling endogenous hormones and non-structural carbohydrates of differ-ent Rheum species to the interaction of temperature and osmotic stresses

为探讨不同温度下干旱与盐胁迫对3种大黄种子萌发和幼苗生长的影响,以聚乙二醇6000和NaCl分别模拟不同强度的干旱和盐胁迫,纯水处理为对照组(CK),分别置于3种温度(10、20、30℃)的人工气候箱内培养。结果表明:20℃各处理下3种大黄的最终发芽率和发芽势均较高,30℃与干旱或盐的交互胁迫会抑制大黄种子萌发且不成苗;10℃时,随盐胁迫的加剧掌叶大黄地上和地下部分的脱落酸(ABA)含量呈升高趋势;20℃时,随干旱、盐胁迫的加重掌叶大黄地上和地下部分赤霉素(GA)、生长素(IAA)含量均呈降低趋势,且随干旱加剧3种大黄地上/地下非结构性碳水化合物(NSC)呈先降低后升高的趋势;10℃和20℃下,随盐胁迫加剧药用大黄地上GA/地下GA呈先升后降的趋势,地上IAA/地下IAA为先降后升的趋势,而随干旱加剧掌叶大黄和唐古特大黄的地上和地下部分NSC含量呈先增后减的趋势;不同处理下药用大黄的萌发指标低于其他2种大黄,表现为更易受到温度和干旱胁迫的影响;20℃为3种大黄萌发适宜温度,高温会加剧渗透胁迫对大黄种子萌发和幼苗生长的危害而适宜的温度能对渗透胁迫起到一定的缓解作用;大黄通过调节不同部位的可溶性糖和淀粉含量及其比例以保持细胞渗透平衡,通过调整激素含量与分配模式维持生理与代谢活动以缓解逆境危害。

We investigated the effects of drought and salt stresses on seed germination and seedling growth of three Rheum species(rhubarb)at different temperatures(10,20 and 30℃)in an artificial climatic chamber.Polyethy-lene glycol 6000 and NaCl were used to simulate different intensities of drought and salt stresses,respectively,with pure water treatment as the control check(CK).The results showed that total germination percentage and germina-tion potential of the three rhubarb species were higher under each treatment at 20℃.The interaction between 30℃and drought or salt stresses inhibited seed germination and made seedlings failed to establish.At 10℃,the abscisic acid(ABA)content of both aboveground and belowground parts of R.palmatum tended to increase with increasing salt stress.At 20℃,the contents of gibberellin(GA)and auxin(IAA)in both aboveground and belowground parts of R.palmatum tended to decrease with the aggravation of drought and salt stresses.The ratios of aboveground to underground non-structural carbohydrates(NSC)of the three rhubarb species tended to decrease and then in-crease with the aggravation of drought.At 10 and 20℃,the ratios of aboveground to underground GA of R.offici-nale tended to increase and then decrease with increasing salt stress,the ratios of aboveground to underground IAA tended to decrease and then increase with increasing salt stress,while the NSC content of both aboveground and be-lowground parts of R.palmatum and R.tanguticum tended to increase and then decrease with drought exacerbation.The germination index of R.officinale under different treatments was lower than that of the other two species and showed greater susceptibility to temperature and drought stresses.20℃was the appropriate temperature for the ger-mination of the three species.Higher temperature could exacerbate the harmful effects of osmotic stress on seed ger-mination and seedling growth,but the appropriate temperature could play a certain role in alleviating the osmotic stress.The rhubarb maintains cellular osmotic balance by regulating the content of soluble sugars,starch,and their ratios in different parts of the plant,and maintains physiological and metabolic activities by adjusting hormone con-tent and allocation patterns to alleviate adversity hazards.