干旱胁迫下外源钙对石灰岩地区复羽叶栾树种子萌发的影响

Effects of exogenous Ca^(2+) on the seed germination of Koelreuteria paniculata in limestone area of Southwest China under drought stress.

以石灰岩生态恢复优选树种复羽叶栾树种子为试材,采用聚乙二醇(PEG6000)设置0%(CK)、5%、15%、25%、30%模拟石灰岩山区不同干旱环境,以CaCl_2设置0(CK)、15、20、25、30 mmol·L^(-1)为外源钙离子梯度,模拟石灰岩地区的土壤高钙环境,研究不同浓度CaCl_2、PEG及二者交互作用对种子萌发特征的影响.结果表明:单纯CaCl_2作用下,中低浓度的外源钙对复羽叶栾树种子萌发参数无显著影响,而高浓度的外源钙对种子萌发具有抑制作用,中低浓度CaCl_2可以增加萌发后幼苗的鲜质量.PEG浓度从0%增至25%,各处理组的种子发芽率、发芽势、发芽指数及活力指数均与对照呈显著递减趋势,幼苗鲜质量明显减小.对各干旱处理组施加一定浓度的外源钙后,中低浓度的CaCl_2可提高种子的萌发特性,而当CaCl_2浓度达到30 mmol·L^(-1)时,种子难以萌发.PEG浓度达到30%时,种子无萌发.施加一定的外源钙可以提高PEG胁迫下幼苗的鲜质量,使幼苗更加适应干旱缺水的环境.

In this paper, different arid environments in the limestone area of Southwest China were simulated by using different concentrations （0%, 5%, 15% , 25% , and 30% ） of PEG6000 （po- lyethylene glycol）, and a gradient of exogenous Ca2＋（0, 15, 20, 25, and 30 mmol · L-1 of CaC12） was installed to simulate the high calcium soil environments, aimed to study the effects of different concentration PEG6000, CaCla, and their interactions on the seed germination characteristics of Koelreuteria bipinnata, one of the preferred species in the ecological restoration in limestone area. Under the action of CaC12 alone, medium or low concentration exogenous Ca2＋ had lesser effect on the seed germination parameters, but high concentration exogenous Ca2＋ had inhibition effect on the seed germination. Medium or low concentration CaC12 could increase the seedling fresh biomass. When the PEG6000 concentration increased from 0% to 25% , the seed germination rate, germina- tion potential, germination index, and vigor index showed a significant decreasing trend, and the seedling fresh biomass decreased remarkably. When certain concentration of exogenous Ca2＋ was ex- erted to the drought treatment groups, medium or low concentration CaC12 improved the seed germi- nation characteristics, which compensated the loss from drought stress to a certain degree. When the CaC12 concentration was up to 30 mmol · L-1, the seeds were hard to germinate. Additionally, no seeds germinated under the condition of PEG with the concentration of 30%. It was suggested that applying definite concentration of exogenous Ca2＋ could increase the seedling fresh biomass under PEG6000 stress, and make the seedlings more adapt to arid environment.