Projecting the potential distribution and analyzing the bioclimatic factors of four Rhododendron subsect.Tsutsusi species under climate warming

Tsutsusi is one of the eight subgenera of the Rhododendron genus.Four Tsutsusi species,R.indicum,R.simisii,R.oldhamii,and R.schlippenbachii,have high ornamental and medicinal values,resulting in an increasing market demand.These species thrive in cool and humid environments and are widely distributed in Europe and Asia.Whether global climate warming will affect the distribution of these valuable resources remains unclear.Thus,this study analyzed the climatic suitability of these species for the first time on the basis of 1552 geographical distribution points and 19 bioclimatic factors using the maximum entropy model.The results show that a suitable distribution area for all four species would decrease under climate warming.The main bioclimatic factors affecting their distribution are the mean temperature of the coldest quarter for R.indicum,the mean diurnal range for R.simisii,and precipitation of the warmest quarter for R.oldhamii and R.schlippenbachii.In addition,the contribution of the temperature-related bioclimatic factors to the distribution of R.indicum and R.simisii is higher than that of the associated precipitation-related climatic factors;in contrast,the contribution of precipitation-related bioclimatic factors to the distribution of R.oldhamii and R.schlippenbachii is higher than that of the temperature-related climatic factors.These results provide references for the introduction,conservation,sustainable development,and utilization of these four species in the future,and may also provide information with regards to other Rhododendron species.

盐胁迫对杜鹃生理生化与叶绿体亚显微结构的影响

以皋月杜鹃(Rhododendron indicum)为材料,采用盆栽试验研究不同浓度盐胁迫对杜鹃花生理生化特征和叶绿体亚显微结构的影响.结果表明:在低盐胁迫下,植株生长健壮,可溶性蛋白质含量、过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性均显著高于对照,叶绿素和丙二醛(MDA)含量增加不显著,叶绿体亚显微结构完好,基粒片层排列整齐,与对照无差异,表明杜鹃可在低NaCl含量的土壤中正常生长;在120 mmol·L-1NaCl溶液处理下,植株叶片开始出现较轻的受害症状,随着盐浓度升高,植株受害症状加重,可溶性蛋白质和叶绿素含量显著下降,而MDA含量显著上升,POD、CAT和SOD活性先升后降,叶绿体结构逐渐膨胀成圆形,空洞化程度渐渐变大,膜慢慢解体,表明杜鹃在一定程度上具有抗盐胁迫的能力;在高盐胁迫下,叶绿体结构和功能被破坏,叶片黄化衰老.

模拟酸雨对3种盆栽灌木幼苗叶矿质元素含量的影响

采用盆栽方法,以3种不同pH值(3.0、4.0、5.0)的模拟酸雨溶液对红木、杜鹃、夏鹃幼苗进行浇灌处理,研究不同pH值的酸雨对幼苗叶矿质元素含量的影响.结果表明:模拟酸雨对3种灌木幼苗叶矿质元素含量均有一定影响,3种幼苗叶中的大多数矿质元素含量变化不一致,表明不同植物的不同元素对酸雨的反应不同;各酸雨处理红木幼苗叶K、Mg、Mn、Ni、S、Al的含量较对照增加,其中Al、Ni含量是随着酸雨pH值的降低而逐渐增加,Zn含量比对照含量有所减少,N、P、Ca、Fe、Cu、Cd、Pb含量不随酸雨pH值的变化而变化,红木幼苗叶Al含量与模拟酸雨的pH值达到显著负相关;3种酸雨处理后的杜鹃幼苗叶P、Cu、Mn、Pb含量均比对照增加,其中P、Cu含量是随酸度的增大而逐渐增加,Ca、Zn含量比对照有所减少,N、K、Mg、S、Al、Fe、Ni、Cd含量没有随着酸度变化而随之变化的趋势,P含量与模拟酸雨的pH值达到显著负相关;3种酸雨处理后的夏鹃幼苗叶P、K、Mg、Al、Fe、Cu、Mn、Ni、Pb含量比对照增加,其中P、Ni是随酸度增加逐渐增加,Zn含量比对照减少,N、Ca、S、Cd含量则表现为有的酸雨处理增加,有的下降,Ni含量与模拟酸雨的pH值达到显著负相关.该项研究可为南方绿化植物的选择提供理论依据.