Photosynthetic and physiological responses of 9 camellia cultivars to high temperature stress and comprehensive evaluation of heat tolerance
[Objective]The heat tolerance of Camellia attracts more attention due to its rich flower types and colors and long flowering period.Suitable evaluation methods and indexes can provide bases for the heat-tolerance identification,the discovery of heat-tolerance germplasm,and the breeding of new cultivars of Camellia.[Methods]C.uraku and'Wirlinga Cascade'were used as reference materials,and 7 new cultivars of cluster-flowering camellia were selected as test materials.They were cut in vase.After short-term(5 h)or long-term(7 d)high-temperature(42 ℃/35 ℃)treatment,changes of morphological and photosynthetic indexes were investigated and heat tolerance was evaluated comprehensively.[Results](1)The contents of chlorophyll,carotenoid,and chlorophyll a/b,net photosynthetic rate(Pn),and stomatal conductance(Gs)of'Chuizhi Fenyu'and'Wirlinga Cascade'were increased.Their maximum photo-chemical efficiency of PS Ⅱ(Fv/Fm),potential activity of PS Ⅱ(Fv/Fo),and electron transport rate(ETR)were remained at a high level.Additionally,they did not show signs of heat damage after 7 days of high temperatures.Pn and Gs of'Jinye Fenyu','Shangzhi Huazhang',and'Meigui Chun'were de-creased significantly under high temperature stress,while intercellular CO2 concentration(Ci)was in-creased.Among them,the Fv/Fm,Fv/F.,and ETR of'Jinye Fenyu'and'Shangzhi Huazhang'were significantly reduced.After 7 days of long-term high temperature stress,these 3 cultivars showed severe heat damage or became dead.(2)15 individual indicators were converted into 4 independent comprehensive indicators with cumulative contribution rate of 90％through principal component analysis.The compre-hensive weight values of chlorophyll content,carotenoid content,and xanthophyll content were higher at 5 h under high temperature stress,and the comprehensive weight values of chlorophyll a/b,Fv/Fm,photo-chemical quenching coefficient(qP),and non-photochemical quenching coefficient(qN)were higher at 7 d under high temperature stress.[Conclusion]According to the comprehensive evaluation value D,'Chuizhi Fenyu'is a heat-tolerance cultivar,'Shangzhi Yueguangqu','Shangzhi Huanlesong',and'Sweet Gem'are moderate tolerance,and'Meigui Chun','Shangzhi Huazhang',and'Jinye Fenyu'are the weakest among the new cultivars of cluster-flowering camellia.Chlorophyll,carotenoid,and xanthophyll contents can be used as the key indicators to analyze the short-term high temperature stress,while chlorophyll a/b,Fv/Fm,qP,and qN can be used as the key indicators to analyze the long-term high temperature stress of Camellia.
cluster-flowering camelliahigh temperature stressphotosynthetic pigmentsgas exchange parameterschlorophyll fluorescence parameterscomprehensive evaluation
NETL
NSTL
万方数据
维普
