Study On Colnal Physiological Integration Of Kingdonia Uniflora

Spacial and temporal heterogeneity is a ubiquitous feature of plant habitats,even in a tiny scale.In the evolutionary process,plants may have various adaptive strategies to environmental heterogeneity.However,the physiological plasticity is the most direct response of plants to heterogenous environment.Therefore,strengthen to the research which the physiological plasticity of clonal plants is helpful to more accurate grasping the environmental influence on clonal plants.Guerrilla clonal plant Kingdonia uniflora is distributed the understory of Betula utilis forest(2400-2500 m above sea level),Abies fargesii forest(2800-2900 m a.s.l.)and Larix potaninii var.chinensis forest(3000-3100 m a.s.l.)in Taibai Mountains National Forest Park of Shaanxi Province,China.In this thesis,photosynthetic characteristics of the species,plasticity of physiological and biochemical traits in leaves and nutritive elements allocations characteristics in organs of different ramet ages were researched by employing the method of comparative study the natural populations.The aim of the study was to probe into physiological plasticity of the species,which is the mechanism responded to the heterogeneous environment,and to provide scientific evidences and foundation for the reason of endangered,maintaining mechanism and preserving policy of K.uniflora.The main conclusions are as follows:1.The diurnal change of net photosynthetic rate(Pn)of presented a bimodal pattern,i.e., reaches the maximum at 13:30 and 16:30,and had a midday depression.The diurnal variation patterns of leaf transpiration rate(Tr)and water use efficiency(WUE)were also bimodal.2.The light compensation point(LCP)was 14.93μmol·m^-2·s^-1,and the light saturation point(LSP)was 215.76μmol·m^-2·s^-1,suggesting that K.uniflora could only adapt to restricted light condition.3.Chlorophyll a(Chl a),chlorophyll b(Chl b)and total chlorophyll(Total Chl)contents in leaves of different ramet ages were low in the young ramet of different altitudes,and decreased with rising altitude.Soluble sugar content showed a reverse trend that of Chl a,Chl b and Total Chl.These changes not only protected the young ramet from the strong light radiation and low temperature to adapt the higher altitude surrounding,but also were propitious to successfully accomplish their life process such as photosynthesis.4.Ramet age and altitude had significant effects on nitrate nitrogen(NO₃^--N)and nitrate reductase(NR).Glutamate synthetase(GS)showed a trend similar to that of the proline(Pro)and contrary to that of soluble protein.Soluble protein content was comparative high in the higher altitude,which was help to adapt their growth environment.It was supposed that NO₃^--N accumulated of interconnected ramets was the process of further transforming and forming the protein under the catalysis of NR, GS,and the clonal fragments of K.uniflora could adapt to the heterogenous environments by regulating nitrogen metabolism among the interconnected ramets.At the same time,nitrogen metabolism coordinated with the carbon metabolism to adapt better to living environment of K.uniflora.5.The activities of superoxide dismutase(SOD)and guaiacol peroxidase(POD)were increased with rising altitude,but catalase(CAT)activity was decreased with increasing altitude and ramet age.The reduction of CAT activities could regard as a stress signal to activate other antioxidant defense mechanism.At the higher altitude and the older ramet,the amount of UV-B absorbing compounds increased.The content of glutathione(GSH)was markedly increased with rising altitude(p＜0.05),but there were no significant differences in ascorbate(ASA)content among ramets of different altitude(p＞0.05).6.Ramet age had no significant effect on malondialdehyde(MDA)content(p＞0.05), which was significant difference among altitudes(p＜0.01).At the higher altitude,the content of MDA increased.It was indicated that antioxidant enzymes(SOD,POD, CAT)and antioxidant compounds(GSH,ASA)of clonal fragments coordinated with each other to protect the membrane of interconnected ramets of K.uniflora against major deleterious effects of activated oxygen species.At the higher altitude(3000～ 3100 m),lipid peroxidation levels of leaf increased.It was likely that seriously low temperature and strong solar radiation of the higher altitude had exceeded the anti-oxidant protection ability of the leaf,which the cooperative effect of antioxidant was not enough to totally remove the excessive active oxygen.However,oxidative damage could not up to its intensity of causing death,therefore,their life processes such as photosynthesis could still be finished.7.Ramet age,altitude and their interaction had no significant effects on total-carbon content of leaf,rhizome and root in ramet among K.uniflora(p＞0.05),and had different effects on total-nitrogen,total-phosphorus,potassium and magnesium contents of vegetative organ,respectively.8.Ramet age significantly affected potassium content in vegetative organs and total nitrogen content in rhizome and root of K.uniflora ramet at high-altitude habitat(3 000-3 100 m a.s.l,p＜0.05).9.All nutrient element contents of K.uniflora were correlated with each other at different altitudes except the one at middle altitude(2 800-2 900 m a.s.l.),which showed insignificant correlation between total nitrogen,total phosphorus,magnesium and potassium content of ramet.It was implied that the impact of physiological plasticity on performance of clonal plants from high altitude could be greater than those from low altitude.Powerful physiological plasticity could be helpful for K.uniflora to successfully inhabit higher-altitude habitats by effectively utilizing heterogeneity resources to realize population expansion and open up new habitat.It was likely that physiological plasticity of K.uniflora responding to heterogeneity habitats was formed in its long-term evolvement.