Study On Leaf Morphological Structure And Photosynthetic Characteristics Of Wild European Plum

Wild European plum（Prunus dometica L.）,commonly known as wild plum,Rosaceae,Prunus plants.This species was first discovered in 1982.Due to human disturbance,difficulties in self-breeding and other factors,the population size of this species was narrow and broken,making wild European plum in Xinjiang endangered.Leaf is the largest photosynthetic organ in plants.Studying leaf structure and photosynthetic characteristics can understand its me Tab.olic process and play an important role in transplanting and protection.Therefore,in this study,Li-6400XT photosynthetic apparatus,FM pulse modulated fluorescence apparatus and paraffin section method were used to measure the relevant indicators of different tree ages and different months in different distribution areas of wild European plum,to study the photosynthetic fluorescence and leaf morphological structure differences and seasonal dynamic changes in different distribution areas,and to provide a theoretical basis for the protection of wild European plum.The main research results are as follows:（1）The comparison of morphological structure of wild European plum leaves showed that the drought resistance of wild European plum was weak.Compared with the original distribution,the leaves of transplanted wild European plum showed obvious drought resistance characteristics,that is,leaf area,leaf stem narrowing,and more slender leaf shape.Leaf blade structure arranged more closely than native distribution.The upper epidermis,palisade tissue,spongy tissue,lower epidermis and leaf thickness of wild European plum were less than those of native distribution.The upper epidermis and leaf thickness of wild European plum gradually increased with the change of month.The net photosynthetic rate（P_n）of wild European plum was significantly positively correlated with leaf thickness,significantly correlated with upper epidermis thickness,palisade tissue thickness,and palisade-sea ratio,and significantly negatively correlated with leaf porosity.Leaf thickness was the index of leaf morphological structure that had the greatest impact on Pn of wild European plum.（2）The diurnal variation curve of Pn of wild European plum was’bimodal’,and the photosynthetic midday depression factor was stomatal limitation factor;the diurnal variation curves of transpiration rate（T_r）,stomatal conductance（G_s）and stomatal limitation（L_s）were’bimodal’;the diurnal variation curve of water use efficiency（WUE）and intercellular CO₂concentration（C_i）showed a trend of’decrease-increase’.The photosynthetic capacity of wild European plum is relatively weak.Pn is negatively correlated with tree age,positively correlated with physiological factors G_s,negatively correlated with C_i,and positively correlated with environmental factors C_aand PAR,which may be one of the endangered factors of wild European plum.（3）Wild European plum had obvious photoinhibition at noon,and the damage to PSII reaction center was reversible.With the decrease of light intensity and temperature,the function of photosynthetic organs gradually recovered.Wild European plums natively distributed better adapted to strong light environments.With the increase of tree age,the heat dissipation capacity of wild European plum decreased,and the electron capture efficiency decreased gradually under strong light.The photosynthetic activity of wild cherry plum was significantly higher than that of wild European plum.The chlorophyll fluorescence parameters affecting P_nof wild European plum were photochemical quenching coefficient（q P）,non-photochemical quenching value（NPQ）,and initial fluorescence（F_o）,and the direct influence order was q P>F_o>NPQ.q P had the greatest indirect promoting effect on Pn of wild P.europaea by inhibiting NPQ.