Study On Growth And Photosynthetic Characteristics Of Hybrid F1 Ornamental Peach Seedlings

Ornamental Peach is an ornamental plant originated from China and it has great potential for landscape application.In recent years,the breeding of new ornamental peach varieties and the regulation of flowering period have been the research hotspot,but the growth and photosynthetic characteristics of hybrid progenies of ornamental peach have been ignored.Photosynthesis provides sufficient material basis for the growth and development of plants and their own value,so it is necessary to study the growth and photosynthetic characteristics of ornamental peach.In this study,five F1 generations of ornamental peaches were used as experimental materials.Five F1 generations are ’Yuanchun’ x’Mantianhong’,’Baihuashanbi’x ’Mantianhong’,Mantian.Hong self pollinateon,’Fenhuashanbi’x ’Jiangtao’ and Jiangtao self pollination.The initials of parents are YM,BM,MM,FJ and JJ respectively.By analyzing and comparing the growth index,photosynthetic parameter,chlorophyll fluorescence parameter,pigment content and leaf anatomical index,the differences of growth and photosynthetic characteristics of five F1 generations were obtained,And try to establish a more scientific way of comprehensive evaluation of photosynthetic performance,It provides theoretical support for the selection of high photosynthetic performance of ornamental peach hybrid progeny,provide basis for the management of ornamental peach seedling.The main conclusions are as follows:(1)The growth rule of five F1 generations:April to July is the peak period of plant height and ground diameter growth,and the growth gradually stops in the middle of July to mid-September;the total growth of FJ plant height is the largest,MM is the smallest;the total growth of ground diameter mm is the largest,YM is the smallest;FJ and JJ tend to grow higher,with fewer branches but longer branches,belonging to the open tree type,YM,BM,MM tend to grow lengthways,with more branches and shorter branches,belonging to the dwarf tree type.(2)Photosynthetic Changes of five F1 generations:In June and September,the diurnal variation curve of PN in five F1 generations was "single peak type",in July and August,there are "single peak" and "double peak" types,BM,FJ and JJ photosynthesis has "noon break" phenomenon,and the net photosynthetic rate in September is the lowest;The diurnal variation of Tr,Gs and Pn is similar,and the diurnal variation of Ci is opposite to that of Pn;the stepwise regression equation of Pn and physiological and ecological factors of five F1 generations shows that Pn is negatively correlated with Ci and RH,and positively correlated with WUE,Tr,Gs,Ca and PAR;the photosynthetic rates of BM and YM of hybrid progeny are higher than that of parent inbred MM,and there is little difference between FJ and JJ.(3)The difference of photosynthetic response of five F1 generations:comparing the characteristic parameters of photosynthetic response of five F1 generations,it is concluded that the photosynthetic potential and light adaptability of YM and BM are stronger than that of their parents MM,and there is little difference between FJ and JJ.(4)Analysis of chlorophyll fluorescence parameters of five F1 generations:the differences of varieties of each index are very small;Fv/Fm is more than 0.75,indicating that the growth of five F1 generations is not affected by the stress environment;the distribution of light energy of five F1 generations is Y(Ⅱ)accounting for 50%,Y(NPQ)accounting for 30%,Y(NO)accounting for 20%;Y(Ⅱ)is negatively correlated with Y(NPQ),NPQ,indicating that the more excitation energy is used for heat dissipation,the less it is used for photochemical reaction,Fv/Fm.There is a positive correlation between Y(Ⅱ)and ETR,indicating that the electron transfer efficiency and the maximum photochemical efficiency of PSII are directly proportional to the formation of photosynthetic capacity.(5)Pigment changes and differences of five F1 generations:the pigment content was higher in July,the lowest in August and the lowest in September;Correlation analysis shows that Chla and Chlt of five F1 generations are positively correlated with Pn;The Chlt content of the leaves of YM and BM is higher than that of the parents MM,and FJ is lower than JJ,the hybrid YM and BM may have better photosynthetic performance than parent(MM),but FJ has worse photosynthetic performance than parent JJ.(6)The differences of leaf structure among five F1 generations are as follows:JJ has the largest index of mesophyll structure and BM had the largest index of main vein structure;Ds is positively correlated with TMV,VA and XA,indicating that the more stomata in leaves,the more developed transport system;Pn is positively correlated with TMV,VA,XA,TP,Ds,HVPD,TRPS and DCTR,indicating that leaf structure had a great influence on photosynthesis.(7)Comprehensive analysis of photosynthetic performance:the weights of indicators are obtained by principal component analysis,and the values of subordinate functions of indicators are weighted to get the measurement values.The sum of the measurement values of each indicator is five F1 generation of comprehensive measurement values of photosynthetic performance,which are sorted by size as:JJ>FJ>YM>BM>MM.Based on the above analysis,April to July is the growth peak of five F1 generation seedlings,so should pay attention to strengthen the water and fertilizer management;July and August are prone to the phenomenon of photosynthetic noon break,which needs to be frequently sprinkled to the ground air to create a microclimate to alleviate;the hybrid progenies YM and BM show better light adaptability than their parents(MM),which has a wider range of application and is not suitable for shade in the cultivation process,and there is no difference between FJ and JJ,JJ and FJ have the strongest photosynthetic performance and the fastest growth.They can be used as excellent plants for cultivation and subsequent observation of ornamental properties.