Study On The Foliage Growth And Photosynthetic Fluorecence Characters Of Differernt Germplasm Resources Of Peach Varieties Of Four Growth Types

The growth types of peaches are divided into four kinds,including common,weeping,broom and dwarf type.Physiological characteristic is one of the important photosynthetic traits of plants,the research of fruit tree photosynthesis is of great importance for production cultivation of fruit trees.In recent years,the portable photosynthetic measurement system and chlorophyll fluorescence analysis system are becoming more and more popular,people begin to have some research on photosynthetic characteristics in peach varieties of different growth types,but little study on photosynthetic physiological characteristics for the whole year growth stages.The materials of this study is the leaves of four growth types peach trees,analysed the growth index,diurnal variation of photosynthetic parameters,gas exchange parameters and chlorophyll fluorescence parameters on peach trees in late May(late spring and early summer),early August(summer)and early October(autumn).The results showed that:(1)Among the three periods,leaves of most types in late May and early August were larger than those in early October,and the growth length,width and leaf area of the common type were larger,the broom type was the lowest,and the different branches of same growth type showed a decreasing trend from long branches to short branches;the specific leaf weight of most types of peaches in early October was higher than that of late May and early August,among the different growth types,the broom type was higher,and the weeping type was lowest.The plant height of common type was hightest in three periods,and the crown and ground diameter were significantly smaller than those of other growth types,the crown of common type was larger than other types.The dwarf type was the largest in early August and early October,and it was slightly smaller than the common type in late May,the plant height and crown of weeping type were between common type and dwarf type.The leaf aera coefficient of different growth types showed a trend of rising first and then descending in different periods,and the leaf aera coefficient in early October was smaller than that in late May,The leaf area coefficient of the broom type was significantly larger than that of other growth types in three periods.The internode length of the common type was significantly larger than that of other types.The length of the dwarf type was the lowest,presented extremely short,and the branching angle of dwarf type was the highest.(2)Among the photo synthetic ability of different growth types,the dwarf type was the highest,followed by the common type,weeping type was the lowest;Among different growth types,the WUE of common type was the highest,and that of broom type was the lowest,that the blade thickness and stomatal density of broom type were lower than other varieties may have a relationship with it,the diurnal variations of water use efficiency(WUE)was a“W" type curve in late May and a "U" type curve in early August,the curve in early October is a broken line.The WUE in late May was the highest,the difference between early August and early October was little;The photo synthetic ability of dwarf type,weeping type and broom peach showed the following variation:late May>early August>early October,and the normal type for:late May>early October>early August,In the same growth type,the photosynthetic ability of long branches is generally higher than middle branches and short branches.The diurnal change of Pn showed a unimodal curve in late May and early October,but it showed a bimodal curve in early August and has a "midday depression" at noon,which caused by stomatal limitation and nostomatal factors.Throughout the growing season,the photosynthetic active radiation(PAR),stomatal conductance(Gs)and transpiration rate(Tr)were very important to the diurnal change of Pn among the physiological and ecological factors.(3)The Pn of most growth types showed a decreasing trend from late May to early October,and the Pn of dwarf type was the largest among different growth types.The transpiration rate(Tr)was higher in early August than that in late May and early October.The water use efficiency(WUE)of most types was the highest in late May,and the same growth type showed a tendency of increase gradually from long branches to short branches.The intercellular CO2 concentration(Ci)of each growth type was of little difference in three periods,and the Ci in early October was slightly larger than that in late May and early August.The light compensation points(LCP)of different growth types decreased in early October,in the same growth type,there was a decereasing trend from long branches to short branches among different branches.The light saturation points(LSP)of each type were presented a "low-high-low"trend in different periods,the LSP of common type was higher,the(AQY)of most growth types decreased in different degrees in early August and rebounded in early October.In early August,the CE of weeping type and broom type were significantly higher than that in late May and early October,and the difference between common and dwarf type was not obvious among different periods.The Co2 compensation points ofeach growh type were between 81.30 and 91.17 ?molm.-2.s-1.The photorespiration rate of most types showed a downward trend from late May to early October.(4)Diurnal variations of chlorophyll fluorescence remain relatively stable in late May;under high temperature and strong light in early August,the diurnal variations of Fm was a"V" type curve,and the Fv/Fm of different growth type was reduced in different degree,among different growth types,the Fv/Fm,ETR of broom type was the highest,followed by the common type,the dwarf type was the lowest.The Fv/Fm,ETR and qP in early October were lower than those in early October and early August.The leaf pigment content in early August was the highest,and that in early October was the lowest.Among the four growth types,the common type and dwarf type were the highest,and the broom type was the lowest.Correlation analysis showed,the correlation coefficient of Ta and PAR with ?PS?,qP,ETR reached extremely significant level,the correlation coefficient of Fm,Fv/Fm,ETR with photo synthetic pigments were relatively higher.