Photosynthetic Characteristics Of Different Raspberry Cultivars

The raspberry（Rubus corchorifolius L.f）,a perennial semi-shrubby fruit tree of the genus（Rubus）in the family（Rosaceae）,is native to Eurasia and America.Raspberry fruit is soft and juicy,rich in sugar,organic acids,vitamin C,amino acids,anthocyanins and other nutrients,loved by consumers.Raspberry fruit can not only be eaten fresh,but also processed into raspberry cans,jams,drinks and other food,has become one of the main cultivated berry fruit trees in China.To investigate the photosynthetic characteristics of different raspberry varieties,this study took three raspberry varieties,’Triple Crown’blackberry,’Veramis’red berry and’Hertz’red berry,as the main research objects.The daily changes of photosynthetic parameters and chlorophyll fluorescence parameters as well as the effects of different sodium metasilicate on chlorophyll fluorescence parameters of raspberry leaves were studied in order to provide a theoretical basis for the selection of good varieties of raspberry cultivation,selection of high-quality seedlings and scientific cultivation management in our province.The results of the study are as follows:1.The photosynthetic parameters and physiological parameters of three raspberry varieties,’Triple Crown’blackberry,’Veramy’red plum and’Heltz’red plum,were measured using a LI-6400 portable photosynthesis meter.The daily variation of photosynthetic parameters and physiological factors of the three raspberry cultivars was measured.The daily changes in net photosynthetic rate（Pn）of the three raspberry varieties were bimodal,with peaks at about 12:00 and 15:00,respectively,and the net photosynthetic rate of’Triple Crown’blackberry was higher than that of’Veramis’redberry and’Heltz’redberry.The peak net photosynthetic rate of’Triple Crown’blackberry was only 65%of that of’Triple Crown’blackberry;transpiration of’Triple Crown’blackberry leaves was higher than that of’Veramis’and’Heltz’blackberry,and the peak value of’Heltz’blackberry was only 65%of that of’Triple Crown’blackberry.The transpiration rate of’Triple Crown’blackberry leaves is relatively low compared to the other two raspberry varieties,and water loss is relatively low,making it more resistant to drought than the other two raspberries;the intercellular carbon dioxide concentration（Ci）of’Hertz’red berry is the highest,followed by’Triple Crown’Triple Crown’blackberry had the highest intercellular CO₂concentration（Ci）,’Triple Crown’blackberry the second highest and’Veramy’redberry the lowest;’Triple Crown’blackberry had the highest mean value of water use efficiency（WUE）,’Veramy’redberry in the middle and’Helterzee’cranberry the smallest.Therefore,’Triple Crown’blackberry has higher net photosynthetic rate（Pn）,stomatal conductance（Gs）and water use efficiency（WUE）and lower transpiration rate（Tr）,and is better adapted to the local ecological environment compared to other raspberry varieties.2.The chlorophyll fluorescence parameters of’Triple Crown’blackberry,’Veramis’red berry and’Hertz’red berry were measured using a YAXIN-1161G chlorophyll fluorescence meter.The daily variation of chlorophyll fluorescence parameters of three raspberry species was measured by a fluorometer.The results showed that the photochemical efficiency（Fv/Fm）,maximum fluorescence（Fm）and immediate maximum fluorescence（Fm’）of raspberry showed a trend of decreasing and then increasing under sunny weather from 8:00 am to 18:00 pm,while the electron transfer rate（ETR）,photosynthetically active radiation（PAR）and non-photochemical quenching coefficient（qN）showed a trend of increasing and then decreasing.The trend of Fm’and Fv’was that they were not increasing.From the Fm’and Fv/Fm curves,it can be seen that’Triple Crown’blackberry appears to be relatively lightly photoinhibited and can accept strong light irradiation and can be grown in strong light environments.The ETR and qN curves show that their trends are consistent with the changes in light intensity,with the ETR values of’Triple Crown’blackberries being larger than those of’Veramy’cranberries and’Hertz’This indicates that’Triple Crown’blackberries have a strong photorespiratory capacity,higher light energy use efficiency and less heat dissipation,ensuring that the absorbed light is This means that the absorbed light energy can enter the electron transport system and thus carbon fixation to the greatest extent possible.3.The effect of sodium metasilicate on chlorophyll fluorescence parameters of three raspberry leaves was measured using a YAXIN-1161G chlorophyll fluorometer.The results showed that the initial fluorescence（Fo）,maximum fluorescence（Fm）,fluorescence value under activated light（Fs）,fluorescence intensity measured at 2 ms（FJ）,fluorescence intensity measured at 30 ms（FI）,PSII photometric efficiency（Yield）,photochemical efficiency（Fv/Fm）,photochemical quenching coefficient（qP）),non-photochemical quenching coefficient（qN）,actual photochemical rate（ΦPSII）,minimum fluorescence in light（Fo’）,immediate maximum fluorescence（Fm’）and electron transfer rate（ETR）all showed a rising then decreasing or always decreasing trend with increasing sodium metasilicate concentration from 8:00am to11:00am trend.