Studies On Photosynthetic Physiological Characteristics And Fruit Yield And Quality Of Three Types Of Jujube Trees In Northern Shaanxi

In this paper,three jujube varieties in northern Shaanxi were studied.From May to October 2020,the German GFS-3000 portable photosynthesis instrument was used to measure the leaf development,flowering and fruit setting,fruit expansion and fruit maturity of the three jujube varieties.Key indicators such as environmental factors,net photosynthetic rate（Pn）,stomatal conductance（Gs）,transpiration rate（Tr）,etc.were studied and analyzed for three jujube tree varieties in northern Shaanxi during the leaf development period,flowering and fruit setting period,and fruit expansion.The relationship between photosynthetic physiological characteristics and ecological factors during the fruit ripening period;comparing the fruit quality of Li Jujube,You Jujube and Goutou Jujube by indoor measurement and analyzing and evaluating the correlation with the physiological factors during the fruit ripening period,the final result is that the fruit Physiological factors that have a greater impact on yield and quality.The main findings are as follows:（1）In the four phenological periods,the Pn of the three jujube tree varieties showed a"double peak"change curve,and the"noon break"phenomenon was more obvious;The peak is higher than the afternoon peak.The Pn change trend is different in different phenological periods.Among them,the Pn value gradually increases in the leaf spreading period,flowering and fruit setting period,and fruit swelling period,but the fruit maturity period shows a downward trend.Different types of jujube trees have different phenological periods,and the daily maximum and daily average values of Pn are all:You jujube>Goutou Jujube>Li jujube.The photosynthetic efficiency of Jujube is higher than the other two lines.The change trend of Gs and Pn is consistent.（2）The CO₂ response curves of the three jujube varieties from the leaf development stage,the flowering and fruit setting stage,the fruit expansion stage to the fruit maturity stage are relatively close.Under the light intensity of 1200μmol·m^-2·s^-1,the Pn prophase varies As the CO₂ concentration increases,it remains relatively stable after a certain degree,but the LCP and LSP values are different.On the whole,the leaf spreading period,flowering fruit setting period,and fruit swelling period gradually increase,and the fruit maturity period becomes smaller.Indicating that the first three phenological periods have strong ability to use light intensity.（3）The WUE of the 3 jujube varieties in different phenological periods showed a trend of first high and then low,and the leaf spreading period and fruit maturity period were relatively small,and the flowering and fruit setting period and fruit swelling period were relatively large.Growth is relatively slow during the period,with little water demand,and weak dry matter synthesis ability.At the same time,with the growth and development of crops,WUE will gradually increase and reach its peak.In the later stage of crop growth,it will decrease due to the weakening of photosynthetic capacity of crop leaves.The highest value of WUE in the four phenological periods of the 3 jujube species all appeared at 9:00.The daily average value of Jujube was the largest,followed by Goutou Jujube,and the smallest Li Jujube,indicating that Jujube has a stronger ability to use water resources and is suitable for drought.Planted in the region.（4）The net photosynthetic rate Pn of the three jujube cultivars during the fruit expansion period was tested with environmental factors and physiological factors,respectively,to conduct a bilateral Pearson coefficient test.The results showed that the three jujube varieties had little correlation with environmental factors and physiological factors in different phenological stages.The main factors affecting Pn in the four phenological stages of jujube are PAR,Gs,Tr,and Ci.（5）Through the comparison of the yield and quality of the 3 jujube varieties,it was found that the appearance evaluation of Li Jujube was the highest,and the You Jujube was the lowest;the taste of Goutou jujube was the best,followed by Li Jujube and You Jujube.Correlation analysis found that Pn has a linear relationship with the yield of the three jujube varieties.The R² value of Jujube is 0.9608,which is the largest;Pn and Vc have a non-linear relationship.The R² value of Goutou Jujube is 0.9762,which is the largest;Pn and total sugar are linear.Relationship,the R² value of Goutou jujube is0.9752,which is the largest.The growth cycle of You and Goutou Jujube is longer than that of Li Jujube.The yield of You Jujube and Goutou jujube is higher than that of Li Jujube.The net photosynthetic rate Pn and WUE of Li Jujube are lower,while the net photosynthetic rate Pn and WUE of You Jujube and Goutou jujube are higher and more drought tolerant.Therefore,You Jujube and Goutou jujube are more suitable for cultivation and growth in Jiaxian County.