Effect Of GA₃ On Photosynthesis And Hormone In Leaves Of Brumal Jujube (Zizyphus Jujube Cv. Dongzao)

In this experiment, the effect of different concentrations of gibberellin on photosynthesis and endogenous hormone of Dongzao leaves in florescence were studied. And analysed the levels of chlorophyll, solubility sugar, starch, protein and endogenous hormone of leaves.Combinated the measurement of specifice weight and area of leaves .researched how the exogenous gibberellin effected physiological and biochemical changes on photosynthesis of Dongzao leaves in florescence. And then provide theoretical basis and practical guidanc for the use of gibberellin on Dongzao cultivation.1. Using different concentrations of gibberellin on Dongzao leaves had not changed the type of photosynthesis rate change. The processing factors all presented typical double-peak curve, and obvious 'midday depress' phenomenon.The peak values occurred at about 10:00 and 14.00 respectively.The first peak value was higher than the second peak value.The main reasons for the midday depression were stomatal and non-stomatal factors, 20mg/L, 40mg/L and 60mg/L gibberellin treatments reduced the decrease of Photosynthesis rate at the midday depression, but 80mg/L gibberellin treatments increased the drop.2. Different concentrations of gibberellin affected the stomatal conductance and intercellular concentra -tion. The improment of photosynthesis was resulted from stomatal conductance ascending and intercellular concentration descending under 20mg/L and 40mg/L gibberellin treatments.Photosynthetic rates increased 100.28% and 109.45% at about 10:00, 40mg/L treatment was higher than that of control. But stomatal conductance descended and intercellular concentration ascended under 60mg/L and 80mg/L gibberellin treatments,so the photosynthesis was declined. And the negative effects of 80mg/L was more visible than 60mg/L treatment.So the main reasons for gibberellin affecting photosynthesis of Dongzao leaves were stomatal and non-stomatal factors.3. After the handed of gibberellin ,the light compensation was improved in addition to the 80mg/L treatment, which 40mg/L was more visible.Light saturation point was reduced by all the treatments.and 40mg/L was more visible than the others.4. 40mg/L gibberellin treatment had a positive effect on chlorophyll content of Dongzao leaves. And the effect was the most obvious after 5 days. 20mg/L treatment was similar with the control, 60mg/L and 80mg/L had a negative effects on chlorophyll content . All the gibberellin treatment reduced the value of chlorophyll a/b.5. Although solubility sugar content rised after reducing , the overall trend was downward. And the decline margin was 40mg/L>20mg/L>CK >60mg/L>80mg/L,the 35th day compared with the first day.Starch content was reduced at the first 1 to 14 days, and then rised rapidly, at the 35th day starch content was higher notable than the first day. Protein synthesis was promoted by gibberellin, but did not change the trend of changes of the protein content. 7 days after treatment, protein content reached the highest, and the 40mg/L gibberellin treatment was higher than the others.6. Gibberellin treatment of 40mg/L and 20mg/L played a important role in boosting Dongzao leaves leaf area growth, and 40mg/L had very significant differences. On the contrary ,60mg/L and 80mg/L processing reduced the leaf area growth and margins, 80mg/L gibberellin treatment had the most obvious effect. As far as the effect of gibberellin on the spedfice weight was concerned ,the effect was not apparent, and after had be processed 1-7 days, 40mg/L treatment was higher than other contrast, but the difference was not significant. 80mg/L treatment was less than contrast ,and the difference was not significant too. After different degree of drop ,all treatments were similar deal with the contrast ultimately.7. Gibberellin treatment had not changed endogenous hormone content trends of Dongzao leaves ,with overall downward trend for IAA, ZR, GA₃, ABA. Compared with the contrast all treatments increased the endogenous hormone levels, and the improve margin was 80>60>40>20 mg/L.8. Exogenous gibberellin addressed valid for 14 days or so. In the concentration processing, 40mg/L treatment had the best results of promotion on photosynthesis, and with the most obvious effect after 5 days or so in dealing.