（1）试验初期，喷施钙剂降低了枣果黑顶病发病率，随着钙浓度的增加，枣黑

(1) At the beginning of the experiment, spraying calcium agent reduced the incidence of black top disease in jujube fruit. With the increase of calcium concentration, the incidence of black top disease in jujube fruit gradually decreased; the activities of three antioxidant enzymes in jujube fruit (SOD, POD) , CAT) After the concentration of Ca1, Ca2, and Ca3 are treated, it gradually increases, and its activity is significantly higher than that of CK treatment. It reached the maximum value at Ca3 and then decreased slightly; the vitamin C content and calcium content of jujube fruit also showed a trend of first increasing and then decreasing, and both reached the optimal value at Ca3. The results indicate that Ca3 can be used as the optimal concentration for preventing and curing black top disease of jujube fruit.

(1) At the beginning of the experiment, the calcium spray reduced the incidence of black-top disease in the fruit, and with the increase of calcium concentration, the incidence of the black-top disease decreased gradually, and the activity of three antioxidant enzymes (SOD, POD, CAT) in the fruit gradually increased after Ca1, Ca2 and Ca3 concentration treatment, and its activity was significantly higher than CK treatment. The maximum value was reached at Ca3, and then decreased slightly, and the vitamin C content and calcium content of the fruit also showed a tendency to increase and then decrease, and both reached the optimal value at Ca3. The results show that Ca3 can be used as the optimal concentration to prevent and treat the black top disease of the fruit.

(1) at the beginning of the experiment, Calcium Spraying reduced the incidence rate of black top disease of jujube fruit. With the increase of calcium concentration, the incidence rate of black top disease gradually decreased. The activities of three antioxidant enzymes (SOD, POD, CAT) in jujube fruits increased gradually after Ca1, Ca2 and Ca3 treatment, and their activities were significantly higher than those of CK treatment. The content of vitamin C and calcium in jujube fruit increased first and then decreased, and reached the optimal value at CA3. The results showed that CA3 could be used as the optimal concentration for controlling black top disease of jujube fruit.<br>