（3）总体来看，钙溶液的施加能够提高枣果抗氧化酶（SOD、POD、CA

(3) Generally speaking, the application of calcium solution can increase the activity of antioxidant enzymes (SOD, POD, CAT), vitamin C content and calcium content of jujube fruit, thereby improving the ability of jujube fruit to resist adversity. However, excessively high concentrations of calcium will have an inhibitory effect, making the jujube fruit less resistant to stress and prone to jujube black top disease. From the results, the physiological indicators reached the optimal value under the Ca3 concentration, while Ca4 showed a certain degree of inhibition. Therefore, choosing an appropriate calcium solution concentration can not only promote the increase of the calcium content of the jujube fruit, but also improve its ability to resist adversity, thereby reducing the incidence. Avoid the application of high-concentration calcium solutions, which may cause excessive accumulation of calcium ions in plant cells, which may affect the absorption of other nutrients by jujube fruits. Spraying Ca3 is the best concentration to reduce the incidence of black top disease. In terms of production, it can be considered to regulate the growth and development of the jujube fruit by adjusting the concentration of calcium and the processing time to improve the nutritional and economic value of the jujube fruit. Since different varieties of jujube have different resistance to black top disease, the appropriate calcium concentration for preventing and controlling jujube black top disease cannot be generalized. The specific calcium solution concentration applied needs further study.

(3) Overall, the application of calcium solution can improve the activity of the antioxidant enzyme (SOD, POD, CAT), vitamin C content and calcium content, thereby improving the ability of the fruit to resist adversity. However, the excessive concentration of calcium agent will play a inhibitory role, so that the fruit resistance change is prone to the occurrence of black top disease. From the results, the physiological indicators at Ca3 concentration reached the optimal value, ca4 showed a certain degree of inhibition. Therefore, the selection of suitable calcium solution concentration can not only promote the increase of calcium content of the fruit, but also improve its ability to resist adversity, thereby reducing the incidence. Avoid the application of high concentrations of calcium solution, resulting in excessive accumulation of calcium ions in plant cells, which may affect the absorption of other nutrients by fruit. Spraying Ca3 is the best concentration to reduce the incidence of black-top disease. In production, it may be considered to regulate the growth and development of the fruit by regulating the concentration of calcium and processing time to improve the nutritional and economic value of the fruit. Due to the different resistance of different varieties of fruit to black-top disease, the appropriate calcium concentration for the prevention and treatment of black-top disease can not be generally discussed, the specific calcium solution concentration applied by the specific need for further study.

(3) In general, the application of calcium solution can improve the activities of antioxidant enzymes (SOD, pod, cat), vitamin C content and calcium content of jujube fruit, so as to improve the ability of jujube fruit to resist adversity. However, too high concentration of calcium can inhibit the growth of jujube fruit, which makes the stress resistance of jujube fruit worse and causes black top disease of jujube fruit easily. The results showed that the physiological indexes reached the optimal value under the concentration of CA3, while CA4 showed a certain degree of inhibition. Therefore, choosing suitable calcium solution concentration can not only promote the calcium content of jujube fruit but also enhance its ability to resist adversity, thereby reducing the incidence rate. Avoid the application of high concentration of calcium solution, resulting in excessive accumulation of calcium ions in plant cells, which may affect the absorption of other nutrients by jujube fruit. Spraying Ca3 was the best concentration to reduce the incidence rate of black top disease. In production, the growth and development of jujube fruit can be controlled by adjusting the concentration of calcium and treatment time, so as to improve the nutritional and economic value of jujube fruit. Due to the different resistance of different varieties of jujube fruit to black top disease, the suitable calcium concentration for controlling black top disease of jujube fruit can not be generalized, and the specific calcium concentration needs to be further studied.