The present investigation was carried out during two successive seasons 2018 and 2019 on Red globe grape Cv.to study the effect of chitosan at 0.5% or 0.75% and calcium chloride at 2% and their combinations  on the yield per vine and it's quality. Spraying was achieved either at pea stage (mid of April-first date of spraying) or at veraison stage (mid of June-second date of spraying). Besides ,calcium chloride at 2% was sprayed at veraison stage at mid of June.
Results showed that date of spraying chitosan at 0.5%  had no significant effect on the studied parameters (weight of cluster and yield per vine). In the same time, number of sprays (once or twice) had significant effect in the two used concentrations except the highest concentration of chitosan since no static difference had been noticed between spraying it at mid of June and the two sprays (mid-April+ mid-June). It's deserve to mention that the less cluster weight and yield per vine was of that of the control. In other words all treatments were superior than the control in this respect. The differences between them were proved statistically. Spraying vines with chitosan at 0.75% combined with calcium chloride at 2% at mid of June presented the heaviest cluster weight and yield per vine either compared with the control or any other treatment. The differences between them were statistically significant in the two experimental seasons. Finally, all treatments had  increased the yield per vine and improved it' s quality.