[Effect of time of the year and height of prunning on the flower production and the content of Essential oil in Rosa damascena]

This work was carried out in Dahr aljabal of Swaida Syria during 2010 -2011- 2012 on rosa damascena to investigate the effects of cultivation method, prunning height at different times of the year on the flower production and the content of essential oil in the flowers.Shrubs were brought from almarah (the village of damask roses) and cultivated in a site which rises 1835 meter above sea level in tow different cultivation method at spacing of (2x3) meter .Shrubs were prunned at three different times: November, January and March and at three different heights for each time(10,25,40)cm above soil level. Some Shrubs were left without prunning as a control treatment. The results of the experiment were collected where the analysis of variance showed the following: First: Prunning is very necessary to rosa damascena. When the shrubs were prunned after leaves falling at all studied times, flower production per shrub was increased and so was the content of essential oil in the flowers in comparison with non prunned Shrubs. However ,the late pruning after the shrubs 126 resume growth' flower production was reduced and so was the content of essential oil in the flowers.Secondly: The best time of prunning for rosa damascena in study site was January. At this time of the year for prunning, flower production was increassed and reached an average of (656.7) flowers per shrub, and the content of essential oil in the flowers reached an average of (0.029%), in comparison with shrubs were prunned at either October or March.Thirdly: Shrubs were prunned to (40cm) above soil level showed an increment of flower production which reached an average of (735.8) flowers per shrub and the content of essential oil in the flowers reached an average of (0.029%) in comparison with shrubs were prunned to 10cm and 25 cm above soil level.Fourthly: results showed a positive interaction between the time and the height of prunning.A maximum flower production was obtained when shrubs were prunned in January to (40cm) above soil level which reached an average of (1067.7) flowers per shrub and the content of essential oil in the flowers reached an average of (0.032%) in comparison with all other interaction treatments.Fifthly: shrubs were cultivated between young apple trees in a resent orchards showed an increment in the content of essential oil in the flowers . however, cultivation method had no effect on the flower production, fresh flower weight and the number of the new offsets.