The effects of water stress treatments in scots pine (Pinus sylvestris L.) seedlings on planting of a semi-arid area (5 years results)

Scots pine (Pinus sylvestris) has a large natural distribution area throughout the world, including semi-arid areas in Turkey. Scots pine is being used for the afforestation of semi-arid regions in Turkey. Determining the drought resistance of Scots pine provenances will increase the success of afforestation efforts in semi-arid land areas. In the first stage of this study, water-stress treatments were applied to ten provenances of one year old Scots pine seedlings in their second vegetation period (between April and November) and their diameter and height were evaluated in the nursery in order to determine their seedling morphology. Drought stress treatments consisted of: irrigation once a week (IR1), irrigation twice a week (IR2-Control), irrigation biweekly (IR3) and open field (IR4). Later, the water-stressed seedlings were planted in a semi-arid region (Bayburt, Turkey) and their survival and growth performance were evaluated over a five-year period. The nursery study showed that drought stress, provenance and their interaction had a significant effect on the morphological characteristics of the seedlings. Under water-stress conditions, the best growth performance was found in Dokurcun, Degirmendere and Dirgine provenances. Water-stress and provenance factors and their interaction also affected the field performance of the seedlings. Degirmendere, Dirgine and Dokurcun provenances also had the best performance under the field conditions. These provenances can be suggested for the afforestation sites having conditions similar to those of the study site.