Relationship of seasonal changes in carbohydrates and cold hardiness in buds of two rose hip genotypes

Two rose hip types thorny '25-mrk-14' (Rosa canina L.) and thornless '25-mrk-15' (Rosa dumalis Bechst.) selected from previous studies were used in this investigation. Samples of one year old twigs were collected and exposed to the artificial freezing test at -30degreesC for 0, 8, 16 and 24 hours from November through March. Throughout the experiments, several biochemical analyses on the buds of the rose hip genotypes, including total sugar, reducing sugar, sucrose and starch were performed monthly. Results indicated that there was a significant difference between the species of rose hips for resistance to cold, according to hours of treatment and month of samples taken. The '25-mrk-15' was less resistant than the '25-mrk14' in terms of cold hardiness. Freezing tolerance in both rose hip genotypes is higher in January and February than November and December. The sugar ingredients of rose hip types increased from November to February, but decreased in March.