An Investigation of Cold Tolerance on Chemical Properties (Proline, Protein, and Sugar) of the Flower Buds in Four Commercial Cultivars of Damghan Local Pistachio

Temperature reduction in early spring, especially corporate with buds swelling, sometimes causes severe damages. Most of the fruit trees in tropical and semi-tropical regions, especially in more critical conditions, moderate, at early spring are subjected to the frostbite and winter cold injuries. This study aimed to evaluate the amount of proline, total protein, and soluble sugars during the phonological period of buds under the late spring cold. So the research as factorial in completely randomized design with two factors, first factor was sampling time (1-mid- February 2- swelling of inflorescence buds 3-flowering 4-fruit set) and the second factor was four local pistachio cultivars of Damghan city (Shahpasand, Khanjari, Abasali, and Akbari cultivar) was established in three replications in the Damghan’s regions. The results indicated that the highest amount of proline under cold stress in flowering stage was reported in Khanjari cultivar and the lowest amount in Shahpasand and Akbari cultivar. Also the result indicated that the highest amount of protein in flowering was observed in Khanjari cultivar and lowest amount in Akbari and Shahpasand varieties. Due to temperature reduction the total amount of proteins during the dormancy and swelling were decreased but during the flowering and fruit setting the total amount of protein was increased. During the winter, sugars were accumulated but their level decreased in early spring.