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 causessevere damages. most of the fruit trees in tropical and semi-tropical regions, especially in more criticalconditions, moderate, at early spring are subjected to the frostbite and winter cold injuries. this study aimed toevaluate the amount of proline, total protein, and soluble sugars during the phonological period of buds under thelate spring cold. so the research as factorial in completely randomized design with two factors, first factor wassampling time (1-mid- february 2- swelling of inflorescence buds 3-flowering 4-fruit set) and the second factorwas four local pistachio cultivars of damghan city (shahpasand, khanjari, abasali, and akbari cultivar) wasestablished in three replications in the damghan’s regions. the results indicated that the highest amount ofproline under cold stress in flowering stage was reported in khanjari cultivar and the lowest amount inshahpasand and akbari cultivar. also the result indicated that the highest amount of protein in flowering wasobserved in khanjari cultivar and lowest amount in akbari and shahpasand varieties. due to temperaturereduction the total amount of proteins during the dormancy and swelling were decreased but during theflowering and fruit setting the total amount of protein was increased. during the winter, sugars wereaccumulated but their level decreased in early spring.