Seasonal changes of non-structural carbohydrates and amylase in twigs of Quercus brantii var. persica (Jaub. & Spach) Zohary

Quercus brantii var. persica (oak manna tree) is a valuable tree species in forests of western Iran. This species has been adapted to rough conditions of its habitat such as extreme summer and winter, long drought period and high elevation. For determining physiological patterns and alteration related to the establishment of oak in this environment, the changes of total non- structural carbohydrates and amylase activity in oak trees were studied in a less manipulated habitat during an annual cycle. The amount of total non- structural carbohydrates and amylase activity were measured by enzymatic and electrophoresis (PAGE) methods. Results indicated that non- structural carbohydrates concentration (glucose, fructose and sucrose) in March (before bud burst) was more than January ones. After bud burst and leaf expansion, when photosynthetic activity was high and after the beginning of drought period the concentrations of glucose and fructose increased continuously to September. Contrariwise the amount of sucrose and starch decreased slowly during this period. After summer and with falling temperatures, the total non-structural carbohydrates increased in November. In January, the content of starch was very low but the level of soluble carbohydrates was high. Thus the energy supply for metabolic processes in trees is secured during cold and hard winter seasons. Total non-structural carbohydrates ranged from 18.5 to 37.25 mg gdm-1. Seasonal changes of α-amylases coincided considerably with changes of starch and glucose concentrations of oak manna trees during the investigation period.