عنوان مقاله [English]
Identification of phenological stages is the first step to study the plant response to environmental changes, such as climate, temperature, precipitation, fertilization, irrigation and biological control. In order to identify the phenological stages, 100 seedlings were studied at 5-10 days intervals. Stem and leaf length growth were measured by ruler and caliper to draw growth rate curve. Results showed that annual, biennial and 3- years old and older up to productive age of Pinus sylvestris were classified into 10, 10, 9 and 8 groups, respectively. Time of phenological stages was slightly different between biennial and older seedlings. Sigmoidal growth curve of biennial seedlings revealed that the effect of middle part of last year stem on increased seedling height was more than upper part (apical meristem). Hence any parameter that increases middle part of annual seedling will consequently increase the length growth of biennial seedlings. Stem elongation was affected by phenological stage of lammas shoot at the late growth season. Appearance of leaf buds coincides maximum length growth of seedling stem and young trees.