Determination of Growth Degree Days (GDD) for different phonological stages of Kair (Capparis decidua (Forssk.) Edgew) in Iran

In order to survey some phenological phenomena of Kair with climate and physiography properties, this study was carried out in the south-east of Iran from 2008 to 2011. In the first step, distribution of species was recognized in Hormozgan and Balochestan provinces and then 13 habitats were chosen. These habitats were visited in 2-3 week intervals annually. Three trees were marked in each site and were monitored during four seasons and its phenological stages (time of bud break, flowering, fruiting, ripening, fruit, and leaf shedding) and other characteristics were recorded. Climatic data were gathered and phenological stages were analyzed. The results of phenological and meteorological data indicated that the growth patterns of Capparis decidua may alter with fluctuations of drought, annual temperature and precipitation. The phonological stages are repeated two or three times every year. Kair phonological stages are long, Flowering starts during March and continues up to October. It flowers in three seasons: March–April (spring), June-July (summer) and September-October (Autumn). Flowers become fruits within 70 to 90 days and simultaneously, both flower and fruit appear on new shoots. In the northern and western habitats, phonological stages are limited and only occur once or twice a year. But in all conditions, amount of growth degree days (GDD) required for ripening seed is the same and equal to 931ْ ^C.