تعيين درجه حرارت تجمعي در مراحل فنولوژي سه رقم خيار (Cucumis sativus L.)

Determination sum of temperature in phenology stages of three cultivars of cucumber (Cucumis sativus L.)

Growth prediction was investigated based on environment temperature in Gorgan University of Agricultural Sciences and Natural Resources. This study conducted to determining thermal time (GDD) in different phonological stages of three cucumber cultivars (Green Gold, Dharwad and Super Dominus). Results showed that Super Dominus and Green Gold cultivars germinated after received 93.25 and 117.62 degree day were the earliest and latest respectively. Amount of temperature required for beginning of flowering was 321.75 GDD which was more than for its first side branches formation (289.75 GDD) in Dharwad. In aspect of harvesting time Super Dominus after 44 days with accumulation of 453 degree days was earliest variety and latest variety was green gold that its harvesting time occurred with accumulation of 626.75 GDD. The days which needed for realization of different phenological stages, as a function of temperature, can be calculated with following equation, t=S.(T-Tmin)"1 Where T is mean temperature in °C; Tmin is the minimum theoretical temperature for germination or growth in °C; S is sum of temperature in °C during time which special phenomena occurred and t is the time in days. This is very applicable tool for predicting the time of planting, cultivation, harvest and stage of flowering, stem formation, fruit set during growth and development of plants for fertilizer management, irrigation and act by farmers or researchers.