Evaluation of irrigation interval on yield and its component for three cutivars of rapeseed and determination of optimum based on fuzzy decision making teory

In order to study the effect of irrigation interval on yield and yield components on three spring type variety of rapeseed) (Brassica napus L.) (a field experiment was conducted in 2005 at darab collage of agriculture، located in darab region (Bakhtajered Station). the experimental design was randomized complete block in split plot arrangement with three replication. main plots were four irrigation levels) 30، 60، 90 and 120milimeteres evaporation from A class pan)، and three type rapeseed are allocated as sub plot. The results indicated that increasing irrigation interval significantly decrease seed yield and 1000 seed weight. Highest and lowest yield respectively is related to irrigation interval 30 and 120 milimeteres evaporation based on A class pan. Decreasing of irrigation interval is caused increasing 1000 seed weight، although there are no difference between 30، 60 and 90 irrigation interval based on evaporate of A class pan. Highest and lowest 1000 seed weight respectively obtained of Hayola401 and RGS003. Irrigation interval didn’t significantly affect on seed oil percent and harvest index although with increasing irrigation interval seed oil percent decreased and HI increased. Finally by fuzzy decision making، calculated benefit of each choise (Irrigation interval – Variety). Irrigation interval 120 for Hyola 401 cultivar with 188. 8 degree benefit elected as best choice in Darab region. This choise، also has the best position on based of analysis of variance by MSTATC.