Modeling the development rate of wheat cultivars

Mathematical plant development models based on meteorological or climatic factors,allows to estimate or predicate the crop maturity or others phenological developmentfor planting date decision. Data from wheat breeding trials, conducted over thecountry during 1982-1994 growing seasons, were used to developing models forestimating developmental stages (DS) of two wheat cultivars, namely: Omid andBezostaya. Developmental rate (DR) for emergence, stem elongation, heading andmaturity stages was determined by using the inverse of developmental duration as thedependent variable and various temperature variables and factorial combinations ofthese variables as the independent variables in a stepwise regression model. A step ofthe regression was considered appropriate, when the highest R2 was accompanied bythe significant (P<0.1) regression coefficient and partial coefficient of determination.Evaluation of model accuracy and sensitivity was performed using the data of Isfahanand Oromieh. Based on the ratio of absolute value of maximum deviation from theregression, to actual period of developmental stages, (expressed as the percentages)length of developmental stages were estimated well, that indicate efficiency ofcalculated models, especially for Omid cultivar. The results of this study indicate thatthe contribution of temperature and day length to various stages of development is notthe same. Thus, a separate model may be needed for each cultivar and each DR.Dividing the country to homogenous groups, with respect to temperature and daylength, may increase the accuracy of estimating models. This requires availability ofsufficient phenological information from various climatic zones.

کلیدواژه ها:

climate ، day length ، development rate ، modeling ، temperature ، wheat