Talat Yasari - Department of Science, Zabol University, Zabol, Iran
Mohammad Reza Shahsavari - Horticulture Crops Research Department, Isfahan Agricultural and Natural Resources Research and Education Center, AREEO, Isfahan, Iran

Awareness of the role of temperature and day length on plant growth and development can be used in agronomic management and plant breeding, and provide basic and essential information for prediction of development stages. To estimate the length of development stages of a soybean variety namely Wood Worth using the temperature, day length and planting dates of this variety in different regions of Isfahan during ۱۹۹۶-۱۹۹۹. To determine the model of each stage, the length of each stage as a dependent variable and thermal variables, day length, and the product of multiplication of thermal variables with day length variables were used as an independent variable in step wise regression. For all stages by delaying in planting, the length of the stage decreased. The coefficients of determination for planting to emergence, emergence to flowering, emergence to poding and emergence to maturity were ۷۶.۴%, ۸۵.۶%, ۸۶.۹% and ۹۲.۲%, respectively. The results of this study show that the contributions of thermal parameters play a major role in determining the estimation models of development stages of Wood Worth variety.Awareness of the role of temperature and day length on plant growth and development can be used in agronomic management and plant breeding, and provide basic and essential information for prediction of development stages. To estimate the length of development stages of a soybean variety namely Wood Worth using the temperature, day length and planting dates of this variety in different regions of Isfahan during ۱۹۹۶-۱۹۹۹. To determine the model of each stage, the length of each stage as a dependent variable and thermal variables, day length, and the product of multiplication of thermal variables with day length variables were used as an independent variable in step wise regression. For all stages by delaying in planting, the length of the stage decreased. The coefficients of determination for planting to emergence, emergence to flowering, emergence to poding and emergence to maturity were ۷۶.۴%, ۸۵.۶%, ۸۶.۹% and ۹۲.۲%, respectively. The results of this study show that the contributions of thermal parameters play a major role in determining the estimation models of development stages of Wood Worth variety.

Development stages, Flowering, Metrological elements, Modeling, Soybean