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

The plant's vital cycle begins with seed germination in the soil. The length and seed rate emergence depends on the temperature, moisture and oxygen of soil and the quality of the seedbed. In irrigation conditions, temperature is one of the most influential factors on the emergence stage. In order to determine the seed emergence rate of safflower and soybean cultivars, planting dates of these cultivars during different years in research fields of Isfahan province were used. To determine the emergence rate the length of emergence period inversed. Emergence rate considered as dependent variable and thermal factors were used as independent variables in the stepwise regression. With increasing temperature, the length of the emergence period decreased. The coefficients of determination for determining the rate of emergence stage for safflower cultivars namely Arak, Sofeh and Goldasht, were ۷۵.۹۹, ۶۹.۷۵ and ۷۶.۰۷ percent respectively, and for soybean cultivars namely Hack, Williams and Steel, were ۶۳, ۷۰.۴ and ۷۰.۲ percent respectively. Based on the results, the contribution of heat parameters to determining the seed emergence rate of different cultivars is not constant.The plant's vital cycle begins with seed germination in the soil. The length and seed rate emergence depends on the temperature, moisture and oxygen of soil and the quality of the seedbed. In irrigation conditions, temperature is one of the most influential factors on the emergence stage. In order to determine the seed emergence rate of safflower and soybean cultivars, planting dates of these cultivars during different years in research fields of Isfahan province were used. To determine the emergence rate the length of emergence period inversed. Emergence rate considered as dependent variable and thermal factors were used as independent variables in the stepwise regression. With increasing temperature, the length of the emergence period decreased. The coefficients of determination for determining the rate of emergence stage for safflower cultivars namely Arak, Sofeh and Goldasht, were ۷۵.۹۹, ۶۹.۷۵ and ۷۶.۰۷ percent respectively, and for soybean cultivars namely Hack, Williams and Steel, were ۶۳, ۷۰.۴ and ۷۰.۲ percent respectively. Based on the results, the contribution of heat parameters to determining the seed emergence rate of different cultivars is not constant.

Emergence, Modeling, Safflower, Soybean, Temperature