Assessing the relationship between leaf area and some vegetative characteristics in safflower

To find a quick and reliable method to estimate leaf area in safflower cv 'Local Esfahan', a factorial experiment based on completely randomized block design was conducted with four replicates and two factors included sowing date (5 and 25 April and 18 May) and plant density (15, 40, 65 and 90 pl/m-2). In the present study, leaf area was estimated through leaf number on main stem, node number on main stem, leaf dry weight and stem dry weight by the different regression models. Based on RMSE (root mean squares of error) and R2 (determinant coefficient) estimated for studied models, leaf dry weight was the best independent variable to estimate the leaf area. The relationship between leaf area and leaf dry weight described by a linear model. The values of RMSE varied between 24.39 and 61.35 for different densities and the values of R2 was higher than 0.96. This indicates that model could predict leaf area by leaf dry weight. It was found no significant difference between the slopes of linear model fitted on leaf area data against leaf dry weight. Therefore, a general model was fitted on these data using all densities and the values of the a and b coefficients were estimated as 9.7 and 108.7, respectively.