A Growth Curve Application to Compare Plant Heights and Dry Weights of Some Wheat Varieties

In this study, plant height and plant dry weight of five wheat varieties (namely Da da 94, K nac 97, Konya 2002, Karahan 99 and Ahmeta a), collected for 20 weeks, were modeled via fitting generalized logistic (GLC), logistic (LC) and Gompertz (GC) growth curves. Growth curve selection was based on residual sum of square (RSS) and mean square error (MSE). Following growth curve selection, growth curves of wheat varieties and their parameter estimates were compared via a sum of square reduction test. Results from growth curve fitting show that GLC and LC produced similar RSS and MSE values while GC resulted in higher RSS and MSE values both for plant height and dry weight. Since parameters of LC have meaningful biological interpretation, it was chosen for plant height and dry weight modeling. Results from the sum of square reduction test show that Ahmeta a has the highest plant height potential (124.3 cm) while the varieties Konya 2002 and Karahan 99 have the smallest (102.6 cm). Konya 2002 is the variety that reaches maximum absolute growth rate earliest (9.29 weeks) while Karahan 99 reaches it latest (10.37 weeks). Asymptotic dry weight of all wheat varieties was found to be 43.27 g. Results also show that all varieties reaches to maximum growth rate at 14.89 weeks, except the variety Konya 2002 that reaches the same stage at 14.03 weeks.