Main Stem Height and Phenotypic Uniformity in Cotton Line Tt-3 (Cultivar Sp-03): Implications for Selection

Data collected under field conditions for 80 samples of cotton line TT-3 (cultivar SP-03) were used to compare grouping based on mean main stem height and the coefficient of variation of this trait. Eight clusters were identified separately for each parameter using Ward's method. Mean sample height ranged from 85.0 to 112.0 cm, and the coefficient of variation ranged from 3.1 to 5.8%. Identical mean heights were associated with different levels of within-sample variability. The results illustrate the value of considering both the mean and variability in preliminary selection of samples with a target trait level and high phenotypic uniformity.