Evaluation of Early Rooting Traits of Eastern Cottonwood That Are Important For Selection Tests

Vegetative propagation of superior genotypes via stem cuttings depends on their development of strong vigorous root system. Fourteen characters of cutting rooting were examined in multiannual tests with 12 genotypes of eastern cottonwood (Populus deltoides BARTR. EX MARSH) in course of evaluation of their utilization in selection tests. Variability and relationship among examined characters, and cutting survival rate were analyzed according to contribution of expected variances to the total variance and results of principal component analysis, stepwise regression analysis and path analysis. Along with total number and length of first-order roots, the characters that are regularly used in the assessment of rooting potential, our results signify dynamic shoot growth and uniform arrangement of roots on cutting at the beginning of growing period. The best results were obtained for shoot height at the second half of May. A rapid and non-destructive way of shoot characters’ measurement allows testing of larger material and prevents losses in propagation material of interesting genotypes. Alone or together with total root number and length these alternative characters could be used for the improvement of selection tests and procedures for cultivar technology design.