Primary Growth Effect of Salix viminalis L. CV. Inger and Tordis in Controlled Conditions by Exploring Optimum Cutting Lengths and Rhizogenesis Treatments

Abstract

The major disadvantage of setting up a willow coppice is the low survival rate, which reduces economic efficiency and crop sustainability. The aim of this research was to test, under controlled conditions, the impact of water, gibberellic acid A3 (0.05%), and humic acid (0.2%) on the growth and development of two willow clones. Under humic acid treatment, 20 cm cuttings of the Tordis clone developed up to 15 roots, and 25 cm cuttings developed more than 23. In comparison, water stimulated more than 15 roots for both 20 and 25 cm cuttings. Gibberellins acted as an inhibitor, especially on the roots, and the cuttings dried out from the top to the middle, with weak development of shoots and callus formation. For both clones, the highest number of active buds was observed on 20 and 25 cm cuttings grown in water, with more than four for Inger and more than seven for Tordis. Root development of the Inger clone had a maximum of eight for 25 cm cuttings grown in water; it was three times lower in the same variant of Tordis and two times lower for the Tordis clone with humic acid treatment. In general, Inger cuttings of 15 and 25 cm highlighted a delayed root formation when humic acids and gibberellins were applied. In controlled condition experiments, the Tordis clone was more suitable owing to its higher development and increased growth stability.