Clone differences among young Salix humboldtiana Willd. from Patagonia

Abstract

Key message: When growing under similar conditions, Salix humboldtiana plants exhibit intra- and inter-clone variations in growth and branching traits, despite sharing an acrotonic branching pattern. Abstract: Willows represent some of the most extended tree crop species worldwide. Understanding their global architecture could help improving the forestry based on these species and thus the associated economic activities. Our goal was to compare growth and branching traits among clones of Salix humboldtiana, the only willow native to South America. We registered the length, diameter, number of branches, branching range and the number of growth units of the vertical shoot formed by plants derived from nine clones of three Patagonian provenances of S. humboldtiana. Budbreak patterns at each node of that shoot were also analyzed. Length and number of branches were the most variable among clones, while diameter and branching range were the least variable shoot traits. The clones with the highest proportion of unbranched individuals tended to have the lowest proportion of shoots with two growth units. The probability of budbreak decreased as the distance between a bud and the shoot apex increased (acrotonic branching pattern). Our study shows that the length and the number of branches of the main axis growth unit would be key traits for clone selection, as they seem to have a high degree of endogenous determination. These traits are important aspects of the whole plant’s architecture that can be used for designing, for example, agroforestry systems when it comes to clone or even species combination.