Relation between moisture content and early growth in stem cuttings of selected fast-growing willow clones

Abstract

Short rotation biomass plantations with Salix spp. are established with stem cuttings prepared from one- to two-year-old dormant coppice shoots. The quality and physiological condition of cuttings are critical for survival and establishment of plantations. Provided that the stems used for cuttings are healthy and dormant at the time of harvesting, the main risk of deterioration is from the storage conditions. Moisture loss during storage is regarded as the most critical factor to rooting and survival of woody cuttings. Cuttings of nine selected clones of Salix viminalis, S. dasyclados and S. daphnoides were left to dry for different time intervals in controlled conditions and the survival rate and early growth response at different moisture levels were recorded. The ability to withstand lower moisture content varied significantly between species and clones. Two different types of response were demonstrated among the willows. S. dasyclados and S. daphnoides clones tended to resist drying better, while S. viminalis clones showed variation and generally tolerated moisture loss better than clones of other species tested. Sprouting was more affected by low moisture content than rooting in all clones. The sensitivity in some of the clones to even moderate moisture loss suggests that recommendations to water soak Salix cuttings before planting should be a standard procedure in the establishment of biomass plantations with willows.