Comparison of basic density and longitudinal shrinkage in tension wood and opposite wood in young stems of Poplar (P. euramericana cv “ Ghoy ”) when subjected to a gravitational stimulus

In a green house, under controlled conditions, young shoots, taken from poplar cuttings (P. euramericana cv “ Ghoy ”), were artificially inclined in order to quantify the modifications of physical properties induced by a gravitational stimulus. At the end of the growing season, basic density and longitudinal shrinkage were measured on very small samples taken from pure tension wood tissue observed on the upper face of the inclined axis and compared with opposite wood tissue, free of gelatinous fibers, developed on the opposite lower face. In a second step, shoots bend at two different lean intensities were analyzed.
On young poplar wood, gravitational stimulus was found to have a significant effect on physical properties. Relations between basic density and longitudinal shrinkage are different depending on the types of wood considered. Shrinkage appears more sensitive to lean intensity in the range considered here