Effects of induced drought and tilting on biomass allocation, wood properties, compression wood formation and chemical composition of young Pinus radiata genotypes (clones)

Abstract

Abstract Eight genotypes (clones) of Pinus radiata were subjected to drought and stem inclination to assess genotype response to common stressors. While drought stress reduced diameter growth, height growth and total biomass accumulation, root to shoot (R/S) ratios were unaffected. Drought-stressed plants had significantly lower average acoustic velocity, but longitudinal shrinkage (LS) and density were not different from those of the control plants. Radial diameter growth and R/S ratios were unaffected by tilting. Inclined stems had significantly lower acoustic velocity, and significantly higher LS and density than control stems. Acoustic velocity had a strong negative correlation with LS (r2=0.79). Compression wood (CW) content was much higher in tilted plants, compared to control and drought treatment plants. The CW of tilted trees had different chemistry than that of the CW of drought and control plants. Genotypes differed significantly in the amount of CW formed as a response to tilting, demonstrating that the formation and extent of CW is genetically influenced. Mechanical perturbation in conjunction with acoustic methods for assessing stiffness would be a useful approach for early-age selection of genotypes less prone to form CW.