The relationship between growth-ring width and ray density and ray height in cell number in the earlywood of Pinus halepensis and Pinus pinea

Abstract

The relationship between growth-ring width and ray size and number was studied in five 24-year-old trees of Pinus halepensis Mill. and five 16-year-old trees of Pinus pinea L. All trees of both Pinus species showed a gradual tendency for an increase in ray height, from an average of less than 4 cells near the pith to 7 or 8 cells in the outer rings. Ray number decreased from more than 70 rays per mm2 near the pith to about 40 rays per mm2 in the outer rings. No significant correlation was found between growth-ring width and the number of rays per mm2 or height of rays for three out of five trees of P. halepensis or for any of the five P. pinea trees. I conclude that there is no general direct relationship between growth-ring width and ray number and size.