The present study was carried out to investigate the effect of fertilization levels, years of adding fertilizers, and age of growth rings on some anatomical properties of young Pinus brutia Ten. Trees grown in Nineveh forest.. The results show that the studied factors had a significant effect on most properties. Generally, the fertilizing treatments have led to a decrease in length and cell wall thickness of tracheids and also in rankel ratio, but to an increase in the averages of tracheid diameter compared to those samples taken from untreated trees. The effect of fertilization increases with the increase in ratios constituting it, the fertilizing treatment (70 gm compound fertilizer, 750 ppm. Iron and 30 or 45 ppm. Zinc) scored the highest ratios of a decrease in tracheid length (27.54 %), tracheid wall thickness (33.75 %), and rankel ratio (77.60 %). The same treatment has led to obtain the highest ratios of increase in tracheid diameter (54.84 %) compared to the untreated samples.
Concerning the effect of growth ring, it is evident that the highest ratios of the decrease have noticed in the tracheid length and tracheid wall thickness, while the highest ratios of increase appeared in tracheid diameter in the fifth ring compared with control. Addition of fertilizer in the fourth year of age has led to a highest decrease in the length of tracheid, wall thickness, and rankel's ratio compared to the addition for two successive years of age, while no clear effect has been noticed for the years of adding the fertilizer on tracheid diameter. |