Impact of Climatic Factors on Radial Growth in Walnut (Juglans regia L.)

Walnut is a species of high vigour, with relatively slow growth, and the size of trees grows with each year of growth. Accumulation of wood biomass, and respectively, productivity, is a resultant synthesis of physiological processes and interaction of trees with environmental factors. The authors have assessed growth characteristics of genotypes standing on their own roots in the sands area of Oltenia (Romania). In terms of tree height, it ranged from 8.53 m to 18.00 m, while trunk circumference varied between 40 cm and 229 cm, in genotypes with ages between the 16 and 44 years. Environmental factors, by influencing cambium tissue activity, cell differentiation processes, cell walls growth processes, are inducing particular characteristics of annual rings, in terms of size. The average value of growth ring was 7.09 mm, with a minimum of 3.53 mm, a maximum of 13.94 mm and variation coefficient of 40.20%. The obtained results show that climatic and edaphic factors of the culture area are influencing the trees growth and development and indicate a good adaptability of genotypes to these conditions.