عنوان مقاله [English]
This experiment was conducted in Rikhalan Experimental Station in Marivan city of Kurdistanprovince of Iran in 1999 and ended in 2006. In first phase, (nursery selection) 29 genotypes of walnut (Juglans regia L.) were studied, under Randomized Complete Blocks Design (RCBD) with four replications in three years. The measured tree characteristics were: height, collar diameter and survival. Based on the results of first phase, for the second phase, five genotypes of walnut (J–2, J–10, J–17, J–18 and J–19) were selected and planted under Split Plots Design with three replications during seven years (1998–2006). The main plots were: Control and soil surface with mulch cover and the secondary plots contained five walnut genotypes. Results showed that there were only significant differences between the main treatments in respect to the growth characteristics (p < 0.01). Survival, crown diameter, height and collar diameter of the walnuts at plots applied with plant material mulch (oak chipped branches) were significantly greater (96.7 %, 72.6 cm, 135.9 cm and 37.4 mm, respectively) than the walnuts at control plots (77.9 %, 50.1 cm, 95.6 and 28.4 mm, respectively).