كليدواژه :
گردوي پاكوتاه , مديريت باغ گردو , breeding , Dwarf walnut , Tree size , Walnut orchard management , ارتفاع نهال , بهنژادي
چكيده لاتين :
Accoring to the frequent observation of precocious and dwarf walnut genotypes in Iran nurseries, this study was conducted to collect and evaluate these valuable genotypes during 2000-2005, in northwest of Iran. Several seedlings were inspected and 125 phenotypes showing one or more dwarfing characteristics had been selected for further investigations on the stability of characters. The selected seedlings were randomly planted in a separate field plot spacing 4 x 4 m. After five years of planting, different characteristics of genotypes including tree size, shoots length, crotch angle, number of nodes, internode length, leaf area and number of fruits were recorded. There were significant positive correlations between size of the tree and other traits except crotch angle and fruiting, which showed a significant negative correlation (-0.39 and -0.42, respectively) with the tree size, These dwarf trees had shorter internodes, less nodes as well as wide crotch angles and good fruiting ability. Cluster analysis of genotypes revealed three clusters of genotypes, each of them had a significantly distinctive characteristic. In the main cluster, mean of tree size, number of nodes and length of nodes were 46.12, 7.70 and 1.05, respectively. The similar results were achieved by factor analysis using two principal components (pel and pc 2). The structure of phenotypic diversity of clusters and the centralization of most of the genotypes in the main cluster to some extent indicated the genetic stability of evaluated genotypes. Morever, the possible genetic mechanisms and the role of natural and artificial selections as well as the importance of these dwarf and semi-dwarf genotypes for developing new horizons in walnut orchard management has been discussed.
