Document Type : Research Article
Authors
Temperate Fruits Research Center, Horticultural Sciences Research Institute, Agricultural Research Education and Extension Organization, Karaj, Iran
Abstract
Ten apple promising rootstocks (Azop(385), AZ × M9(285), AZ × M27(85), Azop(285), AZ × M9(185), Azop(286), Azop(386), M9op(387), B9op(87), Azop(486)) were evaluated for resistance to crown and root rot caused by Phytophthora cactorum based on a completely randomized design with six replicates. Fungal inoculum was applied around the crown of each rootstock. Three to seven months after inoculation, the response of hybrids to the fungus was assessed based on root rot (%), crown length rotted, and crown girdling. The highest percentage of root rot belonged to MM106 and B9op(87), and AZop(486) (with 41.3 and 32.7%, respectively). Maximum crown rot was measured on MM106 (83.9%), B9op(87) and M9op(387), respectively. The greatest crown circumference girdled incidence was on MM106 followed by M9op(387), B9op(87). Adjusted Selection Index of Ideal Genotype (ASIIG) was calculated based on ideal and non-ideal distance. The rootstocks of AZop(385), Azop(285), and Az × M27(85) with the index value of 0.948, 0.937 and 0.8884, respectively, had the highest desirability among all rootstocks. These genotypes received a better place compared to M9. The least desirability belonged to MM106, M9op(387) and B9op(87) with the index value of 0.395, 0.375 and 0.343, respectively. The dendrogram generated from ASIIG, classified Azop(285), Azop(385), Az × M27(85) and M9 (as standard resistant rootstock) with the minimum distance to the hypothetical ideal genotype in the same group. Furthermore, Azop(386), M9op(387), B9op(87) with MM106 (as standard susceptible rootstock) were grouped at non-ideal quarter. A larger distance was found between other hybrids and the hypothetical ideal genotype.
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