Articles
CORRELATION OF VEGETATIVE TRAITS WITH FIRE BLIGHT RESISTANCE IN IRANIAN AND IMPORTED APPLE CULTIVARS
Article number
896_47
Pages
347 – 352
Language
English
Abstract
In order to establish the level of genetic susceptibility of the existing native and imported apple (<i<Malus domestica Borkh.) cultivars to fire blight in the national apple collection, 108 cultivars were evaluated in Kamal Abad Research Station (Karaj-Iran). Genetic resistance of cultivars was assessed by using the following parameters: age of infected shoots, shoot position on the tree and progression of disease symptoms on tree crown under natural field infection conditions.
Infection intensity was calculated on 3 mature plants grown at similar orchard management for each cultivar.
Annual visual recordings were made at the end of July, in a triennial, 2005-2007, investigation period (Hajnajari, 2008). Specifically, we tried to study the probable correlations between 16 vegetative traits, as described in the National Guideline for the conduct of tests for distinctness, uniformity and stability in apple (Hajnajari et al., 2008), and genetic resistance to fire blight in 30 apple cultivars.
The first phase of triennial investigations showed that only the local cultivar Ardebil2 was put in the semi-susceptible class, while Golden Smoothee, Jonathan, Yellow spur, Stayman, Red Rome Beauty, Red Astrakhan, Yellow Transparent and Granny Smith fell in the intermediate class, but the new releasing early EUPRT with upright growth habit and 2 other early native cultivars under registration procedure called Sheikh Ahmad and Mashahd-e Nouri, together with Northern Spy and Red Spur were classified in the very resistant class while the rest of the cultivars were grouped as semi-resistant.
Correlation investigations between morphological traits and resistance to fire blight demonstrated that leaf width, marginal leaf dentations, leaf pubescence of lower laminar page and bearing habit were positively correlated to disease susceptibility.
In contrast, vegetative traits such as cortex color of annual shoots and leaf length to width ratio were negatively correlated to disease resistance.
Infection intensity was calculated on 3 mature plants grown at similar orchard management for each cultivar.
Annual visual recordings were made at the end of July, in a triennial, 2005-2007, investigation period (Hajnajari, 2008). Specifically, we tried to study the probable correlations between 16 vegetative traits, as described in the National Guideline for the conduct of tests for distinctness, uniformity and stability in apple (Hajnajari et al., 2008), and genetic resistance to fire blight in 30 apple cultivars.
The first phase of triennial investigations showed that only the local cultivar Ardebil2 was put in the semi-susceptible class, while Golden Smoothee, Jonathan, Yellow spur, Stayman, Red Rome Beauty, Red Astrakhan, Yellow Transparent and Granny Smith fell in the intermediate class, but the new releasing early EUPRT with upright growth habit and 2 other early native cultivars under registration procedure called Sheikh Ahmad and Mashahd-e Nouri, together with Northern Spy and Red Spur were classified in the very resistant class while the rest of the cultivars were grouped as semi-resistant.
Correlation investigations between morphological traits and resistance to fire blight demonstrated that leaf width, marginal leaf dentations, leaf pubescence of lower laminar page and bearing habit were positively correlated to disease susceptibility.
In contrast, vegetative traits such as cortex color of annual shoots and leaf length to width ratio were negatively correlated to disease resistance.
Publication
Authors
H. Hajnajari, S. Tarrahi, Z. Ghahremani
Keywords
apple, fire blight, genetic tolerance, vegetative traits
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