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Studium fytoplazmy ESFY a jejich projevů u odrůd meruněk a broskvoní
Kopřivová, Vladimíra
The aim of this study was to obtain detailed knowledge of the symptomatic expression of various isolates European Stone Fruit Yellows phytoplasma (ESFY) on selected rootstocks, susceptibility testing of selected rootstocks to phytoplasma ESFY and exploration of the extent and impact of phytoplasma ESFY to the biological properties of pollen, seeds, some phenological and pomological characters of varieties of apricot fruit. After three years of observation of pomological characterictics of fruits from ESFY infected trees and comparing to pomological characteristics of fruits from healthy trees of 16 apricots varieties the most susceptible varieties to ESFY were infected trees Arzami Aromatnyj, Hatif Colomer, Veselka and Vestar. These varieties were significantly reduced overall size and weight of fruit due to present ESFY phytoplasma. During the research no shrunken or deformed fruits were found, fruits from infected trees were just rounder than fruit from healthy trees. Effect of ESFY phytoplasma on pollen germination, early flowering, ripening time, soluble dry matter of the fruit and seed viability was not so significant. Symptomatic manifestation of the annual shoots grown through the inocula, originating from nine selected infected trees of different varieties of apricots and one peach tree and symptomatic manifestation of plants from five different rootstocks, which were inoculated, was during the three years of observing very diverse. It was found, that it is dependent on botanical species, variety, rootstock, growing conditions and the interactions of the pathogen and the host. The most susceptible annual shoots to present ESFY phytoplasma were the grown from inocula sampled from infected tree variety Jantze peach and Murfatlar apricot. Chlorotic leafroll, yellows and growth depressions appeared most on annual shoots. The least susceptible response to ESFY phytoplasma was demonstrated on shoots grown through from inoculum originating from apricot tree variety Poyer. In this variety there were the most numerous shoots without symptoms compared with other varieties. In most varieties (Jantze, Saldcot, Poljus Južnyj a Hargrand_2) with a higher frequency of positive shoots the chlorotic leafroll was the most represent symptom, so it will be a typical symptom for ESFY pyhtoplasma. Symptomatic manifestation of rootstock plants in combination with inocula from ten selected varieties reached lower frequency of evaluated characteristics compared to annual shoots. Based on the resulting reaction of shoots grown through inocula of tested varieties and reaction of rootstock plants to presence of ESFY phytoplasma, the most susceptible rootstock was GF 305, susceptible rootstock was GF/8/1, less susceptible was M/LE/1 and the least susceptible rootstocks were Torinel and St.Julien 655/2. Sensitivity reaction of rootstocks file to present ESFY phytoplasma was observed for three years at fifteen selected rootstocks, whose plants were inoculated by two inocula from different varieties. Rootstocks plants without any symptoms had the highest frequency (84.37 %), and the most widespread symptom was the leaf yellows (average 10.5 %). Rootstocks were divided into four groups according to their susceptibility to ESFY phytoplasma. The most susceptible response was manifested on rootstocks GF 305 and GF 677, rootstocks MRS 2/5, VVA1, Strážovický myrobalán, Lesiberian, AP1 and GF 31 were susceptible, rootstocks M/LE/1 and Myrobalán 29C were less susceptible and the least susceptible rootstocks to ESFY phytoplasma were Torinel, St. Julien 655/2, GF/8/1 and MY/KL/A.
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