Resistance of New Semi-Dwarfing Pear Rootstocks to Fire Blight In Vitro and Greenhouse Conditions

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Abstract

Fire blight is an important disease of pome fruits including pears, and cultivation of resistance cultivars and rootstocks are one of the most effective methods for disease control. In this study, resistance of OHF87 and Pyrodwarf semi-dwarfing pear rootstocks were compared with two control cultivars, Dar Gazi (resistant) and Bartlett (susceptible)
in greenhouse and in vitro conditions. Following propagation of pear rootstocks, they
were inoculated with a mixture of Ea273, K1 and Z2 strains of the pathogen
(Erwinia amylovora) and progress of the disease were evaluated during 6 and 14 days after inoculation in vitro and greenhouse conditions, respectively. Greenhouse evaluation results demonstrated most resistance level at Dar Gazi cultivar, followed by OHF87 and Pyrodwarf rootstocks and Bartlett. In vitro evaluation results also confirmed the greenhouse ranking of tested pears. Indices of varietal susceptibility and necrosis progress rate were used in greenhouse evaluations, while in vitro conditions necrosis progress rate was the solitary effective index for disease evaluation. Finally, in a complementary in vitro test, evaluation of new pear rootstocks with the same control cultivars showed a classification of resistance, from OHF69 > OHF87 > Dar Gazi > OHF333 > Pyrodwarf > Barttlet > OHF40 > Fox11. Based on the results, three OHF69, OHF87 and OHF333 demonstrated high levels of disease resistance, while for propagation and extension of OHF40 roots tocl, more investigation should be carried out.

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Seed and Plant Journal
Volume 30, Issue 2
September 2014
Pages 227-242

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