Published in Scientific Papers. Series A. Agronomy, Vol. LXIV, Issue 1
Written by Steliana CLAPCO
Broomrape (Orobanche cumana Wallr.) is a non-photosynthetic, obligatory, root parasitic plant, that specifically infects sunflower crop, causing significant yield losses. The parasite is widely spread in the majority of sunflower growing countries from Europe, Middle East and Asia. In the last years broomrape rapidly evolves, developing more aggressive races, which spread to new areas. In order to understand dynamics of pathogen populations and their adaptation to environment the knowledge related the virulence and aggressiveness of plant pathogens are required. Contrary to virulence which reveal the qualitative component of pathogenicity that is expressed vertically, aggressiveness refers to the quantitative variation of pathogenicity on susceptible hosts, without any restriction related to specificity. Present study was focused on the evaluation of aggressiveness of different broomrape populations belonging to different countries, such as Republic of Moldova, Bulgaria, Serbia, Romania, Ukraine, Spain, Turkey and China. Experience was carried out in green house using different sunflower genotypes (without qualitative resistance or genes or caring some or genes). The numbers of aerial and underground broomrape shoots, as well as of tubercles were counted and the frequency, intensity and degree of attack were calculated. The significant differences between broomrape populations for all analysed parameters were found. Thus, the most aggressive populations were those belonging to Soroca, Republic of Moldova and Ismail, Ukraine, followed by some populations from Turkey and Romania.
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