Dynamics of change in broomrape populations (Orobanche cumana Wallr.) in Romania and Russia (Black Sea area)

Abstract The emergence of new broomrape populations (races) has been observed in the past 20 years in several countries (Romania, Moldova, Ukraine, Russia, Turkey, Bulgaria, Spain, Serbia, and China) where sunflower is frequently grown in the same sites without applying traditional crop rotations. Differential lines for sunflower broomrape races A to F have been secured. The new broomrape races have been identified by researchers as races G and H. The question of whether the same broomrape mutations can occur in one year and affect the same countries remains unsolved. Several results of new broоmrape population emergences in some of the affected will be presented in the paper. A total of 390 genotypes were studied at four Romanian localities (Cuza Voda, Crucea-Stupina, Braila-Valea Canepii, and Tulcea-Agighiol) in 2014. At all four localities, a certain degree of sunflower broomrape infestation was observed in control hybrids and lines (Performer, LC-1093, LG-5661, and PR64LE20), which indicated the emergence of new populations higher than race H. The 390 studied genotypes had different reactions in all four localities. In 2015, 10 hybrids and controls were studied at five Romanian localities (Ciresu-Braila, Iazu-Ialomita, Stupina-Constanta, Topolog-Tulcea, and Viziru-Braila) and, according to the results, only hybrid Hy-7 was resistant in all localities. The results obtained from the three studied localities showed the emergence of new sunflower broomrape populations not controlled by gene for race H. Self-fertilization of hybrid Hy-7 produced the F2 generation in 2016. In 2017, broomrape resistance was studied at the infested (contaminated) plot at the All-Russian Research Institute of Oil Crops by the name of Pustovoit V.S. – VNIIMK in Rostov on Don. The plot was found to be infested by new broomrape populations originating from Russia, Ukraine, Romania, Turkey, and Spain. The obtained results showed an infestation degree in 17.1% plants of hybrid Hy-7, 35% in the F2 generation of Hy-7, control hybrids PR64LE25, LG-5580 and Donskoy-22 showed 19.4, 23, and 100% broomrape infestation, respectively. In conclusion, the plot contained broomrape populations which cannot be controlled by race H gene. According to the obtained results, a permanent change in variability of broomrape populations can be confirmed practically year after year. At present, new broomrape populations found at several localities are locally dispersed. Geneticists and breeders have to make joint efforts in further detailed studies of broomrape variability.