Susceptibility, heterosis and heterobeltiosis evaluations for fire blight resistance in pear

摘要

Fire blight is a devastating disease of Pomaceous trees that can cause death of the plants and leading to substantial crop losses. Controlled hybridization is widely used in breeding programs, due to the polygenic nature of fire blight resistance and the complexity of its mechanism. Right choice of parents appears to be the most significant criterion for obtaining genotypes that have desired characteristics. In this study 13 parental pear cultivars and 9749 F1 pear hybrids that were obtained from 36 different hybridization combinations were evaluated for fire blight resistance. Manifestation of heterosis and heterobeltiosis were also determined. As results of the study, ‘Magness’ is foremost as the most resistant variety, and followed by ‘Ankara’, ‘Moonglow’, ‘Kiefer’ and ‘Kaiser Alexandre’, respectively. ‘Conference’, ‘Williams’ and ‘Santa Maria’ were found susceptible to disease, while ‘Guz’, ‘Limon’, ‘Bursa’, ‘Akca’ and ‘Tas’ were highly susceptible to disease. Maternal parent was more effective for the transmission of fire blight resistance, when compared to pollinator parent. For this reason, it is suggested that disease-resistant varieties should be used as maternal parent. Heterosis was detected in 12 hybridization combinations. However, heterobeltiosis-focused approach was more effective for resistance breeding. For fire blight resistance, ‘Magness x Kaiser Alexandre’ and ‘Magness x Kiefer’ hybridization combinations that heterobeltiosis was determined are recommended.