Resistance of nectarine and peach-common almond hybrids by leaf curl

Abstract

Purpose. Isolation of genotypes of distant nectarine and peach-common almond hybrids with a low susceptibility to the peach curl pathogen.

Methods. The investigations were carried out in 2009-2013 on the breeding plots of the Nikitsky Botanical Garden. Susceptibility to the peach curl was studied by the method of VI Mitrofanov & AV Smykov using a nine-point scale, where 1 point means minimal damage, 9 points mean maximal damage. The source material was 48 forms of distant nectarine and peach-common almond hybrids created with the involvement of Persica vulgaris Mill., Persica vulgaris subsp. nectarina (Ait.) Shof., Persica mira Kov. et. Kostina, Persica davidiana Carr., Amygdalus communis L. characterized by a low degree of susceptibility to peach leaf curl under the field conditions on the natural infectious background. The nectarine varieties Rubinovyy 8 and Stark Sanglo, the almond variety Primorskiy, and the peach variety Podvoynyy 1 were used as controls.

Results. Of the 48 studied forms of distant hybrids 29 forms with a very low susceptibility to the peach curl pathogensusceptibility to the peach curl pathogen, eight forms with a low susceptibility, seven forms with a medium susceptibility, and four forms with high susceptibility were isolated. In other words, the majority (37 of 48, or 77 %) of the hybrids were found to be very low-susceptible or low-susceptible to peach leaf curl. These genotypes can be recommended for use in nectarine and peach breeding to create varieties with a low susceptibility to Taphrina deformans (Berk.) Tul. It was revealed that nectarine-almond hybrids of the first generation were hardly affected by peach leaf curl. In further crosses with nectarine varieties many hybrids of the second and subsequent generations retain a low susceptibility to this pathogen, and this trait is inherited.

Conclusions. The usage of common almond in nectarine breeding for resistance to leaf curl is beneficial, and breeding via distant hybridization within the subfamily Prunoideae Focke requires further research and development.