Forming innovative clonal rootstocks for varieties of the genus <i>Cerasus</i> Mill. (<i>Prunus cerasus</i> L.)

Abstract

The paper considers the main problems and solutions reported in literature concerning the formation and use of clonal rootstocks for cherry varieties in Russia, Europe and America. Examples of certain species are given (Cerasus fruticosa Pall., C.incisa Thunb., C.canescens (Bois) Erem. et Yushev, C.pseudocerasus Fr. Schmidt.), which were previously involved in hybridization for forming clonal rootstock of stone fruit crop. Following the performed research, the authors propose an approach to forming innovative vegetatively propagated rootstocks for species of the genus Cerasus Mill. (cherry, sweet cherry, Oriental cherry) based on distant hybridization and using germ preselection and cultivation in vitro. The obtained results confirm the importance of including previously selected sources and donors in the breeding process for forming clonal rootstocks with the following essential features: resistance to adverse environmental factors, low and high air temperatures, main harmful diseases – coccomycosis (causative agent Coccomyces hiemalis Higg.), monilial burn (Monilia cinerea Bon.), clasterosporiosis (Clasterosporium carpophilum Aderch.), and easy rooting of shoots (rooting ability). Such sources were isolated from collection representatives of cherry species: C.sachalinensis (Fr. Schm.) Komar. et Klob.-Alis. – 49 specimens, C.serrulata (Lindl.) G. Don. – 35, C.kurilensis (Miyabe) Kaban et Vorobiev – 43, (C.maximowiczii (Rupr.) Komar) – 34, C.lannesiana Carr – 4. The above forms, selected for breeding traits for the rootstock, were used for hybridization. Forms were isolated from F1 hybrid progeny from crossing them with sweet cherry (both forward and backward), and 25 F2 hybrids were obtained from all representatives. Germ cultivation in vitro enabled the breeding process to be accelerated by 2–3 years, and micropropagation of hybrid clones in vitro, transfer of microplants ex vitro and their subsequent cultivation in vivo under laboratory conditions enabled the necessary amount of breeding plant material (75 hybrids and 650 clones) to be obtained for further tests in a nursery.