Assessment of self-(in)compatibility in sour cherry genotypes developed at Fruit Research Institute, Čačak

Abstract

In sour cherry (Prunus cerasus L.), as in other species of the Prunus genus, the phenomenon of gametophytic self-incompatibility occurs. Basically similar to another Rosaceae species, sour cherry GSI is quite complex due to its tetraploid nature and the presence of pollen-part and stylar-part mutants that cause genetic changes at the S-locus. The phenomenon implies self-incompatible, partially self-compatible and self-compatible reproductive behavior of cultivars, as well as requirement for pollenisers in commercial orchards. Self-(in)compatibility status of sour cherry cultivars/selections realized at Fruit Research Institute, Čačak [‘Šumadinka’ (‘Köröser Weichsel’ × ‘Heimanns Konserven Weichsel’), ‘Sofija’ (‘Čačanski Rubin’ × ‘Heimanns Konserven Weichsel’), ‘Nevena’ (‘Köröser Weichsel’ × ‘Heimanns Konserven Weichsel’) and ‘GV-6’ (selected from natural population in the Čačak vicinity)] was examined over two years, and compared to standard ‘Heimanns Konserven Weichsel’. Self-pollination experiment in the field was conducted, as well as monitoring the parameters of pollen tubes growth efficacy in vivo by fluorescent microscopy (pollen tubes number and kinetics, fertilization percentage and presence of incompatible pollen tubes), and fruit set recording. In the pistils of ‘Nevena’, pollen tubes ended their growth predominantly in the upper part of the style, with sporadically penetrated tubes in the middle style. Pollen tubes kinetics was more efficient in the styles of other genotypes ‒ they were in the micropyle already on the 3rd day, and in the nucellus of the ovary on the 6th day after pollination (‘Šumadinka’, ‘Heimanns Konserven Weichsel’ and ‘Sofija’). According to fertilization percentage and fruit set, ‘Nevena’ could be undoubtedly classified within self-incompatible cultivars (both parameters were 0.00%, in both seasons), whereas ‘Šumadinka’ (17.92%; 16.31%, respectively) and ‘Heimanns Konserven Weichsel’ (18.75%; 17.50%, respectively) behaved as self-compatible. Showing relatively high values of fertilization percentage (21.05%; 23.18%, respectively), but lower values of fruit set (11.57%; 7.24%) after selfing, ‘Sofija’ and ‘GV-6’ could be classified as partially self-compatible genotypes.