Temporary immersion systems for the mass propagation of sweet cherry cultivars and cherry rootstocks: development of a micropropagation procedure and effect of culture conditions on plant quality

Sweet cherry ( Prunus avium L.) varieties and cherry rootstocks are an important part of the fruit industry, and difficulties associated with mass propagation provide an opportunity for the use of temporary immersion systems (TIS). We show the establishment of culture procedures for four genotypes: the rootstocks Maxma-14 and Colt and the varieties ‘Van’ and ‘Rainier.’ The starting explants were internodal segments from seedlings kept in solid propagation medium (PM) (Driver-Kuniyuki Walnut (DKW) base supplemented with indole butyric acid, benzyl amino purine; ascorbic acid, myo-inositol, and agar). Segments were cultured under TIS for 14 d and led to whole plant generation after 30 d of culturing in solid rooting media, which depended on whether they are varieties or rootstocks. A 15-d acclimatization phase led to establishment in greenhouse. The efficiency of TIS was specifically analyzed for the two best PM-derivative media and compared to cultures using solid medium. A number of shoots ( P x ), biomass ( Q x ), and sucrose consumption (SC) were evaluated for these purposes. The results showed that Maxma-14, Colt, and ‘Van’ TIS cultures had improved performance in comparison to solid cultures, whereas ‘Rainier’ showed no differences. The number of immersions influenced all of the productive parameters ( P x , Q x , and SC), whereas genotype affected P x , and the time of immersion influenced SC. The best Q x and P x values were obtained with the rootstocks Maxma-14 and Colt, as well as the variety Van; these showed no hyperhydration. Physiological studies show that 14-d TIS-produced shoots represented an intermediate stage between solid-derived and adult plants, although the photosynthetic efficiencies of these materials revealed a lack of autotrophic ability at this point.