Fattori che influiscono sulla conservazione in crescita rallentata di specie da frutto

Slow growth storage of shoot cultures is a very important tool for commercial micropropagation laboratories, as it allows to reduce the risk of contamination due to repeated subculturing, as well as to widen the offer of species and varieties and to better organize nursery production. The present study focused the attention on the slow growth storage of shoot cultures from 3 fruit rootstocks (GF677, Gisela 5® and Mirabolano 29C) and the kiwifruit (Actinidia deliciosa) cv Hayward. Different sucrose concentrations (30, 45 and 60 g l-1) and a sucrose/mannitol combination (30 and 15 g l-1, respectively) in the conservation medium were tested, with the aim to improve the quality of the stored plant material and to prolong the conservation time at 4°C and in the dark. Kiwifruit, Mirabolano 29C and Gisela 5® greatly benefited when the sucrose concentration in the conservation medium was increased to 45 or 60 g l-1, providing the conditions for a 18-month preservation of shoot cultures which maintained the potential of recovering fastly the proliferation activity when moved back to standard culture conditions. GF677 shoot cultures could be preserved up to 21 months, with no marked differences among the 3 sucrose concentrations in terms of shoot quality. Mannitol, used in combination with sucrose, had detrimental effects on the conservation of GF677 and Mirabolano 29C shoot cultures.