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Le tecniche di moltiplicazione, l'uso del portinnesto, la micropropagazione: molti gruppi di ricerca in Italia sono attivi nel miglioramento dei sistemi di propagazione del nocciolo. Avanzano anche i lavori per lo sviluppo del programma di certificazione genetico sanitaria, su base volontaria, del materiale vivaistico che, alla luce del mutato quadro normativo europeo, dovrebbe essere operativo entro la fine del 2017.

Il Progetto VITROFLOR si propone di intervenire nella filiera produttiva di piante ornamentali (floricole e da vivaio) prendendo in esame la parte propagativa delle nuove accessioni, individuate a seguito di programmi di miglioramento genetico e/o di selezione, ed intervenendo, in particolare, nell’ottimizzazione delle procedure di micropropagazione e conservazione in vitro. La propagazione su larga scala è spesso un elemento condizionante lo sviluppo commerciale di una novità vegetale, influendo, a volte consistentemente, sui costi di vendita. In tale senso, la micropropagazione è particolarmente indicata per il comparto ornamentale che riesce a sostenerne i costi di produzione ed a trarne vantaggio economico. Le istituzioni di ricerca coinvolte in questo progetto sono state incaricate dalla Ditta proponente (Viavai Piante Battistini, Cesena) di studiare ed approfondire alcuni aspetti della coltura in vitro che potrebbero, una volta a regime, rendere più competitivo il sistema di moltiplicazione, a vantaggio sia della ditta di propagazione, sia degli ibridatori che ad essa si affidano per la fornitura di materiale omogeneo e sano. La tecnica, inoltre, permette di programmare la produzione di piante nell’arco dell’intera stagione vegetativa, svincolandosi dai problemi connessi con la stagionalità della propagazione tradizionale. I partners del progetto utilizzano materiale originale fornito da ibridatori e, tra le attività previste, riporteranno in questo lavoro i risultati intermedi relativi alla fase di sterilizzazione, al contenimento delle batteriosi durante la coltura, ai metodi per ottimizzare le rese di proliferazione e di radicazione e alla conservazione in crescita rallentata (a basse temperature) del materiale stock.

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.

The study focused on an economically-important ornamental outdoor shrub, Nandina domestica, with the aims to (i) optimize an effective in vitro conservation method, and (ii) develop a cryopreservation protocol for shoot tips by the PVS2 vitrification and droplet-vitrification techniques. For in vitro conservation of shoot cultures, the tested parameters were sucrose content in the storage medium (30, 45, 60 g/L) and storage temperature (4 °C or 8 °C). Cryopreservation was performed by applying the PVS2 vitrification solution, in 2-ml cryovials or in drops over aluminum foil strips, for 15, 30, 60 or 90 min at 0 °C, followed by the direct immersion in liquid nitrogen of shoot tips. Results show that N. domestica shoots can be conserved successfully for 6 months at both the temperatures tested, especially when 60 g/L sucrose is used in the storage medium. However, conservation at 4 °C showed to be more appropriate, as hyperhydricity was observed in post-conservation of shoots coming from storage at 8 °C. As for cryopreservation, a daily gradual increase of sucrose concentration (from 0.25 to 1.0 M) produced better protection to the samples that were stored in liquid nitrogen. Indeed, with this sucrose treatment method, a 30-min PVS2 incubation time was enough to produce, 60 days after thawing, the best recovery (47% and 50%) of shoot tips, cryopreserved with PVS2 vitrification and droplet-vitrification, respectively.

In vitro culture plays a prominent role in the selection, propagation and conservation of ornamental plants, fulfilling increasing market demands in terms of genetic and sanitary quality of the produced material. The present research is ongoing, aiming to optimize the conservation in vitro of selected lines of Anthurium, Ranunculus and Carex by slow growth storage. The study evaluates the effects of different storage temperatures (6 and 10°C, in dark conditions) and sucrose concentrations (30 or 60 g/L) on the maximum time of conservation and the regrowth potential of shoots in post-conservation. Data recorded periodically during the conservation period consisted of the survival and quality evaluation of shoots. Relative Growth Rate (RGR index) was also evaluated during both the storage period and in post-conservation, and compared to shoots in standard culture conditions. The species showed a marked growth reduction under the imposed climatic conditions. Although the stored material showed symptoms of oxidation (Anthurium) and etiolation (Ranunculus), a good regrowth potential was observed after the storage. Regardless of medium sucrose content, better storage condition for Anthurium was at 10°C. Differently, Ranunculus adapted well to both the tested temperatures, showing a superior quality of shoot cultures when stored on the medium supplemented with 60 g/L sucrose. Maximum conservation time was 8 months (Anthurium) and 9 months (Ranunculus). A similar experiment is presently in progress with a shoot culture line of Carex.