Risultati in vivaio ed in campo ottenuti in Trentino su materiali clonali di Chardonnay sottoposti o meno a trattamento termoterapico in acqua

Grapevine propagation materials (buds of four Chardonnay clones, SO4 cuttings and grafted vines) subjected to thermic treatments in water prior to grafting and/or at end of the nursery cycle, were used for the experimental trial. Homogeneous lots of clonal material (200-300 buds or cuttings) were divided into groups and then subjected to three different kinds of treatment; thesis A: "termic bath" of buds and cuttings pre-grafting; thesis A +: the same as A thesis with additional use of with 8-hydroxyquinoline sulfate solution; thesis B: " termic bath " of grafted vines obtained from untreated control test, uprooted at the end of the nursery cycle. A control untreated thesis (Test) was added to the other thesis as comparison. The observations took place both in nursery (2009) and in vineyard (2010-2011).The controls in nursery concerned the steps of grafting and forcing (% of take), the plantation and the development of grafted vines, the evaluation of leaf color and chlorophyll contents through SPAD index (measuring device: Minolta 502) and the final yield of marketable grafted vines after uprooting. The agronomical assessments on the different thesis were made in a sandy soil vineyard, planted in June 2010 in Adige Valley (Trento province). For the comparison, two replicates of 25 grafted vines for each thesis and clone were planted in a randomized way. Other grafted wines of SMA130 clone on S.O.4 rootstock, belonging to different nursery lots, were added in the plantation as further comparison (tesi aziendale). During the years 2010-2011 it was assessed: the bud burst phase, the leaf color (July) and the weight of the wood after pruning in winter season.The results, obtained in the nursery and in the vineyard, showed an effect of the water heat- treatment on the % of nursery take after forcing, but not on the quality of the materials. In the first year after vineyard planting, it was registered, a slight delay in bud burst in the treated thesis without prejudicing the subsequent vegetative-productive cycle. No effect was found to be attributable to the different clone.The results confirm the validity of water heat-therapy in nursery practice, particularly where the risk of phytoplasmatic infection is high.

La moltiplicazione e la diffusione di materiale di propagazione della vite "sano" costituisce il presupposto fondamentale per garantire longevità e sanità ai vigneti. I tradizionali interventi di prevenzione messi in atto nei vigneti di piante madri non risultano spesso sufficienti a contrastare la diffusione di due gravi fitoplasmosi della vite, la flavescenza dorata (FD) e il Legno nero (BN), a causa del periodo di latenza della malattia e dell'elevata pressione dei vettori nell'ambiente di coltivazione. Da alcuni anni, particolarmente in Piemonte, si sta applicando anche su scala commerciale la termoterapia in acqua del materiale di moltiplicazione viticolo (Mannini e Marzachì, 2007; Mannini et al., 2009). Il trattamento a 50 °C x 45' applicato a marze di vite europea e talee da portinnesto sembra rappresentare l'optimum tra le esigenze di risanamento con termoterapia dagli organismi nocivi senza compromettere significativamente la vitalità degli innesti-talea cui il trattamento è applicato (Mannini e Bagnulo, 2007). Con questo lavoro si è voluto verificare l'effetto vivaistico di tale trattamento termoterapico in acqua effettuato prima dell'innesto oppure a fine ciclo, sulle barbatelle ottenute. La valutazione è avvenuta su materiali di propagazione clonali del vitigno Chardonnay e del portinnesto S.O.4 sia in vivaio (2009-2010) e quindi in vigneto (2010-2011) in una zona di fondovalle in Trentino.