In Gran Bretagna le tradizionali coltivazioni di mele sono minacciate dall’aumento delle temperature che porta i ricercatori a studiare il modo di impiantare varietà provenienti dalla Nuova Zelanda e dal Giappone. Ne parla The Guardian in un articolo di Helena Horton.

Apples such as pippin or the the ancient nonpareil, grown in Britain since the 1500s, are struggling in the changed climate because there are not enough “chilling hours” for the trees to lie dormant in winter and conserve energy for growing fruit. Scientists at Royal Botanic Gardens, Kew, are planting 40 apple trees, a third of which are heritage varieties that once grew in its Georgian kitchen gardens. Another third are new varieties bred to need less cold over winter, and the final third are from warmer countries including South Africa. The varieties will be compared to see which has the best crop in London’s warming temperatures.

Tuttavia non è ancora possibile affermare che le nuove coltivazioni di importazione troveranno le giuste condizioni per crescere e produrre.

However, it is not certain that these new varieties will be the solution: “We could find out that we don’t get a dry enough winter for these varieties. So this is why it’s an experiment, because South Africa doesn’t have the wet weather that we have. So it’s going to be whether they’ve got low chill hours and can cope with the amount of rain.”

Sono alcuni anni che ci si interroga sul cambiamento climatico e le sue conseguenze sui frutteti inglesi. Ne parlava già nel 2018 questo documento dell’University of Reading che riferiva di un’importante sperimentazione a lungo termine, avviata alla Brogdale Farm nel Kent e finanziata dal National Fruit Collections Trust, che aveva lo scopo di valutare gli impatti dei cambiamenti climatici in atto sulle colture.

Experiments at the National Fruit Collection, at Brogdale Farm near Faversham, are taking place in a new 0.6 hectare facility under polythene covers. Trees of more than 15 varieties of apple were established in 2014 and have been grown in modified environments since last winter. Traditional UK, such as Cox’s Orange Pippin and Bramley, and newer international varieties, such as Fuji, Gala and Golden Delicious, are included in the study. The experiments are planned to continue for at least a decade to monitor long-term changes and factor in year-to-year variation in ambient temperatures.

Orchard Notes riporta i risultati di uno studio intitolato 60 anni dopo – Effetti del cambiamento climatico sulla fenologia degli alberi – Un caso di studio utilizzando il frutto del pomo, pubblicato su Horticulturae nel gennaio 2022 (link al documento completo). La ricerca ha identificato alcune delle probabili conseguenze degli ultimi 60 anni di cambiamenti climatici, utilizzando i dati raccolti da un frutteto di ricerca a Klein-Altendorf, vicino a Bonn, nella Germania occidentale.

The statistical analysis by Achim Kunz and Michael Blanke, both of the University of Bonn, assesses data collected over the 60 year period 1956 to 2017. Some of their findings are rather concerning, with potential implications for commercial apple growers, but also for small-scale home or allotment orchardists, in Europe and maybe the Northern hemisphere in general.

Secondo lo studio questi mutamenti climatici portano anche come conseguenza un aumento del rischio delle gelate tardive, tanto deleterie per le produzioni agricole.

The combination of stronger increase in winter temperatures (by +1.2 °C) than in the summer (air +1.0 °C) with advanced bud break and −0.3 °C lower minimum temperatures in April during flowering resulted a continued risk of a late frost, as experienced in 2017. The strongest climate change effect, i.e., 11–14 days advanced flowering (in apple and pear) highly correlated (R2 −0.7) with the March/April temperature.