Tools for climate resilience in tree fruit I: Large-dwarfing rootstocks can alleviate sunburn damage in ‘Buckeye Gala’ apple

Suitable rootstock enhances apple tree resilience. In 2021, we studied ‘Buckeye Gala’ apple (Malus domestica var. Buckeye Gala) on nine rootstocks with contrasting vigor in Nova Scotia and British Columbia, Canada. Rootstock effects on vigor, yield and midday stem water potential were significant in British Columbia. After sustained heat events, the large dwarfing rootstocks Geneva 935, Geneva 4814 and Geneva 969 had lower ratio of sunburn fruits resulting in higher projected damage-free yield. We discussed how higher stem water potential and larger canopy volume supported by vigorous rootstocks contributed to alleviate heat stress and improve apple resilience to global warming.