Climatic potential and risks for apple growing by 2040

Abstract

The impact of climatic change in 1971-2040 on the potential production areas and risks to nine apple cultivars (Malus domestica Borkh.) was studied over continental Finland using agro-climatic indices and gridded daily mean (T m ) and minimum temperatures from the Rossby Centre regional atmospheric climate model (RCA3) with SRES A2. Point data on daily minimum temperatures from 14 weather stations and low and high warming scenarios were also used. From the 1970's to the present day, the areas of successful maturing of fruits have strongly expanded northwards. It is predicted that in 2011-2040, the warming of climate will allow expansion of commercial production in the south-eastern lake area, and a wider selection of cultivars for home gardens up to latitudes 65-66°N. Risk of extremely low temperatures (T m < -26 °C) has reduced from 1980's to the present but may not reduce much more in 2011-2040. Risk to shoots from fluctuating temperatures in winter and spring is likely to increase under the high warming scenario, more in the south-west than in the south-east. Risk to trees from cold days (T m < -15 °C) with a concurrent thin snow cover is not predicted to increase. In the western inland of the country, below latitude 63°N, and in the south-western coast areas the frost risk during flowering may increase, especially in the early flowering cultivars. In order to adapt to and gain from the climatic change, breeding and testing targets should be modified within five years and they should include reduced sensitivity to temperature fluctuation in winter, late flowering, and frost tolerance of flowers.

Annual variation in sensory characteristics of seventeen apple cultivars

“…The global warming is already affecting plant phenology and cultivation, but effects differ depending on the plant and geographical area (Kaukoranta et al 2010, Sugiura et al 2013, Lehtonen 2015. With increasing level of DD5, the limit of commercial apple cultivation is moving northwards and the trend is estimated to continue (Kaukoranta et al 2010, Finnish Meteorological Institute 2014.…”

“…The annual crop has doubled since late 1990s, being now around 5 million kg (LUKE 2015a). Domestic apples are well liked and appreciated, because they are perceived as natural, fresh and clean, and have a low content of toxic residues (Malkki 2007, Seppä 2014.The grouping of domestic apple cultivars as summer, autumn and winter, or early, mid and late season cultivars, respectively, is based on the degree day (DD5), cumulative base temperature over 5 °C, requirements for harvest maturity (Tahvonen 2007, Kaukoranta et al 2010. Early season cultivars are important in Finnish tradition, while late season cultivars are commercially more important, as they usually have longer storage life.…”

“…Early season cultivars are important in Finnish tradition, while late season cultivars are commercially more important, as they usually have longer storage life. Seppä et al (2013a) showed that some late season cultivars maintain eating quality beyond the end of the harvest year even without controlled atmosphere storage.The global warming is already affecting plant phenology and cultivation, but effects differ depending on the plant and geographical area (Kaukoranta et al 2010, Sugiura et al 2013, Lehtonen 2015. With increasing level of DD5, the limit of commercial apple cultivation is moving northwards and the trend is estimated to continue (Kaukoranta et al 2010, Finnish Meteorological Institute 2014.…”

“…As late season cultivars are usually harvested by the mid-September, they benefit from warm autumns, such as is in 2009 and 2011. It is beneficial to the next year's crop if at least 100 DD5 degrees accumulate after harvest, to prepare the trees for winter (Tahvonen 2007, Kaukoranta et al 2010.The maturation of cultivars was monitored using horticultural methods such as starch iodine test, visual inspection and brix measurements (Brookfield et al 1997, Tahvonen 2007, Seppä et al 2012. Storage conditions were typical of Finnish apple production, as the availability of controlled atmosphere storage is very limited.…”

“…Thus, we assumed that the observed year effect is largely real. The maturing process in the orchard and consequently, the quality of harvest, is affected by local weather, cultivation practices and post-harvest factors (Hampson et al 2004, Thybo et al 2005, Tahvonen 2007, Kader 2008, Kaukoranta et al 2010. In other words, sensory and nutritional quality of fruits are established on the tree and influenced by orchard environment.…”