Proper preconditioning, testing reduce winter damage to seedlings

Winter damage would be one of the most difficult challenge for many different woody plants. To prevent the winter damage and obtain higher economic benefits, different preconditioning methods such as using winter storage to help the first-year seedlings over winter have been developed.

However, appropriate preconditioning for the different progenies of the plus tree of forest seedlings within the same species, and different horticultural woody species and cultivars are not known well, said the Natural Resources Institute Finland (Luke) referring to a doctoral research.

The doctoral dissertation of Dongxia Wu, entitled Frost hardiness of Scots pine progenies and some woody horticultural cultivars under different preconditioning will be examined at the at the Faculty of Science and Forestry, on the 24th of September at Joensuu campus.

The growth of the trees in the boreal zone is based on the acclimation and adaptation of their annual cycle with the changes of the weather conditions during the four seasons.

MSc Dongxia Wu’s dissertation designed and implemented experiments to provide solutions for the appropriate precondition of economically important species in forestry and horticulture.

The study aimed to determine whether the pollination environments affect the FH of Scots pine progenies, whether the storage conditions affect the FH of woody horticultural species and cultivars, and whether a warm spell in winter affects the FH of pear cultivars.

The results suggest relatively small pollination effects on the FH in the whole-plant freezing test between Finnish and Ukraine populations.

The location of all seed orchards of the studied populations are suitable for production in Finland.

The results on the FH of different horticultural species and cultivars suggest that proper precondition is three weeks at minus 3 °C for apple and blueberry, and even shorter for blackcurrant. The FH of different cultivars of pear indicate that after a warm spell (3-4 and 16 days at +5 °C) followed by a cold period (5-7 days at minus7°C) some rehardening was found in the shoots but not in the buds.

According to the summarized results of this dissertation, FH testing can help to evaluate the preconditioning strategies to reduce the winter damage in the studied woody plants.

The results can be utilized in the production processes to improve the plant material delivered to farmers and forest owners.