|Authors: ||L. Ikase, G. Lācis|
|Keywords: ||Malus × domestica, cultivars, collecting expeditions, disease resistance, tree characteristics, winter-hardiness|
Latvia is situated in the northern region of apple production with specific
requirements for winter-hardiness and length of the growing season.
Fluctuating winter and spring temperatures and relative abundance of precipitation add to the challenges.
The origin of apple cultivars in Latvia can be traced to back to Germany, Russia, Poland-Lithuania and Scandinavia.
Until the 20th century, open-pollinated seedlings were the only source of important local cultivars like ‘Baltais Dzidrais’ (‘Transparente Blanche’). In the 1950s and early 21st century expeditions were organized collecting and evaluating landraces, clones, amateur cul-tivars and the best chance seedlings.
Currently, the genetic resource collection in-cludes about 260 accessions of Latvian origin held at the Latvia State Institute of Fruit-Growing and the Pure Horticulture Research Centre, the base collection (109) is duplicated at both locations.
About 400 accessions are still being evaluated, prin-cipally for their use in breeding.
Controlled crosses were started in the 1950s, using cultivars best adapted to the Latvian climate and later involving donors of compact growth, columnar habit and scab resistance genes Rvi5 and Rvi6. Sev-eral of the resulting cultivars are grown commercially (‘Iedzenu’, ‘Forele’ and ‘Agra’) or are promising for commercial orchards (‘Eksotika’, ‘Daina’, etc.). The latest releases include scab resistant (Rvi6) cultivars ‘Dace’, ‘Edite’, ‘Gita’, ‘Ligita’, ‘Roberts’ and columnar apples ‘Inese’ (Rvi6), ‘Duets’, ‘Baiba’, ‘Uldis’ and ‘Zane’. The present breeding program is aimed at combining traits important for the development of competitive commercial apple production in Latvia – improved fruit quality and prolonged storage, complex resistance to fungal diseases (scab, Nectria canker, mildew, storage rots, etc.) and physiological disorders, regular yields with self-thinning fruits, easy tree habit and winter-hardiness.
Analysis of 129 apple accessions by 7 SSR markers was conducted to evaluate genetic diversity and clarify their relationships and possible parentages.
Results showed a high diversity of analyzed germplasm and ensured more accurate cultivar relationship information.
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