• Disease-resistant apple cultivar breeding
• Apple genetic resource research
• Apple cultivar testing
• Hybrid plum research and breeding
Disease-resistant apple cultivar breeding
The objective of the apple breeding programme is to obtain and select apple cultivars that are adapted to the climatic conditions of Latvia and the Baltic region:
- that have high quality fruits (incl. market quality, flavour, biochemical composition and storage),
- that are winter-hardy, productive, produce regularly, and are easy to cultivate (compact tree, minimum formation, minimum necessity for fruit thinning, holds the fruits well on tree),
- that have complex resistance to the major apple tree diseases common in Latvia (scab, canker, fruit rots, mildew), with various periods of consumption.
The work in apple breeding was carried out in several stages:
- Testing the hybrid pool that was acquired by Pēteris Upītis, selecting candidate cultivars (1995-1999).
- Taking over and testing the breeding material that was obtained by R. Dumbravs at "Iedzēni", incl. hybrid combinations with scab immunity genes Vf (Rvi6) and Vm (Rvi5) (1993-2016).
- LatHort apple breeding programme (1994-current). The programme uses the research results on genetic resource collection and the analysis results on gene markers, special attention is paid to fruit quality indices.
The programme includes scab resistance, columnar habit (Co) and anthocyanin colour donors.
Cultivars created during the breeding process have been tested also in other countriesof the Baltic region. Several of these cultivars have been approved as perspective in Estonia, Finland, Sweden; two cultivars have been registered in Belgium for cultivation in Ardennes mountain region. The cultivar 'Dace' deserves a special mention since it has been recommended for commercial cultivation in Latvia and is approved as perspective in Estonia.
Apple genetic resource research
The genetic resource study, description and descriptor adaptation to the regional climate conditions was started in Sweden as a joint project (1995, 1998-2000). The methods developed during this project have been applied to research in Latvia.
The genetic resource study and utilisation is significant for expanding the genetic base of apple breeding.
The genetic resource collection in Latvia maintains more than 100 apple cultivars of local origin that are well-suited for the regional climate conditions and have other valuable properties. Their successful use in breeding has been prevented by insufficient data availability. It is especially important to identify disease-resistance genes in the local cultivars and to find potentially new resistance sources. Within the scab research project, in collaboration with the Unit of Molecular Biology and Unit of Plant Pathology of the institute, a number of genotypes have been selected, and the research continues.
Another relevant issue is the rapid erosion of the genetic material due to the current changes in local orchards and farms . That is why expeditions for collecting genetic resources were organised in the early 20th century. Approximately 200 apple tree samples were collected and tested in the collection trial garden. A number of selected genotypes have been included in the genetic resource base collection. Collection, evaluation and description of genetic resources continue.
Apple cultivar testing
Although the assortment of the commercially cultivated cultivars in Latvia has relatively stabilised, horticulturists have expressed the necessity for new, better cultivars. Apple trees are one of the species to which, when introducing a cultivar, compatibility with local cultivation and market conditions is crucial. The greatest difficulty is to combine the cultivar winter-hardiness with good quality fruits and storage in the Latvian climate conditions.
The initial cultivar testing included apple cultivars from many countries, mainly from Latvia, Estonia, Sweden, Russia and Belarus. Research on the biological properties, fruitfulness and fruit quality is on-going. During exhibitions and Field Days, consumer and plant grower surveys are carried out.
Over the recent years, special attention has been dedicated to research on fruit quality and storage, which is influenced by the growing technologies, cultivar, fruit thinning intensity, harvest period, storage conditions. Within the framework of VPP-5 (2010-2014) project, guidelines on fruitlet thinning for the tested cultivars have been developed. Research on factors that influence fruit storage continues (SRP AgroBioRes project No. 2 (FRUIT) (2014-2020).
In the recent years, Latvian producers are showing increased interest in apples that are suitable for cider production. This interest has created a necessity for finding cultivars that are suitable for this purpose and are compatible with Latvian climate conditions. Research has been conducted on cultivars and hybrids that are potentially suitable for making cider, on the biochemical composition of their fruits, as well as their suitability for production.
Different clones of many older varieties still exist. It is necessary to select the clones that are recommended for cultivation. During the testing of 9 'Baltais Dzidrais' (‘White Transparent’) clones 5 different genotypes have been identified using gene markers. A field trial of their productivity and fruit quality continues.
Rootstocks are an important factor that has direct impact on the cultivar growth, productivity, fruit quality. Currently, 3 winter-hardy rootstocks of Finnish origin are being tested with 2 cultivars. A perspective rootstock MTT 4 has been selected.
Based on the research results, a number of new apple cultivars have been selected and recommended for further testing in commercial and organic orchards. These cultivars have been promoted in lectures and publications .
Diploid hybrid plum research and breeding
The research on the diploid hybrid plum gene pool in Latvia was started in 1982. A doctoral dissertation was developed based on the research. Within the framework of a joint project with Sweden, a research on plum genetic resources was carried out, developing principal characteristic descriptors: Project “Research and characterization of Prunus, Malus, Ribes genetic resources” (1997-2002).
Cultivars, introduced from Russia and Belarus, have been tested, resulting in the recommendation of the cultivar ‘Kubanskaja Kometa’ (Kometa) for commercial growing. It is currently the leading early plum cultivar in Latvia.
The hybrid plum breeding continues on a small scale, with the aim to increase their winter-hardiness and fruit quality.
REGISTERED CULTIVARS, AUTHOR OR CO-AUTHOR:
- Apple cultivar applications for registration in Latvia:
- ‘Lora’, ‘Auce’ (2020), ‘Felicita’, ‘Inta’, ‘Karlens’ (2016), ‘Lienite’, ‘Paulis’, ‘Saulesmeita’ (2017)
- Registered apple cultivars:
- ‘Dace’, ‘Gita’, ‘Edite’, ‘Ligita’, ‘Monta’, ‘Roberts’, ‘Baiba’, ’Uldis’, ‘Zane’
- Apple cultivars registered in Belgium:
- ‘Edite’ (COV Nº1804, Bruxelles 21/02/2011)
- ‘Ligita’ (COV Nº1803, Bruxelles 21/02/2011)
6 most important scientific publications:
- Ikase L. (red.) 2015. Augļkopība [Fruit Growing]. LV Augļkopības institūts, 544 lpp. (monography, in Latvian) http://fruittechcentre.eu/sites/default/files/2018-04/Auglkopiba.pdf
- Ikase L. 2015. Results of fruit breeding in Baltic and Nordic states. In: Proc. Of the 25th NJF Congress, Riga, Latvia, 16th-18th June, 2015; p.31-37. / http://llufb.llu.lv/conference/NJF/NJF_2015_Proceedings_Latvia-31-37.pdf (WoS)
- L.Ikase, G.Lacis. 2013. Apple Breeding and Genetic Resources in Latvia. Acta Horticulturae 976 (XIII EUCARPIA Symposium on Fruit Breeding and Genetics, Warsaw, Poland, September 11-15, 2011), p.69-74. http://www.actahort.org/books/976/index.htm]
- Ikase L., 2007. Evaluation of columnar apple hybrids on dwarfing rootstocks. Scientific Works of the Lithuanian Institute of Horticulture and Lithuanian University of Agriculture: Sodininkyste ir daržininkyste, 26(3). P.40-46. http://sodininkyste-darzininkyste.lsdi.lt/Documents/26(3).pdf
- Ikase L. and R.Dumbravs, 2004. Apple breeding for disease resistance in Latvia. Acta Horticulturae, 663, p.713-716. http://www.actahort.org/books/663/index.htm]
- Ikase L., 1998. Winterhardiness of diploid plums in Latvia. Sodininkyste ir daržininkyste: Horticulture and vegetable growing, 17(3), Babtai. pp. 135-142
5 most important popular science publications:
- Skrīvele M., Ikase L. 2013. Latvijas ābeles [Latvian apples]. R., „Jumava”, 136 lpp. (book, in Latvian)
- Kask K., L.Ikase. 2008. Lätis on palju uusi puuviljasorte [New Latvian fruit crop cultivars] // Maakodu, Nr. 12, 66.-68. (in Estonian)
- Skrīvele M., Ikase L., Kaufmane E., Blukmanis M., Strautiņa S., Ruisa S. u.c. 1999. Ilustrēts augļu koku un ogulāju šķirņu katalogs [Illustrated fruit and berry variety catalog]. Valsts Dobeles DSIS, Dobele, 323 lpp. (book, in Latvian)
- Ikase L., 1999. Ābolu avīze [Apple newspaper]. SIA Lauku Avīze, 64 lpp. (in Latvian)
- Ikase L., 1997. Iestādi savu plūmi [Plant your plum]. Izd. Dārzs un Drava, Rīga. 56 lpp. (book, in Latvian)