LATVIA UNIVERSITY OF AGRICULTURE - Latvijas ...

PERSPECTIVES ON TRUFFLE CULTIVATION IN LATVIADiāna Meiere, Antra Balode, Christina Wedénphysiography of Latvia and its neighboring areaswas formed, to a large degree, during the Quaternaryperiod and the Pleistocene ice age. The parent materialfor Latvian soil formation are the Quaternary deposits,among them glacial tills (moraines) are prevailing(Kārkliņš et al., 2009) and glaciolimnic deposits arethe main source of calcareous soils. The Nationalsoil classification system used in Latvia is not alwayseasily comparable to the international systems.According to the international soil classificationWRB (World Reference Base for soil resources),Latvian soils belong to Phaeozems and Stagnosols(Zemgale Plain), soils in uplands usually are Luvisols,Cambisols, Gleysols as well Histosols. In the forestssoils are Arenosols, Podzol, Umbrisols, Stagnosols,Albeluvisols and Cambisols (Nikodemus et al., 2008).In the national classification system there are severaltypes of soil with high content of carbonates, whichmeans that soils are neutral or slightly alkaline andare favorable for the truffle development. Such soils(Sod calcareous soils in national classification system)cover approximately 5.5–6.0% of the total area ofagricultural land; in several parts of Latvia (central partof Latvia in vicinity of Jelgava, Bauska, Dobele and toa lesser extent – around Tukums) they comprise about50% of the total area of agricultural land (Kārkliņš etal., 2009). There are smaller territories of such soils inRietumkursas Upland (western part of Latvia) as wellas in other parts of Latvia where limnoglacial depositsare found. In the vicinity of Kandava and Sigulda, veryshallow carbonatic soils of Rendzina type are found.Climate in Latvia and its suitability for the trufflecultivationEvaluation of the climatic characteristics is veryimportant in finding the most favorable areas for thetruffle cultivation in Latvia. It is believed that theclimate is the most important limiting factor for thedevelopment of T. aestivum cultivation in Europe,especially in the northern countries (Chevalier, 2010).A long and mild autumn is crucial for the propermaturation of T. aestivum fruitbodies throughout theharvest season. If the soil freezes early, the truffleharvest also ends for that season.The Latvian climate is humid Europeancontinental with the maritime influence of the BalticSea. Summers are warm, and the weather is mild inspring and autumn, however, winters could be fairlycold. The mean temperature of the year is 4.3–6.6 °C.Precipitation is distributed throughout the year withthe heaviest rainfall in July. Annual precipitationranges from 500 to 837 mm with the maximumrainfall during the summer and autumn months(70% from April till October), which is favorablefor the development of most truffle species (Table1). The mean daily temperature in January is from-2.6 °C (coastal areas of the Baltic Sea) to -7.5 °C(more continental parts of the country); in July from+16.5 °C to +17.6 °C which is equivalent or even a bithigher than for T. aestivum and T. borchii producingareas in Sweden, Denmark and the United Kingdom(Hall et al., 2007). Accumulated degree days show thelength of the vegetation period for plants, and sincetruffles are closely connected with their host plants,good conditions for the host trees might also meangood development of truffles. Despite that Latvia isa northern country, the number of annual sunshinehours is relatively high. As seen in the summary ofthe climatic data given in Table 1, the only parameterwhich differs significantly between Latvia and edibletruffle-producing areas is a comparatively low meanair temperature in January. It could be a limiting factorfor the development of truffle species with a moresouthern distribution, but a stable snow cover mightalso reduce the impact of the cold.Suitable host tree speciesTruffles are mycorrhiza-forming fungi, and growin a symbiotic association with, usually arboreal,plant. Most truffle species can form symbiosis andgrow with several tree species, although some ofthem are considered better host trees than others. Forthe cultivation purposes, choosing tree seeds fromspecies well adapted to the local climate is important.Comparison of climatic data of edible truffle Tuber spp. – producing areas and LatviaTable 1Truffle speciesAnnualprecipitation(mm)Mean dailytemperature insummer, July(°C)Mean dailytemperature inwinter, January(°C)Accumulateddegree days(>10 °C)AnnualsunshinehoursTuber melanosporum 1 563-1443 19.2-24.6 1.6-9.2 1115-2341 1704-2837T. magnatum 1 589-1545 21.3-24.6 2.4-5.0 1349-2009 1989-2388T. aestivum 1 514-1045 15.2-26.2 –1.1-12.5 489-2009 1375-2837T. borchii 1 514-1045 15.2-26.2 0.1-12.5 489-3125 1375-2388Latvia 2 500-837 16.5-17.6 –7.5- –2.6 1700-2100 1680-19001Data from Hall et al., 20072Data from Kalniņa, 199574 Research for Rural Development 2012