Browsing by Subject "http://www.yso.fi/onto/yso/p12645"

Experiments with outdoor viticulture were started in Southeast and Southwest Finland in the 1930s. Our rather short growing season and lack of suitable varieties have hindered professional extensive outdoor viticulture. The grapevine varieties bred for northern conditions and the forecasted prolongation of our growing season will likely lead to viticulture in Southern Finland within the next few decades. Soil temperature has an important influence on the survival and growth of the grapevine. Soil temperature is affected by air temperature, cultivation site, soil cultivation, vegetation, soil type and wintertime snow cover. The aim of my Master`s thesis was to measure soil temperatures of grapevine sites and, based on the reults, to estimate the optimal planting depth of a grapevine in Southern Finland. The effect of changes in air and soil temperatures on grapevine growth and development in Tuusula, Vehmersalmi and some Central European localities was also followed. Measurements revealed that soil temperature was at its lowest in March, when in Tuusula at a depth of 20 cm it decreased to -0.7ºC and at a depth of 60 cm to 2.0ºC. Compared with soil temperatures measured by the Finnish Meteorological Institute in other localities, the temperatures at a depth of 20 cm in Maaninka fell to -0.8ºC, in Juva to -0.3ºC and in Jokioinen to -1.6ºC and at a depth of 50 cm in Maaninka to 0.0ºC and in Jokioinen to -0.3ºC. In Tuusula, the annual average soil temperatures at a depth of 20 cm was 6.0ºC and at a depth of 60 cm 7.9ºC. In regression analysis, strong correlations (r2 = 0,497 - 0,684) were obtained between air temperatures measured at grapevine sites at a heigth of 150 cm, ground surface temperatures and soil temperatures measured at a depth of 20-60 cm. In the winter months of December, January, March and April, when the snow cover remained thin, the correlation between snow cover and soil temperatures was weak. The soil temperature during the coldest winter month at a depth of 20 cm fell to slightly below 0.0ºC, at a depth of 40 cm it remained at about 0ºC and at a depth of 60 cm it remained at 2ºC. Based on this, the depth of 40-60 cm can be regarded as the optimal planting depth for grapevines in Southern and Eastern Finland. At this depth, the freezing risk for roots in winter is minor, and in spring solar radiation quickly raises the soil temperature. In 2002-2007, the grapevine growing season had begun in Tuusula as a weeping at the earliest on April 24th. The buds began to swell and break earliest on May 1st. The flowering began earliest on June 16th and lasted for about two weeks. The earliest harvest began on September 14th. From the start of flowering to the start of harvest, the time elapsed was 75-92 days. Growth slackened as the soil temperatures fell and ceased altogether in September. In Central Europe, the weeping of the grapevines starts because of higher air and soil temperatures a couple of months earlier than in Southern Finland, but the flowering begins no more than one month and the harvest only 2-3 weeks earlier. The quicker growth and development in the north can be explained by the quicker warming of the air and soil, the longer days and the abundant supply of light in early summer.