In 2006-2008, yielding was determined and biometric measurement as well as chemical analysis was carried out for five Lithuanian sweet cherry cultivars, 'Agila', 'Seda', 'Vasare', 'Ventenue', and 'Jurgita', and two cultivars commonly grown in Poland, 'Ulster' and 'Burlat'. Trees grafted on Mazzard seedlings were planted in 2002 in the orchard of the Pozorty Experimental and Production Institute in the village of Łęgajny near Olsztyn. The highest mean yield for the tested cultivars was obtained in 2008, while the lowest was in 2007, when the highest ground frosts were recorded during the cherry blossoming period. During the three years of research, the highest mean yield for the Lithuanian sweet cherry cultivars was established for the 'Vasare' cultivar, which together with the 'Burlat' cultivar made a homogenous group of the highest values. The mean fruit weight of the Lithuanian cultivars was lower than in the case of 'Burlat' and 'Ulster', while the largest fruit amongst the Lithuanian cultivars were recorded for 'Jurgita' and 'Agila'. The chemical composition analysis of fruit revealed significant differences both between the cultivars and the years of the research. The fruits of the studied cultivars accumulated the lowest amounts of total saccharides and vitamin C in the coolest year under analysis, 2007. The highest mean of total saccharide content was recorded for fruit of the 'Vasare' and 'Seda' cultivars. Fruit of the 'Agila' cultivar accumulated the highest amounts of organic acids and vitamin C.

This study presents the influence of major weather factors during the blackcurrant blossoming period on the yields of the ‘Ojebyn’, ‘Titania’ and ‘Roodknop’ cultivars, cultivated in Warmia (Olsztyn). The study was conducted for five years (2003-2007). Among the factors analysed were the currant yield, the duration of the blossoming period, average daily air temperature, the number of days with frost at the height of 2 m and at the ground level, total rainfall during the blossoming period and the number of days with rainfall during the blossoming period. The statistical analysis of particular weather factors has shown that the number of days with frost contributed significantly to the yield of the fruit. A linear correlation analysis has shown that the yield of the three examined cultivars of blackcurrant depended on variable weather conditions during the blossoming period. The yield of the ‘Ojebyn’ cultivar was significantly correlated with the duration of the blossoming period, the number of days with frost and the number of days with rainfall. A significant correlation in the ‘Titania’ cultivar was found with the number of days with frost and with the total amount of rainfall during the blossoming period. The fruit yield from the ‘Roodknop’ cultivar in the five-year period under study depended only on one variable: the duration of the blossoming period. The highest yield was obtained from the ‘Titania’ cultivar.

No abstract