Evaluation of the production capacity of some plum cultivars grown in Romania

During a 14 years period (1982-1995), there were studied 30 plum cultivars and from them, 12 are presented in this paper. The production capacity is differentiated between varieties during the whole study period. The highest production capacity was recorded for: 'Centenar'(26.1 t/ha), 'Stanley' (22.3 t/ha), 'Pescarus' (19.9 t/ha) and 'Minerva' (19.5 t/ha). Low productions were obtained for: 'Vanat romanesc cl. 4' (7.9 t/ha), 'Early Rivers' (10.3 t/ha) and 'Gras ameliorat' (10.3 t/ha). For each variety, the fruit yield has very high variation coefficients (37.4 - 67.1 %) caused by a strong influence of the climatic conditions which are specific for every bearing year. By breaking up the percentage value of the fruit production into the component variances results that: genotype variance is responsible for 42.3 %, variance of the influence of the year is 47 %, variance of genotype x year interaction 7.6 % and the error variance is 3.1 %. Under the conditions of a variable climate from one year to another, there are some cultivars which have weight of the genetic influence for superior bearing ('Centenar', 'Stanley', 'Pescarus', 'Minerva', 'Blue Fre' and 'Tuleu gras'.