PHENOTYPIC DIVERSITY IN A SAMPLE OF BLACKCURRANT (Ribes nigrum L.) CULTIVARS MAINTAINED IN THE FRUIT BREEDING DEPARTMENT AT THE RESEARCH INSTITUTE OF POMOLOGY AND FLORICULTURE IN SKIERNIEWICE, POLAND

摘要

In this paper assessment of the phenotypic diversity in 40 blackcurrant (Ribes nigrum L.) cultivars was presented. The cultivars were from the breeding (working) collection, and originated from over a large geographical range. Bushes of the genotypes in the working collection were planted in autumn of 2004 in the Experimental Orchard in Dabrowice, near Skierniewice, belonging to the Fruit Breeding Department of the Research Institute of Pomology and Floriculture. Observations of 17 agronomical traits collected during the two years of 2007-2008 were analyzed. Two multivariate methods were used, i.e. principal component analysis (PCA) and cluster analysis (CA) using Ward's method and the square of the Euclidean distance. The first three PCs explained about 56% of the multi-trait variation among the cultivars, and the first two accounted for about 39% of the multi-trait variation. There was a high correlation of the two phenological traits, fruit size and firmness of fruit skin with PC1. This correlation represents the most important genetic common factor that could be called, "Ripening time driving fruit size and firmness". The PC2 was mostly correlated with number of basal shoots and fruit yield per plant. It represents the second common factor called, "Plant architecture affecting fruit productivity". Traits such as ripening time, fruit size and firmness, number of basal shoots, fruit yield per plant, as well as susceptibility to diseases and pests are the most discriminating pomological attributes that mainly contribute to overall phenotypic diversity of the blackcurrant cultivars. The cultivars were divided into five distinct clusters. Distribution of the cultivars in two PCs coordinates allowed us to find the existing rich diversity for the studied traits. Such diversity proves, that the characterized blackcurrant cultivar collection has high potential for specific breeding goals. The culfivars included in the diverse clusters could be promising parents with complementary levels of the most discriminating traits. They should be used for hybridization in order to obtain a high heterotic response. This response would substantially contribute to the blackcurrant breeding programs.