Evaluation of the Production Traits and Fruit Quality of German Plum Cultivars

Abstract

Due to the substantial damage caused in Hungarian plum orchards by the spread of plum pox virus (PPV), high-yielding, often self-fertile German, Serbian and Romanian cultivars with better resistance to PPV have been introduced. Observations on growth characteristics, flowering and harvest time, yield potential and PPV resistance have been made in commercial plum orchards and gene bank collections since 2006, and these were supplemented with laboratory analysis on the fruit. German cultivars have spread widely in recent years, so it is particularly important to investigate the production value of these cultivars. In addition to field observations, a detailed analysis has been made over the last two years of the physical and chemical properties of the fruit of the most promising German cultivars (‘Topfive’, ‘Toptaste’, ‘Tophit’, ‘Topend Plus’ and ‘Jojo’) and of the control cultivars ‘Cacanska rodna’ and ‘Stanley’. The use of the German cultivars led to a lengthening of the harvest period, as fruit could still be harvested from ‘Topend Plus’ even in the middle of October. The onset of bearing was early for these cultivars, which had good yield potential, producing large numbers of buds not only on the spurs, but also on the long shoots. With the exception of ‘Jojo’ the cultivars exhibited greater initial vigour and the scaffold branches grew at a steeper angle, so greater care was required to form a favourable crown structure. The cultivar most resistant to PPV was ‘Jojo’, and ‘Topend Plus’ exhibited moderately severe leaf symptoms, while the other cultivars had only mild leaf symptoms. Among the cultivars included in the study, ‘Topend Plus’ and ‘Tophit’ had the largest fruit size, while ‘Toptaste’ had outstanding chemical properties, especially as regards the soluble solids and polyphenol contents.