Tree growth, productivity and fruit properties of early ripening European plum ( Prunus domestica L.) cultivars

European plum is one of the most important temperate zone fruit species in the northern hemisphere. In the Republic of Serbia (RS), alongiside apple and raspberry, this species holds great significance in terms of production, processing, consumption, export, employment, and tradition. Therefore, continuous improvement of plum production is essential. Extending of harvest season and ensuring a prolonged presence of fresh fruits in the market are significant aspects of this improvement. This is achieved by developing new cultivars with earlier or later ripening time as well as cultivars that have improved storage capability. Generally, cultivars with an earlier or later ripening time fetch better price on the fresh fruit market. However, these cultivars, especially those with an early ripening time, have not been extensively introduced into the orchards in the RS. Keeping this in mind, we investigate tree vigour expressed as trunk cross-sectional area (TCSA), productivity (yield per tree and yield efficiency) as well as the most significant fruit physical (fruit and stone weight, flesh percentage, fruit dimensions and sphericity) and chemical properties (contents of soluble solids, total and reducing sugars, saccharose and total acids, ripening index, and pH value) of three domestic cultivars (‘Boranka’, ‘Čačanska Rana’ and ‘Valerija’) and three introduced cultivars (‘Katinka’, ‘Tegera’ and ‘Opal’), all of which are early ripening. The fruits were harvested from the end of the first to the end of the second decade of July. The obtained results showed significant differences among cultivars for all examined characteristics. Overall, the evaluated early ripening cultivars could be grown to some extent in commercial orchards in the RS.