Early performance of three plum cultivars on different rootstocks in non-irrigated orchard

Growth and yield characteristics of three plum cultivars (Prunus domestica) ‘Elena’, ‘Tophit’ and ‘Cacanska lepotica’ grafted on seven different rootstocks were evaluated in the years 2010-2015. The tested material included St. Julien A as a standard, Jaspi-Fereley, Julior-Ferdor, St Julien 2, Pixy, MY-KL-A and Wangenheim seedling. Furthermore, ‘Tophit’ was assessed also on VVA1. The trees were planted in the experimental orchard of the Research and Breeding Institute of Pomology Holovousy in the Czech Republic. The orchard was established on medium fertile loamy soil in a non-irrigated plot in the autumn 2009. Planting distance was 5.5×2.7 m and the trees were trained to a central leader. The following characteristics were assessed: flowering intensity, yield, trunk cross sectional area (TCSA), crown volume, yield efficiency related to TCSA, yield efficiency related to crown volume, average fruit weight and suckering. We observed significant differences in growth and yields among the rootstock combinations in all of the cultivars. The most vigorous were MY-KL-A, St. Julien 2 and Jaspi-Fereley for all of the cultivars and also Julior-Ferdor for ‘Elena’ and ‘Tophit’. The least vigorous were Wangenheim seedling, Pixy and for ‘Tophit’ also VVA1. The production of suckers was generally at low level and dependent on grafted cultivar. All of the cultivars reached the highest yields on rootstock Jaspi-Fereley. The least productive were the trees on rootstock Pixy and in case of ‘Tophit’ also on VVA1. Similarly, the highest yield efficiency related to TCSA was on Jaspi-Fereley for all of the cultivars. Jaspi-Fereley had also a good yield efficiency related to crown volume and brought fruits of good weight. We concluded that Jaspi-Fereley is the best rootstock in non-irrigated orchards in our conditions for the first years of the growing period. Though it grows more than standard rootstock St. Julien A, it is precocious, highly productive and brings fruits of high weight.