Study of Density of Raspberry Fruits in View of Mechanized Harvesting

Abstract

The paper discusses the possibility of combining large-fruits and density of raspberries as one of the main and decisive limiting indicators of the suitability of varieties for mechanized cultivation and further harvesting, as well as for long-term transportation to the consumer. The objects of research were 20 raspberry varieties and 15 elite forms from controlled crossings and populations from free pollination. The annual assessment of the density of raspberries was carried out at the collection and selection plots during the period of active fruiting (June-July-August) 2019-2020. From each variety sample, 10 berries were taken at full maturity. The berry crushing force was determined using the fruit test device. The climatic conditions of the study periods were rich in contrast, which indicates the instability of climatic factors of the summer growing season. This made it possible to fairly objectively evaluate the collection and breeding material in terms of the size and density of raspberries. Assessing the crushing force of collection and elite forms of raspberries made it possible to identify varieties having the increased fruit density. Rannyaya Zarya, Lyachka and Lazarevskaya have a relatively large (3.5-4.5 g) and dense berry with a crushing force of 7.6-8.4 N. The interesting elite forms are 9-58; 9-27; 9-20 with a berry mass of 3.8-4.0 g and a crushing force of 7.3-9.7-N. The crushing force of fruits of these elite forms during the study period was not lower than 5.0 N, but sometimes it was significantly influenced by soil and air moisture, which negatively affected the commercial qualities of berries.