Effect of different nurseries and pot size on yield and long-canes collapse of ‘Sapphire’ raspberry

In Portugal, the production technology of raspberry long-canes allows growers to be competitive in the European market. However, in the production fields, plant collapses occur, associated with raspberry production techniques in nurseries, leading to productivity losses and plant death. Three experimental assays were carried out at the Portuguese southwestern coast to study the influence of several factors that can be on origin of plants collapse in the cultivar ‘Sapphire’. In assay 1, the influence of origin propagation nursery (The Netherlands – AD, BS and TY and UK – KS) and the exit date of plants from the cold storage to the field (July7, July 22 and August 12, 2020) in yield and plants collapse was studied. In assay 2, the influence of pot volume used during the vegetative growth of raspberry canes on the first year (1.8 and 4.7 L) and the exit date of canes from cold storage to field (same dates as assay 1) in yield and plants collapse was assessed. In assay 3, the presence/absence of Phytophthora spp. in root system and the amount of root starch reserves related with the plants physiological condition (collapsed, collapsing and not collapsed) was studied. The results showed that the most productive nursery is KS and canes that grow and develop in 4.7-L pots are more productive (≈2 to 3 t ha^‑1) and collapse less 25% than canes in 1.8-L pots. The best date for canes installation on field to produce raspberries in Portugal was July 22, since there were high yields and reduced flower and fruit abortion. The presence of Phytophthora spp. and low starch content in roots contributed to canes collapse, however, other factors that induce stress in canes during the production cycle must be considered, such as the high temperatures in summer (35 to 40°C), the excess of cooling hours in long-canes storage (more than 1000 h) and the conditions of cane growth and development in nurseries (cane density, pot volume, irrigation, fertilization, etc).