Productivity of three rose cultivars ( Rosa hybrida) trained in a ‘vase-shaped’ form and grown in a commercial glasshouse in a Mediterranean environment

Abstract

A survey was conducted over 12 months to determine productivity and compare the relationships between the different shoot types of three rose cultivars of different ages. The plants were trained in a ‘vase-shaped’ architecture. Data were collected on 1 year-old ‘Sonia’, 8 year-old ‘Gabrielle’ and 7 year-old ‘Kardinal’. The ratio of basal shoots : branches : shoots (flowering and non-flowering shoots) over one season was 1 : 2 : 7 (Sonia), 1 : 3 : 8 (Gabrielle) and 1 : 3 : 11 (Kardinal). Of the shoots produced, 44% (Sonia), 29% (Gabrielle) and 19% (Kardinal) were marketable stems and the remainder were either unmarketable (discarded after harvest) or blind shoots (not harvested). A high number of unmarketable stems occurred in summer and were associated with high temperatures and the marketing requirement to harvest the entire crop over 2–3 days. The majority of blind shoots were <5 cm long and formed on the upper half of shoots or branches and in the upper half of the leaf-canopy. Although harvested stem production was positively correlated with the number of branches, increasing branch numbers does not necessarily increase the number of harvested stems in direct proportion. This has implications for plant management and harvesting techniques.