Several experiments were carried out to study the influence of growing season on fruit yield and quality of greenhouse melons grown in nutrient film technique. As compared with spring, the plants grown in summer exhibited faster growth and development, but produced fewer fruits of larger size and poorer quality due to lower sucrose content. In summer the fruits ripened within 30-35 days after anthesis, that is two weeks less than in spring. Higher average temperature was likely responsible for earlier fruit ripening in summer, as in both seasons the fruits were picked after 450-500 degree-days (base temperature of 12°C). The reduction of sucrose content in summer-grown fruits was accounted for by insufficient carbon supply from source leaves and inadequate synthesis of sucrose, as suggested by the determination of leaf photosynthesis and the activity of sucrose phosphate synthase in the fruit flesh during the final stages of fruit development. Lower radiation was likely responsible for reduced photosynthesis in summer with respect to spring, since growing season did not affect leaf stomatal conductance, water and mineral relations, and chlorophyll concentration. In both seasons, increasing the macronutrient concentration of the recirculating solution enhanced plant mineral uptake, but it did not influence significantly fruit yield and quality. In other experiments, we investigated the possibility to improve fruit quality in summer crop by artificial NaCl salinization (50 mM) or by cooling the recirculating nutrient solution in order to maintain a constant temperature of 25°C in the root zone, instead of fluctuating temperatures from 20-22 to 38-40°C in the control. Salinization increased only slightly the concentration of sugars in the fruits and, in summer, promoted the occurrence of flesh vitrescence. Fruit yield and quality were not affected by root cooling, which instead increased the plant's susceptibility to root death.
|Pages (from-to)||213 - 219|
|Number of pages||7|
|Publication status||Published - 2001|
All Science Journal Classification (ASJC) codes
Pardossi, A., Malorgio, F., Incrocci, L., Tognoni, F., & Campiotti, C. A. (2001). Recirculating nutrient solution culture of MELON (Cucumis melo L.): Physiological and cultural aspects. Acta Horticulturae, 554, 213 - 219.