Guide for Authors

Bromeliad growers report severe leaf quality problems for Aechmea cultivars grown under commercial greenhouse conditions. In this research, a leaf damage ‘sensitive’ and ‘insensitive’ A. cultivar were compared for their C-metabolism and hydrophysiology under these greenhouse conditions. Stomata opening index indicated CAM (Crassulacean acid metabolism) for both cultivars, with 45–50% open stomata around 4:00 a.m. and 5–10% in the afternoon. Malic and citric acid were the major organic acids present in the leaves, with diurnal malic acid accumulation during the night. The leaf damage ‘sensitive’ cultivar showed higher malic acid accumulation than the ‘insensitive’ cultivar (200 μmol/gfw versus 170 μmol/gfw). Leaf osmotic potential and turgor pressure were linked with diurnal malic acid fluctuations: organic acid accumulation during the night generated high leaf turgor pressures (up to +0.86 MPa).A leaf damage sensitivity test was designed and confirmed previous experiences of several bromeliad growers. Both cultivars showed higher leaf damage percentages (98 and 78%) when leaf malic acid accumulation was high. We attribute this elevated sensitivity to lethal turgor pressures and consider them to be caused by the water capturing mechanism generated by high organic acid accumulation. Under current greenhouse conditions, this water capturing mechanism can be disastrous for plant leaf quality. Especially, under high relative humidity, hindering plant transpiration and stimulating water uptake by dew formation, leaf quality could be endangered.