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Abstract  The present study reports on the kinetics of nutrient utilization during in vitro flowering of Spathiphyllum in air-lift bioreactor cultures. Levels of electrical conductivity (EC), anions and cations, pH, ethylene, sugar content and photosynthetic enzymes were determined in bioreactor cultures of both flowering (FPs) and non-flowering (NFPs) plantlets over a growth period of 12 weeks. A decrease in ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity with a corresponding increase in phosphoenolpyruvate carboxylase (PEPcase) activity occurred during floral induction of Spathiphyllum in vitro. Sucrose concentration decreased significantly in FPs, while no changes in glucose, fructose and total sugars were observed in both FPs and NFPs up to 8 weeks of culture. There were significant variations in mineral nutrient utilization between FP and NFP cultures. These results provide an insight to the physiological processes involved in inflorescence formation in Spathiphyllum. [ABSTRACT FROM AUTHOR]

Abstract  Stems of chrysanthemum (Chrysanthemum morifolium Ramat.) cv. Maghi were harvested when half of the buds showed colour and were put in distilled water at 21�C. Flowers showed visible senescence symptoms after 12–15 d. Reactive oxygen species (ROS) concentration and lipid peroxidation increased from young floret stage to the senescent stage. Activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD) and catalase (CAT) showed uniform increases from young floret through to the mature stage and thereafter, declined. Among the SOD isoforms, Fe-SOD and Cu/Zn-SOD were induced during the onset of senescence. Similarly different isoforms of APX and glutathione reductase (GR) also appeared during the senescence process. The capacity of the antioxidative defence system increased during the onset of senescence but the imbalance between ROS production and antioxidant defences ultimately led to oxidative damage. It is proposed that a decrease in the activity of a number of antioxidant enzymes that normally prevent the build up of free radicals can at least partially account for the observed senescence of chrysanthemum florets. [ABSTRACT FROM AUTHOR]