Rose flower production and quality as affected by Ca concentration in the petal

The quality of cut rose flowers at the post-harvest stage is affected by th e susceptibility to Botrytis flower blight. This parameter may be related t o Ca concentration in the flowers. The objective of the present study was t o increase the Ca concentration in the stem and petals of roses in order to improve cut-flower post-harvest quality and to reduce the use of fungicide s. The effects of the solution composition, Ca, Na, K and Mg concentrations and night irrigation on Ca content in the cut flower and on its quality we re studied in greenhouse experiments in Israel and in the Netherlands. The main results and conclusions are: increasing the Ca concentration in the so lution from 0.5 up to 5.0 mmol.l(-1) increased Ca concentration in the flow er organs. Susceptibility to B. cinerea decreased with increasing Ca concen tration in the solution and was negatively correlated with Ca concentration in the diagnostic leaf and petal. Potassium and magnesium reduced Ca uptak e by the rose flower, and increased its susceptibility to Botrytis flower b light. Night irrigation enhanced the Ca concentration in the leaf but had n o significant effect on Ca concentration in the petal and on the susceptibi lity to Botrytis.