In the Netherlands, the government and horticultural industry have agreed to lower the emission of nutrients to the environment. Until recently no drain water was reused in the cultivation of Cymbidium orchids as growers were allowed to discharge the drain water when a sodium level of more than 0 mmol / l was reached. As reusing drain water is a new phenomenon for Cymbidium, growers are now faced with a lack of knowledge on the effects of drain water reuse. Therefore a trial was started to investigate the effect of sodium accumulation on crop growth and flowering in two varieties of Cymbidium.
Different sodium concentrations are given while maintaining the EC at 0,8. These sodium treatments have a lower "nutritional EC" than the control treatment without sodium. As of February 2015 unusual symptoms in the leaves emerged at the two highest levels of sodium resulting in dead leaf tips / leaves. This is potassium deficiency, induced by the lower potassium concentration in the nutritional solution and by inhibition of the potassium uptake by a high sodium concentration. In the first year of cultivation, sodium accumulation had no effect on production as the flower stalks were already induced before the start of the treatments. Cymbidium is a perennial crop in which negative effects on production and quality take a long time to become visible, so the experiment will be continued into a second year of cultivation. To define more precisely the limit value for sodium, the highest dose of sodium has now been replaced by a treatment with an intermediate sodium concentration.
This research is funded by the Cymbidium growers in the Netherlands, Product Board for Horticulture and Top Sector Horticulture and Propagation Materials.