NL: Looking for the ideal light recipe for multi-layer tulip cultivation

The light recipe to get better tulip foliage spread is largely clear, according to research by Plant Lighting and Proeftuin Zwaagdijk. However, in this research better leaf distribution did not result in less leaf tilting.

Modern tulip nurseries grow in multiple layers. Under lighting the young shoot grows into the lower and middle cultivation layer. The growth of the tulip is finally concluded under daylight on the upper cultivation layer. Multi-layer cultivation saves a lot of heating cost per m2 of surface area compared to conventional single-layer cultivation.

The problem is that tulip leaves often don’t spread well under lighting. Then there’s poor evaporation and cooling and this hampers the calcium supply to the developing cells. It is believed that this creates weak cells, causing leaf damage at a later stage (‘leaf tilting’). A solution to this common problem makes energy efficient multi-layer cultivation more accessible.

Research in the climate chambers shows that leaf spread appears to react strongly to the activity of phytochrome B. This photoreceptor may be controlled effectively with far-red light. Blue light also contributes to leaf spread, presumably through the photoreceptor fototropine. In addition more day length and light intensity also stimulate leaf distribution, whereby light intensity gives a saturation response. Better leaf spread, however, did not result in less leaf tilting under the climatic conditions that stimulate leaf tilting (high RH).

The questions that remain after this study are (1) how lighting can be even more effective and (2) is it possible to grow a ‘perfect tulip’ with that lighting strategy in a more favorable climate. Confirmation of that last question will make energy-saving multi-layer cultivation attractive for a wider group of tulip growers. In the meantime further research towards this has been granted.

This project is being financed by a group of tulip growers and Kas als Energiebron, the innovation and action program of LTO Glaskracht Netherlands and the Ministry of Economic Affairs.