More Sustainable Bulb Cultivation By Growing In Greenhouses

Disease-free starting material and a shorter life cycle could ensure that fewer pesticides are needed in the bulb cultivation. To do this, the starting material should be grown minimum one year in a greenhouse, tunnel or vertical farm, under the right conditions to maximize bulb growth. The Greenhouse Horticulture and Flower Bulbs Business Unit of Wageningen University & Research is researching the physiological aspects of such a new cultivation system for zantedeschia, narcissus, amaryllis and tulip.

Diseases and pests
In most bulbous species, it takes about five years to grow commercial bulbs from starting material. Due to the physiological nature of the bulbs, they need to be harvested, stored and re-planted every year. Unfortunately, this material re-circulation leads to spread and circulation of disease and pests, which in turns, increases the heavy use of pesticides. To break this circle, it is necessary to start clean (e.g. virus-free in vitro material), keep them clean during cultivation and shorten their life cycle to diminish circulation cycles. The result: fewer plant protection required, making cultivation more sustainable.

Maximize disease control and plant performance
Greenhouses offer the right conditions to maximize disease control and plant performance. However, the challenge will be to increase the photosynthesis capacity and carbon re-mobilization without disturbing the physiology of the crop. For example, some bulbs are day length sensitive. Therefore, a long day regime could increase the bulb biomass in the first months, but disturb the senescence signal. As a result, the bulb flowers multiple times, compromising the bulb biomass. This was observed in some lily cultivars.

Fundamental research
That is why WUR is investigating how the bulbs respond to cultivation in a greenhouse for four crops: zantedeschia, narcissus, amaryllis and tulip. Such as: what is the effect of different LED spectra and intensities on the photosynthesis capacity and carbon remobilization in those crops? And are there any molecular markers that could indicate in which physiological phase a flower bulb is (so that the cultivation strategy can be adjusted based on this, for example)?

This fundamental research answers the question of the physiological consequences of bulb cultivation in a greenhouse. This could eventually lead to a completely new cultivation system, in which bulbs, for example, are grown in a greenhouse, tunnel or vertical farm for one year, and then in the open field for another year. In that second year, the bulbs could be more robust and resilient to pest and disease, therefore less pesticides would be required.

'Fundamental system leap in flower bulbs'
The research 'Fundamental system leap in flower bulbs' is a PPS and is funded by Topsector Tuinbouw & Uitgangsmaterialen, KAVB, Anthos, Wageningen University & Research (WUR), Hobaho, Kapiteyn, Prins, Iribov, Dunamo Foundation, Agrifirm-GMN, BQ Support, Greenport Duin & Bollenstreek, Bollenacademie and Rabobank Nederland.​