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Project

Anomalies in the leaf development of Vriesea and Guzmania

Guzmania and Vriesea (Bromeliaceae) are tough plants, resistant to drought and scarce nutrient supply. Their leaves are arranged into a ‘tank’ which catches and stores water and debris, and are covered by trichomes capable of absorbing water and nutrients from the tank solution. Because of these adaptations, unique for the Bromeliaceae family, they thrive as epiphytes growing on trees in South-America. However, when they are cultivated as ornamental plants in Belgium and the Netherlands, breeders and growers in experience severe losses due to two phenomena: ‘leaf holes’ in Vriesea and ‘tubing’ in Guzmania. In this PhD project, both problems were shown to be caused by greenhouse conditions disturbing the unique water– and nutrient uptake mechanisms of Bromeliaceae.

As a form of necrotic spot formation, leaf holes formation renders up to 50% of ornamental Vriesea unfit for sale. All Vriesea cultivars can develop leaf holes, but are susceptible to a varying degree. The formation of leaf holes in Vriesea was found to be correlated to excessive nutrient application. Combined with the efficient trichome-mediated uptake and accumulation of nutrients by Tillandsioideae, this likely creates mineral toxicities in the leaves. Cultivar susceptibility to leaf holes formation might be explained their ability to limit the unselective trichome-mediated nutrient uptake. While application of specific nutrient solution compositions leads to a higher number of affected plants, no single macro-or micronutrient could be identified as the main factor in leaf holes formation. Since a considerable variety in the percentage affected plants is observed in experiments and in practice, likely more factors than nutrient application are involved.

‘Tubing’ is a malformation in the leaf development which occurs primarily in young Guzmania and Vriesea plants. Instead of arranging themselves into the typical tank rosette, the central leaves form an upright oriented tube-like structure, causing losses up to 10 %. Tubing occurs when insufficient trichome-mediated water uptake – not just the absence of liquid in the tank – is combined with unrestricted root-mediated water uptake. Restoring water uptake by the trichomes can reverse tubing, which is accelerated by application of surfactant in the tank to improve water percolation between the pressed-together leaf bases. At the cellular level, tubing seemed to be linked to partial shrinkage of the hydrenchyma cells. Shrinkage was most prevalent in the adaxial hydrenchyma. This might cause the leaves to curl up, become orientated upright and form a tube in a process similar to the leaf rolling other monocots, like maize (Zea mays L.), develop during drought stress.

 

Date:1 Oct 2013 →  30 Mar 2017
Keywords:Bromeliaceae, Water uptake, Nutrient uptake
Disciplines:Biochemistry and metabolism, Systems biology, Medical biochemistry and metabolism, Plant biology, Agricultural plant production, Horticultural production, General biology
Project type:PhD project