The ‘tubing’ phenomenon in commercial cultivation of Guzmania: morphology, physiology and anatomy

•Tubing is a malformation in leaf development occurring in cultivation of bromeliads.•Instead of the typical bromeliad rosette leaves form a tubular structure.•Insufficient water uptake by the trichomes while roots take up water induces tubing.•Tubing is connected to shrinkage of adaxial hydrenchyma, similar to leaf rolling.•Tubing can be cured and prevented by application of surfactant to the tank solution.

Bromeliad breeders and growers in Belgium and the Netherlands report severe losses due to leaf ‘tubing’ in ornamental bromeliad production. This 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 tubelike structure. This detracts from the appearance of the leaves and makes it impossible to develop the central inflorescence that makes bromeliads attractive as an ornamental.Experiments showed that leaf tubing occurs when water is available to the roots but water uptake by the absorbing leaf trichomes is restricted. This situation was created by not supplying water to the tank and by lowering the water potential of the tank solution. Restoring water uptake by the trichomes could reverse tubing to some extent. Adding a surfactant to the water in the bromeliad tank helped in preventing tubing and accelerated the recovery of affected plants, likely by improving water percolation between the 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.