Bud necrosis, a storage disease of tulips. III. The influence of ethylene and mites

Abstract

Experiments demonstrated that bud necrosis in tulip bulbs is caused by mites that penetrate the flower bud during storage. This penetration is only possible if the buds, which are normally closed, are open at their tips. Such buds were found after administration of ethylene (3 ppm) during storage at 20~ shortly after lifting and in 'Red Champion' also after storage at higher temperatures (20 to 23 ~ in ethylene-free atmospheres. Open buds, caused by ethylene, resulted from unequal growth inhibition of the young leaves and stamens. The difference in sensitivity of both organs to ethylene decreased during storage. Later on, the growth inhibition of stamens and leaves became equal, and the buds remained closed. Then ethylene caused blasting of the flower buds. Open buds in 'Red Champion', caused by higher storage temperatures, resulted from aberrant differentiation of the tips of the young leaves.

Bud necrosis, a storage disease of tulips IV. The influence of ethylene concentration and storage temperature on bud development

“…The length of buds and stamens was measured and the degree of inhibition calculated. Bud deformation was estimated according to a scale from 0 to 6 (De Munk, 1972), scores of 3 and higher indicating that the buds are open and can be invaded by mites.…”

“…Bud deformation scores De Munk, 1972) tion increased with increasing ethylene concentrations. The degree of inhibition, however, is lower than that found for the leaves: inhibition was not complete at 100 ppm and very slight at 0.05 ppm.…”

“…In previous experiments (De Munk, 1972) tulip bulbs were exposed to ethylene at a concentration of 3 ppm and stored at 20~ The results raised questions concerning the influence of other ethylene concentrations and storage temperatures on the development and deformation of the buds.…”

“…The effect of ethylene on growth was studied only in bulbs exposed during the first ten weeks after lifting, because later exposure to ethylene causes flower-bud blasting (De Munk, 1972). The results concerning that disorder will be published separately (De Munk, in preparation).…”

“…This gas causes stronger inhibition of elongation growth of the young leaves of tulip buds than of the floral organs within these buds. As a consequence, the floral organs grow faster than the enveloping young leaves and the buds open, allowing mites to penetrate the bud and initiate decay starting at the stamens (De Munk, 1972).…”