Flowering response of Eremurus to post-harvest temperatures

Abstract

The influence of post-harvest temperature on the flowering response of the ornamental geophyte Eremurus was studied. The plants were harvested at four different stages of development and were separated into three groups. The first group was immediately exposed to 2°C, the second group to 20°C followed by 2°C, and the third group to 20°C followed by 32°C and, subsequently, 2°C. Scanning electron microscopy (SEM) was used for concurrent morphological analysis of floral development. Application of 2°C to the plants in the initial stage of floral development caused plant destruction and death, while the same treatment applied at the stage of full differentiation promoted normal flowering. Temperatures of 20°C and, especially, 32°C, significantly improved flowering of the plants harvested in the early stages of florogenesis, whereas the same treatment applied to the plants harvested at the end of flower differentiation did not affect the flowering process. A developmental disorder, which we term `interrupted floral development' (IFD), was observed only in the plants harvested when the racemes were fully differentiated. This was probably caused by the very high air and soil temperatures that prevail in Israel during the summer. The extent of floral differentiation has a determinant role in subsequent scape elongation and flowering.