Flowering response of Eremurus to post-harvest temperatures

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 degrees C, the second group to 20 degrees C followed by 2 degrees C, and the third group to 20 degrees C foll owed by 32 degrees C and, subsequently, 2 degrees C. Scanning electron micr oscopy (SEM) was used for concurrent morphological analysis of floral devel opment. Application of 2 degrees C to the plants in the initial stage of fl oral development caused plant destruction and death, while the same treatme nt applied at the stage of full differentiation promoted normal flowering. Temperatures of 20 degrees C and, especially, 32 degrees C, significantly i mproved flowering of the plants harvested in the early stages of florogenes is, whereas the same treatment applied to the plants harvested at the end o f flower differentiation did not affect the flowering process. A developmen tal disorder, which we term 'interrupted floral development' (IFD), was obs erved only in the plants harvested when the racemes were fully differentiat ed. This was probably caused by the very high air and soil temperatures tha t prevail in Israel during the summer. The extent of floral differentiation has a determinant role in subsequent scape elongation and flowering. (C) 1 999 Elsevier Science B.V. All rights reserved.