Flower senescence in Iris kashmiriana Baker

Some physiological changes accompanying iris flower (Iris kashmiriana) senescence were monitored. Flower development and senescence was catagorized into six stages, each separated by one day. Fresh and dry weight of flowers increased as they developed and opened (stages 1 to 4) and then declined with senescence (stages 5 and 6). Total soluble sugars and reducing sugars in the perianth tissue increased as the flower opening was completed and then declined, whereas concentration of tissue phenolics followed a declining trend with development and senescence. The soluble protein content decreased throughout flower development and senescence with a concomitant increase in free amino acids. Floral buds were detached from the plant at stage 2 and placed in distilled water (control), silverthiosulphate (0.5 mM) and cycloheximide (0.5 mM). Some buds were only given pulse treatment with these chemicals before placing them in distilled water. The life span of opened flowers on the plant and also of detached flowers in distilled water was two days. Silverthiosulphate had no effect on the senescence and longevity of flowers. Senescence probably was caused by selective degradation of certain proteins as cycloheximide treatment maintained a higher protein content in the perianth tissue of flowers and effectively delayed senescence and significantly enhanced the longevity of detached flowers to five days compared to two days in untreated flowers.