Abscisic Acid Content of Senescing Petals on Cut Rose Flowers As Affected by Sucrose and Water Stress

Abstract

Leafless cut Superstar roses (Rosa hyb.) were kept in a 1% sucrose solution. During the first few days of treatment, the abscisic acid content and the water deficit in the petals was higher in treated flowers than in controls kept in water. Later and up (3,7,10). Sucrose is the main transport form of the products of photosynthesis. When flowers are cut, they are severed from their sucrose supply and this no doubt is one of the reasons for imperfect development and the shorter life span of the cut flower (17). Sucrose supplied exogenously, promotes normal development of the cut flower, lengthens its life span, diminishes the change in petal color, and reduces proteolytic breakdown (1,3,16 flower stems were graded to a uniform length of 40 cm and before placing in 500-ml vases containing the treatment solutions, all leaves were removed from the stem. The flowers were kept under controlled conditions of 20 t 1 C, 55 t 10% relative humidity, and continuous illumination from cool white fluorescent light at a light energy flux density of 650 MAw/cm2. The base of the flower stalk was recut every other day and the solutions in the vases was brought up to a volume of 500 ml. The environment was not changed in experiments involving water stress, but flowers were removed from the solutions for specified periods of times (Fig. 3, Table I). At the end of the stress treatment the stems were recut. Some of the flowers which had been subjected to water stress conditions for 4 hr were given a recovery treatment. This consisted of wrapping the flower bud with wet blotting paper after the flower had been returned to its vase containing the treatment solution. This treatment raised the humidity around the flower to 90 to 100%. All treatment solutions contained 300 ,ug/ml A12(SO4)3 16 H20 to prevent development of bacteria.Extraction and Determination of ABA in Petals. Extraction, separation, and identification methods were adapted from those described in previous reports (10,15,18,19). Details of certain changes follow. Extraction and Purification. Each sample consisted of all the petals from five flowers. Samples were weighed (12 to 30 g fresh weight) and blended in 80% methanol (10 ml/g) for 2 min in a Waring Blendor. The resulting suspension was shaken for 18 hr at 4 C in the dark. After filtering, the solids were further extracted by shaking in the dark for 1 hr at 4 C with 3 ml/g 100% methanol. The combined methanol fractions were evaporated down to the aqueous phase at 38 C under vacuum. After centrifugation for 20 min at 500g, the supernatant was brought to pH 8.3 with NH40H and washed three times with methylene chloride (v/v) which was then discarded. After acidifying the aqueous phase to pH 3 with HCI, it was washed six times with methylene chloride (v/v), after which the aqueous phase was discarded. The methylene chloride fraction was evaporated to dryness at 38 C under vacuum.Preparative TLC. Samples were dissolved in 1 ml methylene chloride and these were loaded as a band on glass plates (20 x 20 cm) coated w...

New Plant Growth Regulators Protect Photosynthesis and Enhance Growth Under Drought of Jack Pine Seedlings

“…An increase in ethylene production was rapidly followed by an increase in tonoplast permeability in carnations (Mayak et al 1977). Permeability changes caused a massive loss of phospholipids in senescencing rose petals (Borochov et al 1976). This suggests that the loss of membrane integrity under drought could result from an effect of ethylene on phospholipids.…”

Physiology and Biochemistry of Flower Petal Senescence

“…Flower petals treated with ABA are more sensitive to exogenous ethylene (Ronen and Mayak 1981). Endogenous levels of ABA have been shown to increase in rose (Mayak and Halevy 1972;Borochov et al 1976b) and carnation petals (Nowak and Veen 1982;Eze et al 1986) during senescence. In carnations, the increase in petal ABA content was detectable prior to the loss of fresh weight and could be prevented by pretreatment with silver thiosulfate (Nowak and Veen 1982).…”

Flower bud opening and senescence in roses (Rosa hybrida L.)

“…These results indicate that ABA participates in the endogenous regulation of senescence processes in rose flower (Halvey and Mayak 1981). Borochov et al (1976) reported that ABA accelerates senescence of cut roses by promoting petal growth and respiration, thus decreasing carbohydrate concentration in the petals and triggering the chain of metabolic processes leading to ageing. During the vase life of a rose flower ABA concentration decline during the first 3 days, followed by a steady state at a low level, and finally a sharp increase in the late senescence (Page-Degivry et al 1991).…”