abstract the goal of this experiment was to save apricot flowers from late spring frost damage. this experiment was conducted during 2007-2008 to examine the effect of application of different concentrations of gibberellic acid in two forms pure (ga3) and impure (berelex) at (0, 50, 100, 200, 300 mgl-1) at 23 august and 23 september to delay flowering in apricot asgarabad cultivar. a factorial ...

Gibberellic acid, a tetracyclic dihydroxylactonic acid, C1H2206, produces marked shoot elongation in many plants (2, 3, 11, 12, 13). Unlike other auxins, its stimulation of growth of intact plants often results in substantial increases in height, and in fresh and dry weights (2). Brian (2) noted that the ash, nitrogen, phosphorus, potassium, total soluble carbohydrates, and carbon increased in ...

photosynthesis (1). Total radioactivity fixed per leaf was unchanged by the two-hour treatment with gibberellic acid; typical results are shown in table I. Similar results were also obtained in one experiment with Chlorella pyrenoidosa. Examination of autoradiograms of the chromatograms of extracts from the oats, barley, and peas showed no significant differences in the distribution of C'4 amon...

A bstract. Kinetin in concentrations of 10-e to 10-4 M, stimuated ethylene production in 3 and 4-day old etiolated seedlings of Alaska pea (Pisucm sativum L. var. Ala-ka). Seedlings of other species responded similarly. The response to kinetin depended on the age of the seedlings. Kinetin alone did not influence ethylene production in 6-day old stem sections, but it greatly increased the enhanc...

The development of xylanase activity by isolated barley (Hordeum vulgare cv. Himalaya) aleurone layers exposed to gibberellic acid was enhanced by ethylene, whereas the rate of glucanase synthesis was unaffected by ethylene. The elevated xylanase activity expressed in ethylene-treated tissue may be responsible for enhanced release of amylase in response to ethylene.The redistribution of ionic s...

An immunological assay has been used to investigate the synthesis of (1-->3,1-->4)-beta-glucanase (EC 3.2.1.73) isoenzymes from isolated barley aleurone layers and scutella. Enzyme release from both tissues is enhanced by 1 micromolar gibberellic acid and 10 millimolar Ca(2+), although increases induced by gibberellic acid are observed only in the presence of Ca(2+). Isoenzyme I is synthesized ...

Aging in leaves is characterized by a decrease in chlorophyll content and an accompanying loss of protein and ribonucleic acid. It is well known that these symptoms of senescence occur at an accelerated rate in excised mature leaves and in leaf discs floated on water. In recent years it has been established that several chemical substances retard the senescence of leaves. Among the compounds wh...

Because the endosperm half of a barley seed produces several hydrolytic enzymes in response to added gibberellins (1, 4, 5, 8), it is an attractive experimental system for a study of the mechanism of action of gibberellic acid. The only living cells in the half seed are those of the aleurone layers. These are an apparently homogeneous collection of respiring, nondividing cells which have the hi...

Histones from the epicotyls of light-grown dwarf peas (Pisum sativum L. cv. Little Marvel) which had been treated with gibberellic acid were compared to histones from control dwarf peas by the method of polyacrylamide gel electrophoresis. The histone complements were found to be unaltered in the electrophoretic mobility and relative quantity of the individual fractions. The ratio of histone to ...