Date of Award
Master of Science
Plant, Soil and Environmental Sciences
Dennis E. Deyton
David L. Coffey, John R. Mount
Succinic acid 2,2-dimethylhydrazine daminozide was applied at 0, 750, 1000, 1500, and 2000 ppm to 'Redchief Red Delicious' apple trees in 1981; and in 1982 at 0, 1000, 1500, and 2000 ppm to 'NuRed Rome' apple trees. About two weeks before normal harvest, daminozide treated trees were sprayed with 0 to 300 ppm of 2-chloroethylphosphonic acid (ethephon) as an ethylene source and 10 ppm of sodium 1 naphthalene acetate (Fruitone N), a synthetic auxin. The fruit samples were evaluated to determine treatment effects on maturity and quality.
In 1981, fruits harvested at time of ethephon treatment and for six weeks thereafter revealed that ethephon applied to fruit previously treated with daminozide increased soluble solids and percent red color. Daminozide, alone, reduced endogenous ethylene formation, and increased fruit firmness. Soluble solids were reduced as a result of daminozide applied at 1000 ppm or greater; however, with an application of ethephon, soluble solids were equal to that of the control fruit.
In 1982, fruit samples were harvested at time of ethephon treatment and for five weeks thereafter. Ethephon applied on fruit from trees previously treated with daminozide increased soluble solids and red color development, as observed by the Hunter color difference meter "a," "a/b." and "tan-1 a/b" values. Ethephon de creased firmness and weight on these fruits previously treated with daminozide. All daminozide treatments increased fruit firmness. Soluble solids were reduced from an application of daminozide at 2000 ppm. In 1982, the ethephon application overcame the increased fruit firmness imparted by the 1000 and 1500 ppm daminozide treatments.
Warlick, Lauretta K., "Effects of daminozide and ethephon on maturity of Red Delicious and Rome apples in Tennessee. " Master's Thesis, University of Tennessee, 1983.