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ARS Home » Pacific West Area » Wenatchee, Washington » Physiology and Pathology of Tree Fruits Research » Research » Publications at this Location » Publication #181511
Title: THE INFLUENCE OF AMINOETHOXYVINYLGLYCINE AND ETHEPHON ON THE OBJECTIVE AND SENSORY QUALITY OF 'DELICIOUS' APPLES AND APPLE JUICE AT HARVEST AND AFTER STORAGE

Author
item Drake, Stephen
item EISELE, T - TREE TOP, SELAH, WA
item DRAKE, M - NC STATE UNIV., RALEIGH
item ELFVING, D - WSU, WENATCHEE, WA
item DRAKE, S - NC STATE UNIV., RALEIGH
item VISSER, D - WSU, WENATCHEE, WA

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2005
Publication Date: 11/1/2005
Citation: Drake, S.R., Eisele, T.A., Drake, M.A., Elfving, D.C., Drake, S.L., Visser, D.B. 2005. The influence of aminoethoxyvinylglycine and ethephon on the objective and sensory quality of 'Delicious' apples and apple juice at harvest and after storage. Hortscience. 40:2102-2108.

Interpretive Summary: Biogregulators can influence many important physiological processes in tree fruits when applied before harvest. Two bioregulators, aminoethoxyvinylglycine and ethephon have been widely used alone or in combination to manipulate both tree and fruit physiological behavior. Control of vegetative growth and regulation of flowering, preharvest drop, fruit maturity, fruit size, shape, color, firmness and postharvest quality have all been manipulated with the use of bioregulators. While many reports document effects on fruit quality, little information on bioregulator effects on sensory perception of fruit quality by consumers is available. A study by the Washington Apple Commission suggests that the key factor that stimulates sales of apples is flavor. Two important (aminoethoxyvinylglycine and ethephon) commercially available bioregulator products can affect fruit quality when applied to cropping trees before harvest. Could the ethylene biosynthesis-inhibiting properties of aminoethoxyvinylglycine be exploited to employ brief bursts of ethylene from pre-harvest exogenous applications of ethephon to temporarily stimulate ripening processes in apples without inducing the uncontrolled biosynthesis of ethylene in apple fruit and the accompanying loss of storability and quality? This study was conducted over three crop seasons using 'Scarletspur Delicious' apple trees on MM.111 rootstocks. Bioregulators, aminoethoxyvinylglycine (AVG) and ethephon (ETH) were applied alone or in combinations at various time intervals before harvest. Fruit response to bioregulators was evaluated at harvest and after storage. Use of AVG retarded starch loss at harvest, enhanced firmness, and reduced ethylene and watercore, at harvest and after both regular and controlled atmosphere storage. AVG did not influence peel color (hue values), but the flesh color of apples was greener when treated with AVG. Use of AVG reduced the sensory scores for apples and apple juice. Use of ETH, enhanced starch hydrolysis, flesh color development (green to more yellow), soluble solids and reduced titratable acidity levels. Ethephon had no influence on fruit firmness at harvest, but use of ETH reduced firmness levels after storage and this loss was related to the amount used. Sensory values for apples were not influenced by the use of ETH, but improved sensory preference for apple juice, particularly at early harvest. A combnation of AVG plus ETH, enhanced soluble solids and sensory scores for both fruit and juice. Firmness values were acceptable (>53.4N) after long-term storage, for fruit treated with a combination of AVG and ETH if the level of ethephon used was @ 150 ppm. Use of bioregulators alone (AVG and ETH) strongly influenced selected fruit quality characteristics, but there were quality disadvantages when used alone. Fruit quality was best at harvest and after storage with a combination of both AVG and ETH.

Technical Abstract: This study was conducted over three crop seasons using 'Scarletspur Delicious' apple trees on MM.111 rootstocks. Bioregulators, aminoethoxyvinylglycine (AVG) and ethephon (ETH) were applied alone or in combinations at various time intervals before harvest. Fruit response to bioregulators was evaluated at harvest and after storage. AVG applied 4 weeks before first harvest retarded starch loss at harvest, retained greater firmness, and reduced ethylene and watercore at harvest and after both regular and controlled atmosphere storage. AVG did not influence peel color (hue values), but the flesh color of apples was more green. Use of AVG reduced the sensory scores for apples and apple juice. In contrast, ETH enhanced starch hydrolysis, flesh color development (green to more yellow), soluble solids while reducing titratable acidity levels. Ethephon had no influence on fruit firmness at harvest, but reduced firmness levels after storage in an inverse relation to the concentration applied. Sensory values for apples were not influenced by the use of ETH, but improved sensory preference for apple juice, particularly at early harvest. Applying AVG prior to ETH enhanced soluble solids and sensory scores for both fruit and juice. Treating with AVG followed by ETH at 150 mg.1**-1 permitted the maintenance of satisfactory firmness values (>53.4N) after long-term storage along with enhanced quality and sensory perceptions. Using specific combinations of both AVG and ETH permitted the ETH-mediated improvements in objective and perceived fruit quality to be obtained without the losses in flesh firmness and storability due to uncontrolled ethylene evolution and ripening typically observed when ETH is applied alone preharvest.