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Abstract

Papaya seedlings (cv.'Sunrise') were produced under greenhouse conditions to determine the effects of combinations of varying ethanol and gibberellic acid-3 (GA3) concentrations on papaya shoot height, leaf number, leaf area, and shoot dry weight. Seedlings were grown in 0.5-L plastic containers filled with a potting medium composed of 50% vermiculite, 30% periite, and 20% spaghnum peat (v/v). When seedlings were 10 cm tall and had two-true leaves, foliar sprays of ethanol (0, 5, 10, 15 or 20% v/v) and G A3 (0, 10, 20 and 30 ppm w/v) combinations were applied using a 5-mL solution volume. Treatments were arranged in a randomized complete block design with seven replications. Ethanol and GA3 concentrations interactively influenced plant height (P<0.05). In all cases, as GA3 rate increased there was an increase in plant height, regardless of the ethanol concentration utilized. Although, plant height increased when the 5% ethanol rate used (+13.7% for 0 GA3 treatments), higher alcohol concentrations caused a rapid decline in height. Treatments had no effect (P>0.05) on leaf number, whereas only ethanol rates affected papaya leaf area, with maximum area obtained with 5% ethanol (+32.6%). No significant ethanol by GA3 interactions (P>0.05) were observed for shoot dry weight. However, both factors individually influenced shoot dry weight. Leaf area, plant height, and seedling dry weight was higher when plants were treated with solutions containing 5% ethanol than when other rates were used, yielding 42.6% higher shoot dry weight than the untreated control. In fact, plants receiving rates of 10% ethanol or higher had a dry matter loss of at least 30% compared to untreated seedlings.

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