Effect of Growth-Regulators on Ripening, Split Peel, Reducing Sugars, and Diastatic Activity of Bananas

Abstract

1. Treatment of stems of bananas immersed in solutions containing 1000 p.p.m. sodium 2,4-dichlorophenoxyacetate (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), or para-chlorophenoxyacetic acid (CPA) resulted in an accelerated rate of ripening when compared with controls. Pulp ripening, as indicated by palatability and consistency, was accelerated somewhat more than skin ripening, as indicated by color index. These results were obtained when bananas were ripened in a well-ventilated improvised ripening room without temperature or humidity control. In an inclosed standard banana-ripening room at a controlled temperature, stems of bananas treated with 2,4-D ripened at the same rate as the controls. In the improvised ripening room bananas treated with 2,4-D ripened more evenly and exhibited better coloring than did controls, despite variation in temperature between 58⚬ and 100⚬ F. and in relative humidity between 24 and 100%. Accelerated rates of ripening also occurred when either the cut end of the fruit stem was immersed in a solution of 1000 p.p.m. of 2,4-D or the detached hands of bananas were entirely or partly immersed in the treatment solution for a few seconds. Attached single fingers of bananas injected with a similar solution of 2,4-D turned yellow, while adjacent fingers were still green. 2. Treatment with 2,4-D significantly reduced the number of bananas exhibiting longitudinal splitting of the peel in the improvised room and also in the standard room with controlled temperature where no other effect of 2,4-D treatment was observed. 3. Significantly lower weight losses occurred in stems of fruit treated with 2,4-D than in corresponding controls in the well-ventilated improvised ripening room, suggesting water retention by the tissues as a result of treatment. 4. Reducing-sugar content and diastatic activity of 2,4-D-treated bananas were considerably higher than in corresponding controls by the fourth day after treatment. The results indicated a marked increase in the rate of these processes as a result of 2,4-D treatment.