Effect of Growth-Regulating Substances on the Water-Retaining Capacity of Bean Plants

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Abstract
4-Chloro-phenoxyacetic acid (4-C1) was applied as a spray or a dip treatment to attached snap bean fruits 4 days before the usual harvest date. Effects on their subsequent development and on certain after-harvest changes in the fruits were studied. 1000 ppm. of 4-C1 retarded maturation of attached fruits. Fresh wt. of the treated fruits was 11.2, 10.1, and 11.4% greater than that of untreated ones when harvested 1,2, and 3 weeks after treatment. The 1st, 2d and 3d weeks after treatment, treated fruits contained 2.3, 8.7, and 14% more moisture, respectively, than did untreated ones harvested at comparable intervals. Appln. of the acid brought about a decrease of 22% in final dry weight of seeds produced, but the dry wt. of pods of treated fruits was 14% heavier than that of untreated fruits at maturity. Spray appln. of 4-C1 to attached fruit at concns. ranging from 250 to 1000 ppm. reduced the final yield of fresh fruit, the most concd, spray by 44%. A 50 ppm. spray did not reduce yield significantly under conditions used. Spray applns. of 4-C1 to attached fruits increased the water-retaining capacity of the fruits when they were harvested and stored. The acid retarded the rate of color change in harvested and stored fruits. These effects resulted from spray concns. ranging between 50 and 1000 ppm. Appln. of 4-C1 (400 ppm. spray) in a wax emulsion to the attached fruits was more effective in retarding evaporation of moisture from the fruits following harvest that was an equal concn. of the acid in a water spray. During the 1st week of storage, fruits sprayed with the wax-growth regulator mixture lost approx. 25% less moisture than the checks. Further investigations are necessary before appln. 4-C1 can be considered as a practical means of improving the storage quality of snap beans.