PARTHENOCARPY IN THE CUCUMBER INDUCED BY SOME PLANT GROWTH-REGULATING CHEMICALS

Abstract

Nine growth-regulating chemicals were sprayed at concentrations of 50 and 100 ppm on pickling cucumbers (Cucumis sativus L., cult Pioneer) in an effort to induce parthenocarpic fruit development. A morphactin formulation, IT 3456 (methyl-2-chloro-9-hydroxyfluorene-(9)-carboxylate), and TIBA (2,3,5-triiodobenzoic acid) were the most effective in stimulating parthenocarpic fruit-set and development at both concentrations used. Between six and seven fruits per plant were induced parthenocarpically when 100 ppm IT 3456 morphactin was used. Two other morphactins tested, IT 3233 (n-butyl-9-hydroxyfluorene-(9)-carboxylate) and Bay 102614 (2,7-dichloro-9-hydroxyfluorene-carboxylate-(9)-methyl ester), produced no more fruits than the control. A new growth regulator, CCDP (3-carboxy-1-(p-chlorophenyl)-4,6-dimethyl-2-pridone), significantly increased the number of fruits per plant at the 100-ppm concentration, and also increased the number of female flowers per plant produced within 50 days of planting, at both concentrations. The other four compounds tested, designated EL 531 (α-cycloprophyl-α-(4-methoxyphenyl)-5-pyrimidine methanol), BAS 0660-W (N-dimethyl-morpholiniumchloride), TD 692 (mono-("coco" dimethylamine) succinate), and Chemagro 8728 (5-chloro-2-thenyl-tributylphosphonium), were not effective inducers of parthenocarpy in the cucumber.