Effects of naphthalene acetic acid on aborted okra production, antioxidants,minerals, phenol, flavonoid, and carotenoid content applied to flower ovary stigma

The experiment was carried out to investigate the effect of different concentrations of NAA (naphthalene acetic acid) on the seedless (aborted) okra production, vitamin C, carotenoids, flavonoids, antioxidants (DPPH), phenolic, and mineral content. The micro-syringe injection in flower stigma was an innovative application method used in this experiment, rather than spray, which was a common and traditional method. The flower stigma injection method was applied on the flower stigma after the anthesis of the flower of the okra plant using NAA at different concentrations. In Experiment 1: The lowest concentration (25 mg/l) of NAA greatly increased the pod setting compared to the higher concentrations and control. NAA application at 25 and 50 mg/l concentrations induced higher values of pod length, diameter, size, weight, ascorbic acid, and soluble solid content over the control. The chlorophyll content in leaves was affected significantly by different concentrations of NAA. It was found that 25 and 50 mg/l concentrations of NAA significantly increased chlorophyll content, fiber, moisture, flavonoid, carotenoid, antioxidant (DPPH), minerals, and phenolic content compared to the other concentrations and control. In addition to that, control and 25 mg/l concentrations of NAA increased the production of healthy seeds compared to the 50 and 100 mg/l. Moreover, 50 and 100mg/l of concentrations showed higher aborted seed (seedless) than the other concentration and control. In Experiment 2: In the second year, the residual effects of aborted seed (seedless) were found to have a decreasing trend of most of the parameters like pod weight, size, aborted okra percent, leaf chlorophyll, antioxidant (DPPH), and Vitamin C. But, NAA concentrations showed better residual effects in the second year in comparison to the control. Therefore, it seemed that 25 mg/l was the best concentration for pod growth and development, and 100 mg/l was the best for seedless okra production in the first and second years.