Abstract
The objective of the present study was to assess the effects of sodium fluoride (NaF) on the growth and yield components of okra (Abelmoschus esculentus) in order to identify plant growth parameters that could be used for the early evaluation of different cultivars for fluoride stress. Two okra cultivars, Arka Anamika and Nirali, were studied in 80 pots and watered twice weekly, starting 31 days after sowing, with either tap water (control) or various concentrations of NaF (50, 100, 150, 200, 250, and 300 ppm). The plants were harvested 70 days after sowing. The yield parameters (no. of pods, pod length, fresh and dry pod weight, no. of seeds, fresh and dry weight of seeds) were found to decrease as the concentrations of sodium fluoride increased. The Nirali cultivar was more sensitive to fluoride stress than the Arka Anamika cultivar. In the Nirali cultivar, the no. of flowers decreased with an increase in the NaF concentration from 150 to 300 ppm. In the Arka Anamika cultivar, plants treated with 200 and 300 ppm NaF showed a reduction in the no. of flowers. There was a gradual reduction in the no. of pods as the NaF concentration increased in both cultivars. The percentage reductions in the pod length for the Nirali cultivar with 50, 100, 150, 200, 250, and 300 ppm NaF were 10.30, 17.09, 24.63, 30.24, 31.48, and 42.59%, respectively, as compared to the control. The effect of NaF on pod length in the Arka Anamika cultivar showed a similar trend to that found with the Nirali cultivar. The fresh and dry weights of the pods showed a maximum percentage reduction with 300 ppm NaF, (Nirali: 53.69% and 56.2%; Arka Anamika: 57.23% and 52.17%, respectively). For both cultivars, the no. of seeds per plant decreased with increasing NaF concentrations. In both cultivars, all these parameters were inversely related to the NaF concentrations with the reductions in the plant yield parameters being less in the 50 and 100 ppm NaF-treated plants than in the 250 and 300 ppm NaF-treated plants.