Abstract
In this study, an examination was made of the size, fresh weight, and dry weight of turnip, Brassica rapa L., at 70 days after sowing (DAS) when different concentrations of sodium fluoride (NaF) (0 [control], 50 [NaF-50], 100, 150, 200, and 300 [NaF-300] ppm) were applied. The size of the turnip was maximal in the control plants, 20.82 cm(2). In the plants given NaF-50, as both a soil drench and as a foliar spray, the sizes were 16.32 cm(2) and 18.08 cm(2), respectively. The size of the turnip gradually decreased as the NaF stress was increased and was at a minimum with NaF-300 for both methods of application (soil drench: 2.47 cm(2), foliar spray 4.35 cm(2)). At 70 DAS, the fresh weight was greatest, 66.60 g, in the control plants, followed by 43.06 g, in the plants given NaF-50 by foliar spray. The fresh weight successively declined as the concentration of NaF increased and at NaF-300 and it reached a minimum for both the soil drench, 1.36 g, and the foliar spray, 2.43 g. The dry weight was recorded by oven drying the fresh turnip at 70 DAS, and found to be at a maximum in the control plants, 6.60 g. When a fluoride stress was applied with NaF-50, as a soil drench and a foliar spray, the dry weight decreased to 4.30 g and 5.06 g, respectively. As the concentration of NaF increased, the dry weights decreased in a manner similar to that found with the fresh weights and the lowest values were found with NaF-300 (soil drench: 0.556 g, foliar spray: 1.20 g). In conclusion, NaF applied as both a soil drench and a foliar spray, at concentrations of 50-300 ppm, reduced the size, fresh weight, and dry weight of turnip compared to a control group with 0 ppm NaF. The application of the NaF by soil drench caused a greater degree of stress to the turnip than did the application by foliar spray.