ASSESSING THE EFFECT OF FOLIAR AND SOIL FLUORIDE STRESS ON TURNIP (BRASSICA RAPA L.)

The production of crops in Pakistan is severely affected by the widely prevalent problem of salinity in the soil with salts including fluoride. The aim of the present study was to examine, in a pot experiment, the effects of sodium fluoride (NaF), applied as a foliar spray and as a soil drench, on the growth and other attributes of turnip (Brassica rapa L.). The percentage reduction in root length after treatment with a soil drench and a foliar spray was found to be at a maximum in plants treated with 300 ppm NaF, 62.6% and 51.02%, respectively, at 50 days after sowing (DAS) and 66.4% and 54.59%, respectively, at 70 DAS. The percentage reductions in the number of leaves, at 50 and 70 DAS, was 50.03% and 65.23%, respectively, for plants having an application of 300 ppm sodium fluoride by soil drench, while the corresponding reductions for the application of the 300 ppm NaF by foliar spray were 50.03% and 58.7%, respectively. At 50 DAS, the least percentage reduction in leaf area, 2.18%, occurred when the plants were given 50 ppm NaF by foliar spray and the highest value, 59.87%, was for the plants given 300 ppm NaF by soil drench. After 50 DAS, the percentage decrease in shoot fresh weight was found to be highest, 78.84%, when 300 ppm NaF was used as a soil drench, with the corresponding figure for the foliar spray application being 76.65%. Similarly, at 70 DAS, the percentage reduction in fresh shoot weight increased gradually with higher concentrations of NaF and was a maximum at 300 ppm NaF with both methods of application. We concluded that the application of NaF as a soil drench caused a greater reduction in the various parameters of turnip plant growth than did application as a foliar spray.