EFFECT OF FLUORIDE AND SALICYLIC ACID ON SEEDLING GROWTH AND BIOCHEMICAL PARAMETERS OF WATERMELON (CITRULLUS LANATUS)

The effect of sodium fluoride (NaF) on seed germination and biochemical parameters were studied in in vitro grown seedlings of watermelon (Citrullus lanatus) under salicylic acid (SA) treatment. After seven days of NaF treatment, reductions were observed in percentage of seed germination, root and shoot length, vigor index, pigment content, chlorophyll stability index (CSI), and membrane stability index (MSI) with increasing concentrations of NaF (1 and 10 mM). Seedlings treated with SA, both alone and in with combination of NaF, showed an increase in seed germination as well as other growth parameters. NaF-treated seedlings were found to accumulate more soluble sugars and phenolics, which were further increased by SA treatment thereby indicating a synergistic effect of SA and NaF on the accumulation of sugars and phenols. Therefore, these parameters are not directly related to a higher vigor index, membrane stability, and seedling growth. Treatment with SA reduced the adverse effects of NaF by increasing seed germination, root and shoot length, vigor index, pigment content, CSI, and MSI by some mechanism other than the accumulation of sugars and phenols. The possible reasons for the ameliorative effects of SA in seedlings of watermelon growing under F stress are discussed.