Study of Salicylic Acid Influence on Seedling Growth and Nitrogen Metabolism in Watermelon (Citrullus lanatus L.)

Abstract

Salicylic acid is involved in the regulation of metabolic activity and defense mechanism in plants under various stress conditions. Present study was conducted to determine the effects of salicylic acid (10 to 500 μM) on seedling growth, development and nitrogen use efficiency in watermelon (Citrullus lanatus L.) plants with or without nitrogen nutrient. Salicylic acid increased contents of chlorophyll, total non-structural carbohydrate and total nitrogen, as well as nitrate assimilation through the induction of nitrate reductase (EC 1.6.6.1) activity in isolated watermelon cotyledons. Accumulation of salicylic acid was two-fold higher in cotyledons without nitrate supply in comparison to that with nitrate supply. Further 50 μM of SA induced enhancement in seed germination and growth characteristics. However higher salicylic acid concentrations inhibited above physiological characteristics. Results show that, field application of salicylic acid need optimum physiological concentration (e.g., 50 μM) to increase nitrogen use efficiency particularly during germination and seedling growth.