Sarhad J. Agric. Vol.27, No.2, 2011 171 ROLE OF EXOGENOUS SALICYLIC ACID APPLICATIONS FOR SALT TOLERANCE IN VIOLET KHALID HUSSAIN*, KHALID NAWAZ*, ABDUL MAJEED*, UMBRIN ILYAS*, FENG LIN**, KAWSAR ALI*** and MUHAMMAD FARRUKH NISAR* * Department of Botany, University of Gujrat, Gujrat – Pakistan. ** Shenyang Agricultural University, China. *** Department of Agronomy, Khyber Pakhtunkhwa Agricultural University Peshawar – Pakistan. Email: kahlidbotany@Inbox.com ABSTRACT Role of exogenous applications of salicylic acid (SA) under NaCl stress in violet (Viola odorata L.) was investigated in soil filled earthen pots during 2009-10 at University of Gujrat, Pakistan. There were three treatments comprising control, 50-mol m -3 NaCl, and NaCl (50-mol m -3 ) + SA (30-mg l -1 ). NaCl significantly reduced the plant and root lengths, plant fresh and dry weights. In contrast, NaCl did not show any adverse effect on plants when supplemented SA. SA treated violet plants under NaCl salinity strongly reduced accumulations of Na + , K + , Ca 2+ and Cl − and glycine betaine and total soluble carbohydrates as compared to NaCl treatments. Higher N and relative water contents (RWC) was noted in T 2 (NaCl+SA) but it reduced in T 1 (NaCl) as compared to control. It was concluded that SA could be used as a potential growth regulator to improve salt tolerance in plants. Key Words: Exogenous, salicylic acid, growth, ion contents, salt tolerance, violet Citation: Hussain, K., K. Nawaz, A. Majeed, U. Ilyas, F. Lin, K. Ali and M.F. Nisar. 2011. Role of exogenous salicylic acid applications for salt tolerance in violet (Viola Odorata L.). Sarhad J. Agric. 27(2): 171-175 INTRODUCTION The violet (Viola odorata L.) is a low-growing perennial herb. Mainly it is propagated through seed and rootstocks. Based on traditional lore, the leaves and flowers of violet are regarded as antiseptic and expectorant (Kowalchik and Hylton, 1998). Violet leaves are also considered good remedy traditionally in bronchitious, mucus, coughs, asthma, cancer of breast, stomach, lungs and digestive tract (Bown, 1995). When plants are exposed to salt stress, they adapt their metabolism in order to cope with the changed environment. Survival under these stressful conditions depends on the plant’s ability to perceive the stimulus, generate and transmit signals and instigate biochemical changes that adjust the metabolism accordingly (Hasegawa et al. 2000). Salicylic acid (SA) plays an important role in the defense response to pathogen attack and stresses in plant species (Shakirova et al. 2003). Several studies also supported a major role of SA in modulating the plant response to several abiotic stresses including salt and water stress (Yalpani et al. 1994; Senaratna et al. 2000). Treating mustard seedlings with SA improved their thermotolerance and heat acclimation (Dat et al. 1998). In maize plants, pre-treatment with SA induced the production of antioxidant enzymes, which in turn increased chilling and salt tolerance (Janda et al. 1999). The objective of the present study was to assess the role of exogenous salicylic acid applications for salt tolerance in violet. MATERIALS AND METHODS Seeds of violet (Viola odorata L.) were obtained from Shakarganj Botanic Garden, Jhang-Pakistan. Seeds were surface sterilized by dipping in 10% sodium hypochlorite solution for 10 min, then rinsed with sterilized distilled water and air-dried at an ambient temperature of 32°C in the laboratory. Following treatments of NaCl salinity and SA were applied 21-days after germination. There was a total of 30-pots comprising 10- pots for each treatment. T 0 = Control (without any treatment) T 1 = NaCl 50-mol m –3 T 2 = NaCl 50-mol m –3 + SA (30-mg l -1 ) Salinity levels were developed as: 1 mole of NaCl = 58.5 g NaCl dissolved in 1 liter water 1 mol m -3 = 0.0585 g NaCl dissolved in 1 liter water 10 mol m -3 (1 dS/m) = 0.00585 g NaCl dissolved in 1 liter water 50 mol m -3 (5 dS/m) = 0.00583 X 50 g NaCl per pot=0.292 g/pot