Enhancing the Defensive Mechanism of Lead Affected Barley (Hordeum vulgare L.) Genotypes by Exogenously Applied Salicylic Acid

Lead is a non-essential element reduced plant growth and development that may cause multifarious disturbance in physiological, biochemical and structural integrity of plants. SA is an efficient signal molecule induces systemic resistance responses that control local defense reactions in plants. To evaluate the effect of SA on photosynthetic activity of Pb affected plants therefore a pot experiment was conducted on barley genotype Juo- 93 and Juo- 87 in the Old Botanical Garden, University Of Agriculture, Faisalabad, Pakistan. Three treatment levels (0, 100 and 200 µM) of lead sulphate (PbSO4) were applied in thrice replication with or without SA (0.5 mM) along half strength of Hoagland’s solution till the termination of experiment. The experiment was arranged in a completely randomized design. During course of study growth and pigments modulations were recorded. The result indicated that growth parameters such as root and shoot length, leaf area, fresh weight of shoot and root, dry weight of shoot and root were reduced under lead toxicity. Pb stress damaged the photosynthetic pigments such as Chlorophyll a, chlorophyll b, total chlorophyll and carotenoids but chlorophyll a/b was increased under Pb stress whereas exogenous application of SA alleviated the negative effect of lead toxicity. Juo- 93 showed more tolerance to Pb toxicity as compared to Juo-87.