Ecology, Environment and Conservation Paper

THE ROLE OF SALICYLIC ACID TREATMENT ON THE GROWTH, PHOTOSYNTHETIC PIGMENT OF BRASSICA NAPUS L. UNDER LEAD STRESS

Sheida Boroumand Jazi and Khosro Esteki Oregani

Abstract

The heavy metals pollution is a big problem for the large parts of the world. Lead is a heavy metal with high toxicity that Inhibition of germination and retardation of plant growth are commonly observed due to it toxicity. The very important role of salicylic acid (SA) in response to different stress and modification and decline damages due to stress has established in different studies. The objective of this research was to evaluate the effect of different concentration of salicylic acid on enhancement characteristics of Brassica napus L. under lead stress. The lead poisons and also the role of salicylic acid as a modifier on some of the physiological parameters in Colza (Opera and Okapi cultivars) were investigated. Then Colza seedlings were grown for 10 days in hydroponic culture in presence of Pb (NO3)2 (0, 0.25, 0.5, 0.75, 1, 1.5 and 2 mM). For observation of interaction effects of lead and salicylic acid, 3 levels of SA (0, 5 and 10 μM) with three replications were applied. The results indicated that the increase of lead concentration caused a significant reduction (p<0.01) in root and stem length, shoot and root dry weights and leaf area. Also photosynthetic pigments significantly decreased (p<0.01). The extent of toxicity increased with the increasing concentration of lead. Seedlings treated with both lead and salicylic acid showed an increase in most of the parameters compared to plants without salicylic acid treatment. In two colza cultivars, the application of exogenous salicylic acid counteracted the deleterious effects of lead on most of the parameters.