Effect of salicylic acid on some plant growth parameters under lead stress in Brassica napus var. Okapi

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 its toxicity. The very important role of salicylic acid (SA) in response to different stresses, namely, modifications and decreasing the negative effects of stress has been established in different studies. The objective of this research was to evaluate the effect of different concentrations of salicylic acid to enhance the characteristics of Brassica napus L. under lead stress. Factorial experimental design was arranged in a completely randomized block design with three replications. Treatments were combination of 7 levels application of lead (0, 0.25, 0.5, 0.75, 1, 1.5 & 2 mM) and 2 concentrations of salicylic acid (5 & 10 ?M). The results revealed that increasing lead concentration reduced root and shoot length, leaf area, and root and shoot dry weight, root and shoot fresh weight, specific leaf area (SLA) and leaf weight ratio (LWR). Application of salicylic acid on the other hand, significantly increased the studied traits, although specific leaf weight (SLW) and leaf water content area (LWCA) were significantly increased with an increase in the concentration of Pb(NO3)2 (P < 0.01). Generally salicylic acid applications improved plant growth parameters of Brassica napus L.