Seedlings of Pinus patula were sprayed with salicylic acid (SA) at concentrations between 104 and 10(-10) M. At the end of the treatment root and shoots were harvested and nitrate and protein content determined. All the salicylic acid treatments increased significantly nitrate concentration in the roots; the 10(-10) and 10(-8) M treatments increased the amount of proteins in the roots, but in the shoots no significant effect was detected.