Analysis of spring barley intraspecific polymorphism in connection with tolerance to lead

Under technogenic pollution, phytotoxicity of heavy metals (HM) becomes a factor limiting yield and quality of crop production. In breeding, an intraspecific polymorphism of resistance to technogenic factors should be estimated with the analysis of its formation and maintenance. Using spring barley ( Hordeum vulgare L.) Zazerskii 85, Gorinskii and Chelyabinskii 1 varieties, we studied the influence of different Pb(NO 3) 2 concentrations (1,0; 1,5; 2,0; 2,5; 3,0; 3,5; 4,0; 4,5; 5,0 mg/ml) on the growth of roots and offsprings in seedlings. Then, a testing concentration of Pb(NO 3) 2 found out was applied to investigate an intraspecific polymorphism of barley plant tolerance to the toxicant. The cultivars from the VIR World Collection (N.I. Vavilov Research Institute of Plant Industry, St. Petersburg) were tested using seeds reproduced in 2008, 2009 and 2010 (36, 100 and 24 varieties, respectively). The varieties were divided into classes according to Sturgis’s rule. The lead sensitive and lead tolerant forms were separated basing on a depression coefficient. According to root growth, the highest tolerance was observed in the Gorinskii variety, and the Zazerskii 85 variety was the most sensitive. The influence of lead resulted in a shift of distribution of 100 cultivars to less offspring length, but according to Kolmogorov-Smirnov criterion there were no significant differences between the empiric distributions (D = 0.17 0.05 = 0.26). The tolerance to lead in varieties from the first and the last classes differed 2.0-4.5 times (i.e. from total suppression to growth stimulation). According to the length of the offsprings from the seeds reproduced in 2008 and 2010, there were no reliable differences from control (D = 0.167 0.05 = 0.434 and D = 0.125 0.05 = 0.531, respectively). A statistically unreliable stimulation of the seed germination also occurred (D = 0.306 0.05 = 0.320 and D = 0.208 0.05 = 0.392, respectively), probably because of less number of the tested samples. Lead caused multiple changes of the root morphology. Basing on morphological parameters, the varieties with a contrast tolerance to lead was revealed. Possible mechanisms of polymorphic tolerance of barley cultivars and other plants to HM are discussed. These data can be used under creation of agricultural plants tolerant to heavy metals.