Tolerance of some wheat varieties to boron toxicity

Boron (B) toxicity is an important problem in low rainfall and highly alkaline soils of central and southern part of Iran. We evaluated B toxicity tolerance of 10 Iranian wheat varieties in a greenhouse experiment. Experimental design was factorial Completely Randomized Design (CRD) with 10 wheat varieties × six B levels (0, 2.5, 5, 10, 20 and 40 mg B kg ⁻¹ soil) in three replications. The results showed a great range of tolerance among wheat varieties. Arg was the most tolerant one and Chamran showed the least tolerance. It seems that different mechanisms involved in B toxicity tolerance, namely exclusion of B from root, redistribution of B within leaves and integration of these two mechanisms. Significant negative linear correlation observed between shoot B concentration and shoot dry weight (r = 0.85, p < 0.01) and positive linear correlation between shoot B concentration and shoot dry weight reduction percentage (r = 0.82, p < 0.01).