This study was aimed to assess the effects of excess boron on 59 genetically divergent wheat accessions and to identify those with high and stable yields under a range of soil boron concentrations. The second aim was to test the applicability of a laboratory technique performed at juvenile stages of development in estimating field boron tolerance. The study comprised a control and three boron treatments, applied as 50, 100 and 150 mg boric acid L-1 in laboratory, and 33.0, 67.0 and 133.0 kg

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... c acid ha-1 in field trial. Yield performance and stability were evaluated using biplots from sites regression model, while interrelationships among analyzed parameters were assessed using path coefficient analysis. Parameters were mostly decreased by excess boron when compared to the control (seedling root length, seedling dry weight, grain number per spike, grain yield, flag leaf area, leaf area duration and grain weight). Significant increase was noted for seedling boron concentration and content, percentage of sterile spikelets per spike and number of spikes per m 2. Spike length, number of spikelets per spike, and anthesis date remained unaffected. The majority of accessions with high and stable yields were of local origin, so, we conclude that adaptation to environmental factors other than elevated soil boron plays an important role in overall field boron tolerance. The effects of excessive external boron on boron accumulation noted at the seedling stage in laboratory studies corresponded to its effects on yield in field.