RESUMO
Boron (B) is toxic to most plant species when accumulated in high concentrations. Differences in a plant's ability to adapt to high concentrations of B may depend on the origin of the germplasm. Chilean and domestic (U.S.) germplasm, corn (Zea mays L.), carrots (Daucus carotas), tomato (Lycopersicum esculentum L.), and alfalfa (Medicago sativa L.) were evaluated for germination, emergence of cotyledonary leaves, and tissue B accumulation under high-B conditions in both an environmental growth chamber and a greenhouse. Increasing B levels (20-40 mg B liter-1) inhibited the percentage germination for both the Chilean and domestic germplasm. Chilean germplasm exhibited generally a greater percentage of healthy cotyledonary leaves at the 20 mg B liter-1 treatment than the domestic germplasm. Comparing B concentrations between both germplasm grown and irrigated with B-enriched water (10-20 mg B liter-1) under greenhouse conditions, leaves from domestic germplasm contained more B. Moreover, B troxicity symptoms were more severe for the tested plant species from the domestic germplasm. Apparent B tolerance by germplasm of different origin should be further tested under field conditions.