Boron behavior in apple plants in acidic and limed soil

Abstract

In dry Mediterranean-type climates boron (B) levels may naturally be high and even toxic to plants. Although liming of an acidic soil is expected to decrease B levels, it is not known what the effects would be in such areas of high-B soils, especially in B-sensitive crops such as apple trees. Thus, our aim was to study the behavior of added B in newly planted apple rootstocks in an acidic soil which was limed to pH 6.5 in an outdoor pot experiment. Added B increased significantly B extractability from soil, and B levels were lower in the limed compared to the acidic soils. Plant B concentrations also increased with added B but differences between limed and unlimed soils were not evident, because plant B did not seem to reflect changes in B behavior in soil. However, B uptake was significantly increased with added B, and was further increased with liming, contrary to what the soil extractions indicated, due to improved growth conditions. Our results show that although liming decreased soil B levels, at the same time it did not affect plant B concentration and accelerated the uptake of added B, indicating a possibility for increased soil-to-plant mobility of B.