EFFECTS OF APPLIED AND RESIDUAL BORON ON THE NUTRITION OF CABBAGE AND FIELD BEANS

Abstract

Field experiments were conducted at four locations in Prince Edward Island to determine the effect of applied B on leaf tissue B and yields of beans (Phaseolus vulgaris L.) and cabbage (Brassica oleracea var. capitata L.) in the year of application of B and again the following year. Application rates of 8.8 kg B∙ha −1 reduced bean seed yields at all locations and the 4.4-kg B∙ha −1 rate reduced yields at two locations in the first year. Leaf tissue B levels > 109 μg∙g −1 are clearly toxic for beans and seriously reduced bean yields. Furthermore, the yield and visual symptom data strongly suggest that tissue B levels even as low as 60 μg∙g −1 are toxic for this crop. No significant reductions in bean yields were noted in the second year crop, even at the 8.8 kg B∙ha −1 rate. Rates of up to 8.8 kg B∙ha −1 did not cause any reduction in cabbage yield even during the year of application. Leaf tissue B concentrations as high as 71–132 μg∙g −1 were not related to any B toxicity in cabbge. Added B did not increase yield of either beans or cabbage. Even though leaf tissue B levels as low as 16 μg∙g −1 in cabbage and 26 μg∙g −1 in beans occurred, no B deficiency was found. After the first and second years of beans the hot-water-soluble B in the soil ranged from 1.4 to 1.9 and from 0.8 to 1.2 μg∙g −1 , respectively, where B had been applied at 8.8 kg∙ha −1 . Key words: Cabbage, beans, boron toxicity, tissue boron, yields