The soils of this ginseng growing area are slightly acidic (pH 5.4–5.5) and contain low organic buy Palbociclib matter, 1.5–2.1%, (Table 1) [8]. These soils are also low in B [9], with a normal concentration of 1.8 μg/g. Application of a high rate of B (8 kg/ha) raised the average B soil concentration available for the three ages of ginseng to 2.6 μg/g, (range 2.2–2.8 μg/g, Table 1); a 40% increase. Gupta and Arsenault [24] reported soil B levels of 3.0–3.4 μg/g where B had been applied at 8.8 kg/ha. There were no differences among the treatments in calcium and manganese (Table 1). Although there were some differences in phosphorus,

potassium, magnesium, and zinc, these were relatively minor and did not show a pattern. Smith and Clark [27] also reported no significant effect of excess B on the soil concentration of mineral elements other than B. The most striking aspect about the distribution of B in ginseng plants grown on soil supplemented with 8 kg/ha B was elevated concentrations in the leaves of each age of plant, compared to the treatment with 1.5 kg/ha B (Table 2). The B concentration this website in the leaves was increased by about 10–19-fold in response to the treatment, whereas the concentration in the root was decreased by about 40%, and that in the stem was unaffected.

From ginseng field survey work, Khwaja and Roy [4] considered >100 μg/g B in leaves as excessive. In another perennial plant, kiwifruit, Actinidia deliciosa var. deliciosa, Smith and Clark [27] reported that symptoms of B toxicity in leaves were associated with B levels in excess of 100 μg/g dry mass. Gupta and Arsenault [24] found that B toxicity symptoms in tobacco were associated with B levels of 113–119 μg/g.

Nable et al [13], in a review of B leaf analysis in relation to toxicity, noted that B concentrations >300 μg/g generally indicate the presence of B toxicity. There others was a good relationship (R2 = 0.38, p < 0.01) between B levels in the top 15 cm of soil and B levels in leaves of 2-, 3- and 4-yr-old ginseng ( Fig. 1). Also, plants growing in soil containing >1.8 μg/g B showed toxicity symptoms in the leaves that had B in excess of 200 μg/g ( Fig. 1). For each increase of 1 μg/g B in the soil, the leaf B increased by 236 μg/g ( Fig. 1). Smith and Clark [27], working with the woody perennial, kiwifruit, also growing in field soil, reported an increase of 117.5 μg/g B in the leaves for each increase of 1 μg/g B in the soil. Previously, Yermiyahu et al [25] irrigated grapevines growing in perlite in pots with four concentrations of B and found that B accumulated in leaves linearly, as found here for ginseng. The rate of B accumulation for the grapevines varied from 22.9 mmol/kg per mM in March to 515 mmol/kg per mM in September.