International Journal of Horticulture, 2017, Vol.7, No. 31, 288-298
293
Figure 1 Relationship of soil organic carbon content with nutrient absorption index
3.2 Effect of soil pH
Soil pH influenced negatively the absorption of P and S on own root; and Ca and S on Dog Ridge but none of the
nutrients on 110R (Table 2). Phosphorus absorption reduced with increasing levels of pH on own and Dog Ridge
roots respectively up to 8.13 and 8.19 (Table 2) and increased thereafter. Own root was more sensitive to soil pH
in the absorption of P compared to other roots. Though P absorption increased with pH up to 7.58 on 110R, the
response was poor. Efficiency of P absorption was highest on own root (Figure 2). The pattern of P absorption in
relation to pH on own root and Dog Ridge was in accordance with the P availability that was maximum at near
neutrality (soil pH 6.5–7.5), and decreased at higher and lower pH (Truog, 1946; Sumner and Farina, 1986).
Figure 2 Relationship of soil pH with nutrient absorption index
Soil pH also influenced calcium absorption significantly on Dog Ridge, but not on other roots (Table 2). Calcium
absorption was reduced with increasing levels of pH up to 7.51 on Dog Ridge, 7.88 on own root and 7.23 on 110R
(Table 3). Own root were more sensitive to soil pH than other roots. Rootstocks were more efficient in the
absorption of Ca at neutral pH. Higher pH levels (above 8) were favourable for Ca absorption (Figure 2). This
could be attributed to alkalinity (pH 7.76 ± 0.48) coupled with high free calcium content (16.2 ± 4.2) of the
