Ailanthus Trees Research Articles

Root competition for phosphorus between ginger and Ailanthus triphysa in Kerala, India

To acquire information on the nature of belowground interactions in intercropping system involving ginger, Zingiber officinale Roscoe, and Ailanthus triphysa (Dennst.) Alston, their root activity was evaluated based on 32P recovery by each species in mixed and sole crop situations. Treatments included two Ailanthus densities (1,111 and 3,333 tress ha−1) and four lateral distances of 32P application (10 and 20 cm from the treated ginger plant and 20 and 40 cm from the treated Ailanthus trees). Recovery of 32P in ginger foliage increased with time, irrespective of tree population density and lateral distance of isotope application. Lack of significant variations in 32P recovery as a function of tree population density suggests that tree density is probably not a strong determinant of belowground competition in the well-fertilised, manured and mulched system studied (at least till four years after tree planting). Nonetheless, neighbouring Ailanthus trees absorbed a substantial potion of the 32P supplied to ginger. This, in turn, suggests that the effective root zones of ginger and Ailanthus may overlap. Data on 32P uptake of Ailanthus suggest that 41% to 59% of the root activity is concentrated within a zone of about 40-cm distance from the trunk. Neighbouring trees in the high density stands absorbed significantly more 32P than those in low density stands (P < 0.01 at 30 and 45 days after 32P application). Our observations also suggest that competition between the tree and the herbaceous crop for nutrients applied to the tree component is unlikely in the Ailanthus-ginger mixed species system studied. Therefore, from a crop management perspective, it is better to fertilise the herbaceous component of the mixed species system adequately, as it will also benefit the tree component. Nutrient use efficiency may be higher under such situations.