Hydraulic lift in mango trees (Mangifera indica L.) and early growth of intercropped groundnut (Arachis hypogaea L.).
Harigane I., Sakuratani T., Higuchi H., Nawata E., Asano S., Yamamoto S., Maskow I.
Author Affiliation: KOSE Corporation, Tokyo 103-0027, Japan.
Tropical Agriculture and Development 53 : 90-94
Abstract : A split-root experiment conducted under greenhouse conditions by Hirota et al. showed that water transferred to the surface roots of a tree (Markhamia lutea) from deeper roots was released into the soil, and that upland rice plants planted near the tree remained viable, while those planted alone became desiccated. This paper presents the results of a study, planned on the basis of that of Hirota et al. (2004), to examine the influence of hydraulic lift (HL) on crop growth under natural conditions. To focus on the effects of HL, 2 plots with similar solar radiation were established: one plot in which the lateral roots of the tree were removed so that competition for water do not occur between the tree and the crop, and another plot in which the lateral roots were not removed. The study was performed in a mango field in Northeast Thailand during the dry season in November-December 2004. Mango trees were chosen because they have both deep and shallow roots. Groundnut was used as a test crop because they exhibit a strong resistance to soil dryness and is low-growing. It was assumed that such crops could survive for a long time under drought conditions with the small amount of water supplied by HL. The photosynthetic photon flux density of groundnut, soil volumetric water content, sap flow in mango roots, and leaf water potential in groundnut were determined. The results confirm the possibility that water supply from HL may improve the water status of small crops associated with competition for water between trees and crops.