Effect of Solution Phosphorus Concentration on the Exudation of Oxalate Ions by Wheat (Triticum aestivum L.)

Phosphorus is one of the essential nutrients for plant growth and crop production. The importance of phosphorus in maintaining soil fertility and improving crop productivity has now been recognized much more than before in view of the fact that about 66 % of Indian soils are known to give universal response to P application and remaining 34 % to heavy feeding crops [ 1 ]. Phosphorus deficiency is a limiting factor of crop production in agricultural soils worldwide [ 2 – 4 ]. Correcting P deficiency with application of P fertilizers is not possible for the resource-poor farmers in the tropics and subtropics, especially on soil with high P fixing capacity. Knowledge about the principle mechanisms involved in efficient P acquisition by plants increased substantially during recent years [ 5 , 6 ]. It has been attempted to use organic acids like citric acid and oxalic acid to extract labile P as an indicator of soil P availability [ 7 , 8 ]. Low-molecular-weight oxalic acid plays an important role in the mobilization of soil phosphorus [ 9 ]. Oxalic acid exudation from roots is considered to be one of the mechanisms for plants to adapt to P deficiency [ 10 ] by mobilizing P in soil. The objective of the present study was to investigate the effect of solution phosphorus on the exudation of oxalic acid, in different varieties of wheat at different time intervals in sand culture.