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Abstract

Availability of phosphorus (P) in soil and its acquisition by plants is affected by the release of high and low molecular weight root exudates. A study was carried out to ascertain the qualitative and quantitative differences in root exudation among the genotypes of maize (Zea mays L.) and green gram (Vigna radiata L.) under P-stress. Results showed that both inter- and intra-species differences do exist among maize and green gram in terms of root exudation, P uptake, and shoot and root P content. In general, green gram, a legume crop, had greater root exudation compared to maize. However, the amino acid content of the total root exudates in maize was two-fold as compared to green gram. The maize and green gram genotypes possessed genetic variability in root exudation.Irrespective of the species or genotypes, a positive relationship was found among P uptake rates, total root exudation, and shoot and root 32P content. The amount of sugars and amino acid present in the root exudates of P-starved seedlings also add to the variation in P uptake efficiency of genotypes.