Phosphorus Utilization Efficiency in Populations of Narrow-Leaf Birdsfoot Trefoil

Abstract

The widespread distribution of the pasture legume Lotus glaber Mill. throughout the Flooding Pampa in Argentina may be attributed to ecotypic differentiation among populations. In order to confirm such genetic variation, two morphologically distinct populations from contrasting soil types, particularly in the phosphorus (P) status, were compared in their response to a different P supply. Plants were cloned by stem cuttings and transplanted to a common soil fertilized with increasing amounts of P. Morphological characters including number of shoots, leaf length and width, as well as the leaf length/width ratio, remained different in spite of P supply. Biomass P content, tissue P concentration and the percentage of root length infected by mycorrhizae associated with P uptake, were similar between populations. However, both populations showed a different growth response to P fertilization in spite of being cultivated on the same soil. Consequently, they differed in the efficiency of P utilization (E), which is probably under genetic control. These results produce evidence in support of the existence of ecotypes for L. glaber adapted to local soil conditions.

Acknowledgments

This research was supported by the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) from Argentina. We want to thank Ing. A. Calvelo from Estancia Las Gramíneas (San Vicente) and the owner from the grassland in Verónica. We also appreciate the valuable comments on the manuscript from Dr. A.J. Barneix and the assistance of Mr. C.A. Hernández.