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Rhizobia1 Inoculation and Phosphorus and Zinc Nutrition for Annual Medics Adapted to Mediterranean Environments

Author:
Materon, Luis A., Ryan, John
Source:
Agronomy journal 1995 v.87 no.4 pp. 692-698
ISSN:
0002-1962
Subject:
Medicago, Medicago polymorpha, Mediterranean climate, Sinorhizobium meliloti, seed inoculation, nitrogen fixation, phosphorus fertilizers, zinc fertilizers, dry matter accumulation, nodulation, roots, crop yield, pods, cold tolerance, Medicago rigidula, species differences
Abstract:
Cereal production in the Mediterranean region (where rainfall averages 200 to 600 mm yr) has traditionally used fallowing in alternate years to conserve croplimiting soil moisture. Self-regenerating pasture medics (Medicago spp.) were introduced to provide forage for livestock in the alternate year and to reduce the cereal's need for fertilizer N; their adaptation depends on compatible bacteria for N fixation and on climatic conditions. In addition, nutrients such as P and Zn are potentially limiting factors. Therefore, in a greenhouse experiment (60 d) using a P-deficient, air-dried, nonsterilized clay soil (Calcixerollic Xerochrept) treated with P (0, E, 45, and US mg kg) and Zn (0 and 5 mg kg, we assessed growth of four annual medic species with and without rhizobial inoculation and fertilizer N: L., Boiss., (L.) All., and Boiss. Except for M. noeana, growth of all species responded significantly to applied P and to Zn only with adequate P and N levels (or rhizobial inoculation). Pod number and root biomass were also increased by P application, with differences occurring between species. Thus, when a medic species is newly introduced, inoculation has a role to play where no compatible rhizobia exist. Phosphorus fertilization and medic seed inoculation can easily be done, while the use of adapted biotypes in low-Zn soils is more problematic
Agid:
1463178