Effect of Different Fertilizing Systems on Seed Yield and Phosphorus Uptake in Annual Medics under Dryland Farming Conditions

Abstract

The effect of different fertilizing systems on the seed yield and phosphorus uptake in annual medic (Medicago scutellata cv. Robinson) was examined at two locations under dry farming conditions in Kermanshah province, Iran, in 2009. Experiments were conducted based on a randomized complete block design with three replications; the treatments consisted of control (no fertilizer), chemical fertilizer, biological fertilizer and different combinations of chemical and biological fertilizing systems. The results showed that application of different fertilizing systems had a highly significant effect on the number of pods per plant. The highest values were obtained in the treatment using the urea chemical fertilizer + phosphorus-solubilizing bacteria + mycorrhiza. The highest soil seed bank was recorded in the nitrogen-fixing bacteria + phosphorus-solubilizing bacteria treatment; it increased the number of seeds by approximately 50 percent compared to the control (only 134 pod containing seeds). The highest pod yield was obtained after applying nitrogen-fixing bacteria + mycorrhiza (445 kg/ha), the lowest yield in the control treatment (266 kg/ha). In general, under the conditions of this experiment, the seed yield of annual medic var. Robinson receiving nitrogen-fixing + phosphorus-solubilizing bacteria out-yielded other fertilizing treatments. This indicates a synergistic interaction between these groups of bacteria that increases seed yield, the soil seed bank as well as the seed phosphorus uptake of this plant species under dry farming conditions.