Manure Application Rate and Solubilizing Bacteria Influence On Alfalfa Seed Yield and Yield Components in Semi-Saline Soil.

Phosphorus is an essential nutrient element required for plant growth and development. However, low solubility of phosphorus in soils makes it a growth-limiting nutrient. Phosphate-solublizing microorganisms may play an important role in mediating the mobility of phosphorus thus enhancing the availability of phosphorus to plants. Lucern (Medicago sativa L.) is widely grown in almost all regions of Iran as a forage crop due to its high yield potentials, protein content and palatability. An experiment was laid out in a three-replicated split-split plot design with four cow manure application rates as main plots, three phosphorus solubilizing bacteria (9, and 41 strains plus no bacteria) in sub-plots and three alfalfa seeding rates (2, 6 and 10 kg ha^-1) in sub-sub plots. Seed yield improved with increasing manure application up to 30 tons per hectare. Seed yield improved by 9% when inoculated with bacteria strain 41 whereas bacteria strain 9 did not enhance the seed yield. Improvement of seed yield was primarily due to 2% increase in average seed weight. The response of seed yield to seeding rate was asymptotic where maximum yield obtained from seeding rate of 6 kg ha^-1. Results of this experiment showed that the application of 30 tons of manure and bacteria 41 and 6 kg ha^-1 seeding rate produced the highest seed yield of 414 kg ha^-1 under semi-saline condition.