Investigation of age and application of phosphorus and potassium biological fertilizer on growth characteristics and yield of alfalfa

This study was conducted to investigate the effect of potassium and phosphorus biofertilizers on growth characteristics and yield of alfalfa (cv. ‘Nikshahri’) at different ages.

This combined experiment was conducted as factorial based on a randomized complete block design with three replications during two consecutive years under the climatic conditions of Jiroft, Kerman, Iran. The studied factors included alfalfa age (one, three and five-years old) and bio-fertilizers (Control, Pota-Barvar, Phosphate Barvar II, Pota-Barvar + Phosphate Barvar II). The biofertilizers were used along with irrigation water.

The results of the combined variance analysis showed that there was a significant difference between different ages of alfalfa in terms of some growth characteristics and yield. The highest yield and growth characteristics were related to three-year-old plants and the yield significantly decreased by increasing the age to 5-years old. Based on the results, the highest growth characteristics (except internode length) and yield were related to Pota-Barvar + Phosphate Barvar II treatment, which was not significantly different with Pota-Barvar treatment in term of leaf area index and leaf: stem weight ratio. The interaction effect of age and biofertilizer showed that the combined application of biofertilizers improved the growth characteristics and yield of the older alfalfa plants and the highest yield was found in 3-years old plants treated by combination of both biofertilizers.

The combined application of both biofertilizers (PotaBarvar + Phosphate Barvar II) can be an effective way to prevent alfalfa yield decline in old farms.