Forage sorghum quantity and quality as affected by biological phosphorous fertilization

To investigate the effects of seed inoculation with phosphate affecting microorganisms on the quantitative and qualitative traits of two forage sorghum (Sorghum bicolor (L.)), genotypes were investigated during 2011 and 2012 field experiments. The experimental treatments consisted of chemical (triple super phosphate (TP)), and biological P fertilizers [mycorrhizal fungus (Rhizophagus intraradices) (AM) + Pseudomonas fluorescens strain 93 (PB)] as well as sorghum genotypes (Speedfed and Jumbo) factorially arranged on the basis of a randomized complete block design with three replications. The results revealed that seed inoculation by AM fungi and its combined inoculation with PB significantly influenced sorghum growth, P concentration and acid detergent fibre (ADF%). Rhizophagus intraradices appeared to be better adapted for association with sorghum than P. fluorescens strain 93 under the environmental conditions of the experiment. The significant differences in the quantity and quality of the two genotypes as affected by chemical and biological fertilization indicate the importance of selecting the right genotype, which results in higher growth and yields with a better forage quality. Although in most cases, the biological fertilization was the more recommendable, the use of chemical P fertilization up to some level was essential for the production of sorghum forage yield affecting crop quality. It is more beneficial to use the integrated beneficial microorganisms (AM + PB) instead of their single use to achieve better crop growth, yield and nutrient status for both plant and soil health.