Arbuscular mycorrhizal dependency and phosphorus responsiveness of released, landrace and wild Sudanese sorghum genotypes

Abstract

Enhanced P acquisition efficiency and arbuscular mycorrhizal fungi (AMF) dependency in sorghum are relevant for low-input agroecosystems. The objective of this work was to determine the genetic variation in mycorrhizal and P dependency. Five Sudanese sorghum (Sorghum bicolor (L.) Moench) genotypes representing released, landrace and wild forms were cultured with or without AMF (Rhizophagus irregularis) and with or without P fertilization in a growth chamber. Sorghum growth attributes, net photosynthesis, shoot N and P concentrations and AMF colonization were measured 30 days after sowing. The released cultivar Tabat showed higher AMF colonization as well as mycorrhizal and P growth responses compared with the landraces and wilds. Addition of P reduced AMF dependency for shoot dry weight and shoot P concentrations. The AMF inoculated released cultivar Tabat and landraces had significantly higher net photosynthesis than non-mycorrhizal plants. A clear-cut genetic variation was detected for the first time within Sudanese sorghums in their responsiveness to AMF and P. There were no indications that modern breeding programs generally have adverse effects on mycorrhizal growth response.