Effect of Soil Properties on Local Mycorrhizal Isolates and their Influence on Sesame (Sesamum indicum L.) Growth Traits under Different Moisture Regimes

Abstract

Arbuscular mycorrhizal fungi (AMF) are important components of agricultural ecosystems, and can directly influence the productivity of these systems. Unfortunately, conventional agricultural practices have been shown to adversely affect AM fungi. This study was carried out during the year 2010-2011 to investigate the effect of soil properties on mycorrhizal spore density, and to find out the ameliorative effects of Vesicular Arbuscular Mycorrhizae (VAM) addition on different growth traits of sesame (Sesamum indicum L.); an important cash crop in Sudan economy using two mycorrhizal fungi isolated from date palm trees rhizosphere (from two locations in Khartoum State).VAM inoculation was compared with phosphorus chemical fertilization under different moisture conditions. The study was divided into two parts; a laboratory and a green house experiment. In the laboratory experiment, mycorrhiza from West Omdurman gave a superior spore density (1363 spore/50g soil), while other tested soils gave no significant differences in root infection. This was followed by Soba-2 and Soba-1. All soils have an alkaline reaction. Electrical conductivity in West Omdurman soils is higher than Soba soils. All soils have low CEC ranging from 6-19 cmole/Kg reflecting their low ability to retain soil nutrients. Soba soils are calcareous, while West Omdurman had low CaCO3. As regarding soil texture, both Soba-1 and West Omdurman soils are sandy, while Soba-2 had a clay texture, which might reflect the noticed variability in spore counts between the two soils. Available phosphorus values ranged between 1-2.9 ppm. In the greenhouse experiment, four moisture levels (0%, 20%, 40% and 60%) were used. At 20% moisture level, the data obtained revealed high superiority in all growth traits measured irrespective of the location. The data obtained demonstrated that spore density was higher in West Omdurman, but root infection percent was higher in Soba. The data obtained with the growth parameters were variable but without noticed differences. Inoculation with mycorrhiza showed more efficiency, and were positively reflected in growth traits (plant height, leaf number, dry weight, tissue phosphorus and nitrogen) than addition of mineral phosphorus.