Compatible arbuscular mycorrhizal fungi of Jatropha curcas and spore multiplication using cereal crops

Jatropha curcas is being considered as a biofuel crop for Thailand. Seedlings of J. curcas were used as bait plants to trap compatible arbuscular mycorrhizal fungi (AMF) in field soils in northern Thailand. Of the ten species of AMF that were trapped, two species, Scutellospora heterogama (CMU33) and Entrophospora colombiana (CMU05) produced abundant spores (>50 spores/100 g soil) and heavily colonized the roots of the trap plant. In a second experiment, the two AMF species were used to assess the effectiveness of four annual cereal crop plants (job's tears, Coix lacryma-jobi; rice, Oryza sativa; sorghum, Sorghum bicolor; maize, Zea mays) as suitable nurse plants for AMF spore multiplication. Higher mycorrhizal colonization and spore production were found after 120 days in sorghum than in the other crop species. Spore multiplication did not occur with corn and CMU33, nor with rice and CMU05. Except for the shoots of rice, inoculation increased the root and shoot dry weight of all four crop species. Sorghum is a suitable host for spore multiplication of E. colombiana but an alternative host, with the potential to produce higher spore yields, is required for S. heterogama.