The growth and yield response of a greenhouse experiments  were conducted  to  investigate soybean plants to colonization by 20 isolates (including G. glomus and 3 Gigaspora species) of vesicular-arbuscular mycorrhizal fungi. Each isolate was evaluated in a high (71kg/fed. Bray-1 P2O5) and a low (21kg/fed. Bray-1 P2O5) fertility soil. Colonization by most Glomus isolates significantly increased plant top dry weight and seed yields. These isolates produced a high increases in dry weigh in the low of soil fertility . Colonization by five of the Gigaspora isolates did not significantly affect top dry weight and seed yield in the high or low fertility soil. The value of comparative testing of species is discussed.