Yield loss caused by soybean cyst nematode, Heterodera glycines, in Iran

The soybean cyst nematode, Heterodera glycines, is of major economic importance and widely distributed throughout the world. The effect of H. glycines HG Type 0 on seed yield of susceptible and resistant soybean cultivars was assessed with and without nematicide application in two naturally infested fields in Iran. Soybean cvs BP (susceptible) and DPX (resistant) were arranged in a randomised complete block design and fenamiphos 10G was used in-furrow as a treatment. The population levels of eggs and second-stage juveniles of H. glycines were determined in soil samples collected at planting and harvesting time. Although no above-ground symptoms of nematode infection were visible, mean yield was 48% greater for the resistant cultivar compared with the susceptible cultivar. The yield of cv. BP increased by 16% in plots treated with fenamiphos compared with untreated plots. The resistant cultivar suppressed the reproduction rate of H. glycines. Seed composition, including protein and oil, did not show significant differences between resistant and susceptible cultivars. This is the first demonstration of the yield loss caused by the soybean cyst nematode in Iran.