Effect of Soil Temperature and pH on Resistance of Soybean to Heterodera glycines

Abstract

Soyabean cultivars resistant to soyabean cyst nematode (SCN), Heterodera glycines are commonly grown in nematode-infested fields. The objective of this study was to examine the stability of SCN resistance in soyabean genotypes at different soil temperatures and pH levels. Reactions of five SCN-resistant genotypes, Peking, Plant Introduction (PI) 88788, Custer Bedford, and Forrest, to SCN races 3, 5, and 14 were studied at 20, 26, and 32°C, and at soil pHs 5.5, 6.5 and 7.5. Soyabean cultivar Essex was included as a susceptible check. Temperature, SCN race, soyabean genotype, and their interactions significantly affected SCN reproduction. The effect of temperature on reproduction was quadratic with the three races producing significantly greater numbers of cysts at 26°C; however, reproduction on resistant genotypes remained at a low level. Higher numbers of females matured at the soil pH levels of 6.5 and 7.5 than at pH 5.5. Across the ranges of temperature and soil pH studied, resistance to SCN in the soyabean genotypes remained stable