Perennial Glycine species exhibit a number of characteristics of agronomic potential including daylength neutrality, tolerance to heat, drought, cold (Marshall and Broue, 1981) and salinity (Newell and Hymowitz, 1982), and resistance to soybean cyst nematode (Riggs and Hamblen, 1962, 1966), yellow mosaic virus (Singh et al., 1974), powdery mildew (Mignucci and Chamberlain, 1978) and rust (Burdon and Marshall, 1981). Each of these features would be useful if introgressed into the soybean genepool. However, to date, it has only been possible to produce a few sterile hybrids using conventional crossing followed by embryo rescue (see Newell et al., 1987)
