Environmental and genetic variation of soybean seed protein content under Central European growing conditions

Seed protein content is important for both feed and food utilisation of soy bean. In soybeans grown in Central Europe, considerable variation in protei n content was due to seasonal influences, as demonstrated in different expe riments from a breeding programme. In soybean genotypes of early maturity g roups, average to high protein content (range 399-476 g kg(-1)) was found i n years with high air temperature and moderate rates of rainfall during the seed-filling period, whereas seed protein content was drastically reduced (range 265-347 g kg(-1)) in seasons of insufficient nitrogen fixation or hi gher amounts of precipitation during seed filling. In a set of 60 genotypes , protein content was increased both by late nitrogen fertilisation before the onset of seed filling and by inoculation of seed with nitrogen-fixing r hizobia. Despite the high degree of environmental modification, genetic var iation of seed protein content was considerable, and genotype,: environment interaction was of low magnitude. Therefore selection of early maturing so ybean genotypes with improved seed protein content appears to be feasible a nd is only limited by the moderately negative correlation between protein c ontent and seed yield. (C) 2000 Society of Chemical Industry.