CROP-ROTATION .19. EFFECTS OF WINTER CROPS ON YIELD AND ON SOME AGRONOMIC CHARACTERISTICS OF SOYBEAN PLANTS

During a five-years period at EMBRAPA/Centro Nacional de Pesquisa de Trigo (CNPT) in Passo Fundo, RS, Brazil, the productivity and some agronomic characteristics of soybean (Glycine max Merril) plants in succession of winter crops were assessed. soybeans were directly seeded on oats, rapeseed, flax, lupin and wheat stubble. The winter crop followed a rotation schedule and was arranged in a complete randomized block design and replicated four times. Both sowing and harvesting were mechanically done in plots with 120 m2. The means for soybean yield and insertion of the first pods were not affected by winter crops; nevertheless, yield components (number of legumes, number of grains, and grain weight/plant), 1,000 grain weight, final stand and , plant height were influenced by preceding winter crops.