INTERFERENCE FROM BROCCOLI RESIDUE ON BRASSICA GERMINATION AND SEEDLING GROWTH

Germination bioassays were conducted to assess if water-soluble extrac ts of broccoli (Brassica oleracea L, var, italica L,) affect germinati on of broccoli, cabbage (Brassica oleracea I,, var. capitata L.), and cauliflower (Brassica oleracea L. var, botrytis L.). Greenhouse experi ments also examined the phytotoxic potential of soil previously croppe d with broccoli and broccoli plant parts on seedling growth of those s pecies, The first bioassay used nonsterile extracts (NSEs) and filter- sterilized extracts (FSEs) of broccoli leaves, The second bioassay use d nonsterile and filter-sterilized leaf extracts (LEs), stem and root extracts (SREs), and whole broccoli plant (leaves, stems, and roots) e xtracts (WPEs), Broccoli and cabbage germination were not affected by NSEs or FSEs, but the latter reduced cauliflower germination by 22%, L Es and SREs decreased germination speed for broccoli, cabbage and caul iflower, Greenhouse seedlings were grown in soil previously cropped wi th broccoli or fallow soil at three fertilizer levels, Broccoli soil w as phytotoxic to cauliflower but enhanced broccoli and cabbage seedlin g growth, The differential sensitivity to broccoli plant residue was i n the order of cauliflower > broccoli = cabbage, with SR residue havin g the highest phytotoxic potential.