Differential activity of allelochemicals from Secale cereale in seedling bioassays

Differential activities of BOA, DIBOA, and crude water extract of Secale ce reale 'Elbon' were studied in culture dish bioassays using several vegetabl e and weed species. On average, DIBOA was about seven times more inhibitory to root growth and four times more inhibitory to shoot growth than BOA. Al lelochemicals from S. cereale inhibited shoot more than root elongation of cucurbits Cucumis melo, Cucumis sativus, and Cucurbita pepo. Small-seeded c rops Lycopersicon esculentum and Lactuca sativa were sensitive to S. cereal e. Large-seeded crops, including the cucurbits and Zea mays var. rogusa, we re tolerant. Among the small-seeded weeds Amaranthus palmeri, Digitaria san guinalis, Echinochloa crus-galli, and Eleusine indica, E. crus-galli was le ast susceptible. Inhibition of germination by BOA or DIBOA occurred only in small- to medium-seeded species, including A. palmeri, D. sanguinalis, E. indica, L. sativa, L. esculentum, and Sida spinosa. Large-seeded species C. melo, C. sativus, C. melopepo, Z. mays var. rogusa, Ipomoea hederacea var. integriuscula, Ipomoea lacunosa, and Senna obtusifolia were tolerant to al lelochemicals from S. cereale. This bioassay indicated a promising potentia l for controlling small-seeded weeds in large-seeded crops.