Occurrence of Plant Growth Inhibitors in Tropical and Subtropical Vegetation.

Acetone, ethanol and water extracts of mature fruits of yaupon (Hex vomitoria Ait.) inhibited germination of mesquite (Prosopis juliflora Swartz DC. var. glandulosa (Torr.) Cockerell, and sorghum (Sorghum bicolor (L.) Moench). Extracts of guava fruit (Psidium guajava L.) inhibited cucumber (Cucumis sativus L.) seed germination. Water soluble inhibitors were found in fruits, leaves, roots and bark of several tropical species representing 10 different families. Strong inhibition of cucumber seed germination and growth did not occur in sand when water extracts containing inhibitors were applied. Growth of corn, sorghum, cucumber and bean was reduced in soils collected beneath Malay apple (Eugenia malaccensis L.) trees. Plant growth-inhibitors occurred in all species studied in various plant parts, and some apparently affect the growth and ecology of other plant species. [ABSTRACT FROM AUTHOR]