ALLELOPATHIC INHIBITION OF CYNODON-DACTYLON (L) PERS AND OTHER PLANT-SPECIES BY EUPHORBIA-PROSTRATA L

Field observations indicated that Euphorbia prostrata strongly interferes with Cynodon dactylon (L.) Pers. Analysis of some physical and chemical soil factors indicated that competition was not the dominant factor of that interference. Soil collected from under E. prostrata stands was very inhibitory to seed germination and seeding growth of some of the test species including C. Dactylon. This suggests the presence of inhibitory compounds in soil of E. prostrata stands. Subsequent experiments showed that aqueous extract, decaying residues, and root exudates of E. prostrata were inhibitory to most of the test species including C. Dactylon. Thus, it appears that allelopathy is the major component of the interference, with competition probably accentuating its effect. It also was found that allelopathy is an important component of the interference by E. prostrata against Amaranthus retroflexus, Medicago sativa, and Gossypium hirsutum. © 1990 Plenum Publishing Corporation.