ScienceAsia 9 (1983): 037-045 |doi: 10.2306/scienceasia1513-1874.1983.09.037

COMPETITION BETWEEN UPLAND RICE (ORYZA SATIVA L. VAR. GATI AND SPINY PIGWEED (AMARANTHUS SPINOSUS L.)

A. THONGPUKDEE^a and J.H.H. EUSSEN^b

ABSTRACT: Replacement series experiments, in which two plant species are grown in monocultures and in mixtures, provide information on whether both plant species utilize the same complex of environmental factors or 'space', Upland rice(Oryza sativa L. var. Gati) and spiny pigweed (Amarantus spinosus L.) were grown as monoculture at a density of 1,2,3,4,5 and 1, 2, 4, 8, 16,32 plants/pot respectively, In the mixtures, the density of the upland rice wasflXed (2 plants/pot) and that of spiny pigweed varied (1, 2, 4, 8, 16 plants/pot). The spiny pigweed was highly competitive even when growing at the ratio 1:2. At 60 days of growing both plants together, a reduction of 79 % and 84 % of dry matter of the aerial and root parts respectively were found in the upland rice.

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a. Department of Biology, Faculty of Science, Silpakom University, Nakhon Pathom, Thailand.
b. Botanical Laboratory, Lange, Nieuwstraat, 106 Utrecht, Netheriands.

Received 15 December 1982