Khadr F.G.M.A. author text journal article 1999 The effect of Euphorbia scordifolia and Hordeum leporinum competition on leaf area development, radiant energy absorption, and dry matter production was evaluated in a field experiment. Profile measurements (0-0.3, 0.3-0.6, 0.6-0.9, and >0.9 m above ground) of absorbed photosynthetically active radiation (APAR) and leaf area index (LAI) by species were taken at four densities of E. scordifolia (0, 1, 4, and 12 plants per m²). APAR calculated for H. leporinum in mixed communities was 79, 77, and 49 % of the APAR in H. leporinum and LAI was reduced to 81, 65, and 37 %. LAI of H. leporinum was concentrated in the 0.3-0.6 m layer, while the taller E. scordifolia plants had the greatest LAI above 0.6 m. By absorbing radiant energy in the upper canopy, E. scordifolia reduced APAR penetrating to H. leporinum. Measurements of net photosynthetic and transpiration rates, leaf temperature, and stomatal conductance confirmed the importance of competition for PAR for plant growth and metabolism. dry mass; leaf area index; leaf temperature; net photosynthetic rate; plant density; stomatal conductance; transpiration 10.1023/A:1007087903674 https://ps.ueb.cas.cz/artkey/phs-199904-0007.php https://ps.ueb.cas.cz/artkey/phs-199904-0007.php continuing 36 4 525 531 1999 03003604 periodical academic journal