SPATIAL GROWTH OF <i>SORGHUM HALEPENSE</i> (L.) PERS.*

Abstract

Summary. Small plants of Sorghum halepense (L.) Pers. were planted in the field and grown without competition from weeds and crops for 2½ years. The plant spread by means of subterranean rhizomes from which aerial shoots developed at increasing distances from the plant centre, and by tillering around these aerial shoots to form clumps. No preferential direction of expansion was detected and established patches developed an approximately circular shape. Aerial growth stopped completely in the cold season. During the warm season the mean area increment amounted to 1·3 m 2 /month and was similar in both years of observations. After 2½ years of growth, patches had extended up to 3·4 m from the initial sprig and had a mean area of 17 m 2 . In the second summer of growth, shoot density reached 190/m 2 and mean seed production was 84 g, or 28 000 seeds per plant. About 80% of rhizome dry weight was present in the upper 20 cm of soil and rhizomes did not penetrate deeper than 40 cm. About 80% of rhizome dry weight was present within 1 m radius from the plant centre. Croissance dans l'espace de Sorghum halepense (L.) Pers.