The Effect of Light and Temperature on the Growth and Development of Johnsongrass

Johnsongrass [ Sorghum halepense (L.) Pers.] was grown for 4, 8, and 12 weeks at 24, 32, and 40 C at 9, 13, and 19 klux illumination. Maximum growth and development after 12 weeks were obtained at 32 C and 19 klux. Maximum leaf growth and development were obtained at 32 C and 9 klux. Primary culm height and weight were greater at 24 C than at 40 C, regardless of the illumination, whereas secondary culm height and weight were greater at 40 C than at 24 C. Secondary culm production increased at 40 C and decreased at 24 C. Root and rhizome development increased with increasing light intensity. Growth of roots and rhizomes was maximum at 32 C and minimum at 40 C.