SEASONAL DEVELOPMENT OF ROOTS UNDER PERENNIAL AND ANNUAL GRASS PASTURES

Studies in the field and in a rhizotron were conducted to examine the root growth of Phalaris aquatica L. (phalaris), Dactylis glomerata L. (cocksfoot) and Lolium rigidum Gaudin (annual ryegrass). Root and till er development of the perennial grasses in autumn was also studied. In the field, annual ryegrass developed a more extensive surface rooting system than phalaris and cocksfoot by spring in a favourable season. Early root development of annual ryegrass was poor where the first rai ns of the season did not occur until winter. Growth rates of annual ry egrass roots at depth were similar to phalaris in mid spring in the rh izotron. Phalaris had a higher proportion of live roots than cocksfoot prior to the first autumn rain. Cocksfoot did not regenerate a substa ntial new root system until it developed secondary tillers, about a mo nth after initial rains. Collectively, these studies indicated that th e seasonal development and extent of the root systems of cocksfoot and phalaris were different.