Seasonal development of roots under perennial and annual grass pastures

Abstract

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 tiller 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 rains of the season did not occur until winter. Growth rates of annual ryegrass roots at depth were similar to phalaris in mid spring in the rhizotron. Phalaris had a higher proportion of live roots than cocksfoot prior to the first autumn rain. Cocksfoot did not regenerate a substantial new root system until it developed secondary tillers, about a month after initial rains. Collectively, these studies indicated that the seasonal development and extent of the root systems of cocksfoot and phalaris were different.