Time course of root initiation and development in perennial ryegrass – a new perspective

Abstract

Perennial ryegrass (Lolium perenne) tillers of cultivar ‘Alto’ were grown in hydroponic culture in winterspring and autumn experiments and roots of known age were individually dissected and a number of properties including dry weight, main axis length and total length were measured to define root developmental status at successive positions or phytomers on the tiller axis. Root initiation occurred about 5 leaf appearance intervals after leaf emergence at the same phytomer and co-located on the tiller axis with leaf senescence. Root development exhibited co-ordination between successive phytomers as previously described for leaf turnover, but with approximately five adjacent roots developing at any one time. There was little or no root main axis elongation later than six leaf appearance intervals from root initiation, though total length of roots continued to increase for a longer period, especially in autumn.