DETERMINATION OF TILLER AND ROOT APPEARANCE IN PERENNIAL RYEGRASS (LOLIUM-PERENNE) SWARDS BY OBSERVATION OF THE TILLER AXIS, AND POTENTIAL APPLICATION IN MECHANISTIC MODELING

Recording of bud status at successive phytomers on the tiller axis in perennial ryegrass was shown to provide information similar to that ob tained from conventional recording of tiller appearance by monitoring marked tillers. The technique can be extended to monitor the number of roots formed. These observations lead to the establishment of a notat ion which describes tiller and root appearance, respectively, on the b asis of probability or frequency per phytomer. These statistics are an alogous to but less ambiguous in their interpretation than site fillin g statistics currently used to define tiller, and sometimes root, appe arance. Potential modelling applications of quantifying sward dynamics at the phytomer level are discussed. In particular, nodal frequency s tatistics allow development of mass flow equations to describe leaf, t iller, and root production, and seasonal variation in allocation of ph otosynthate to developing tillers and roots.