Tillering Potential and Relationship Between Leaf and Tiller Production in Perennial Ryegrass

A detailed morphological examination of the tillering characteristics of perennial ryegrass (Loltum perenne L.) is presented. It is shown that the tillering potential of perennial ryegrass in terms of site filling is 0–693 tillers/tiller/leaf appearance interval. This is higher than earlier presented values and is due to the tillering ability of the prophyll bud which has not previously been taken into account. In a controlled climate room experiment with spaced plants of perennial ryegrass, mean values of site filling were found to be close to this theoretical maximum Due to growth-limiting factors, tiller formation from leaf axillary buds can be delayed or suppressed entirely. A set of equations is presented from which site filling and the ratio of new leaves to new tillers can be calculated for all situations of axillary bud activity. It is stressed that leaf appearance rate can only be determined by marking and counting leaves on single tillers at consecutive dates