抄録
Using clones of Italian ryegrass and perennial ryegrass, the tillering patterns were compared from April to June to know the cause of annuality or perenniality of grasses, with special reference to axillary buds behavior of heading shoots. 1) The relative tillering rate of Italian ryegrass steadily decreased with its development, while that of perennial ryegrass remained almost constant throughout the experimcnt period. 2) In Italian ryegrass not only most tillers that emerged early or late but also the axillary buds formed at the lower nodes of heading shoots turned to reproductive growth at almost the same time, resulting in many heading tillers of different plant height and in small number of vegetative tillers or buds, thus decreasing the relative tillering rate. This situation may promote the seed production and have a keen relation to its annuality. 3) In perennial ryegrass, on the contrary, tiller buds elongated regularly according to a rule, and only a part of tillers which emerged earlier and elongated to a larger height with a greater number of leaves produced heads, remaining the most tillers and tiller buds in vegetative growth stage, which continued to produce new tillers regularly, thus maintainjng its relative tillering rate almost constant, resulting in a greater persistency or perenniality.
