Abstract
Leaf formation of successive tillers was examined with orchardgrass shoots which were developing under sward conditions. The results are summarized as follows. 1) In a sward, the leaf expansion on successive tillers of orchardgrass shoots was multifariously disturbed, and greater part of tillers expanded fewer leaves (Table 2, Fig.1, 2) in contrast with the theoretical value based on the tillering regularity in young normal seedlings which were growing seperately in favorable condition. 2) Above mentioned disturbance of leaf formation was most conspicuous during reproductive growth (from early spring to 1st cut at ear emergence) and growth suppression in hot summar, when regular leaf appearance was rarely observed. 3) As tiller bud elongation was relatively stimulated in autumn, leaf formation advanced rather regularly on each successive tiller, so that a good many of Tn-3, Tn-4, Tn-5 etc. expanded 1st, 2nd, 3rd, etc. leaf, respectively, as same as tillers in normal seedlings mentioned earlier. Neverthless, quite a few of tillers formed during this cool season expanded fewer leaves which were usually shorter than corresponding ones of mother shoot, as compared with theoretical values (Fig.3). 4) Consequently, many types of disterbance of tillering regularity in swards would be merely an effect which is caused by various suppressions of first elongation of tiller buds formed at the upper node of dominantly growing mother shoot.
