Tiller development of winter type wheat Iwainodaichi sown early in the southwestern part of Japan

Winter-type wheat, which isn't injured by frost because the stem elongation begins late, is considered appropriate for early sowing and early harvesti ng in southwestern Japan. The aim of this study is to elucidate the develop mental pattern of tiller in the winter type wheat sown early. Winter type w heat Iwainodaichi and Spring type wheat Chikugoizumi were sown on 5 October (very early sowing), 5 December (early sowing), and 24 December (standard sowing) in 1998. Although the maximum number of tillers per area was greate r in Iwainodaichi than in Chikugoizumi at every sowing time, the number of spikes per area was not greatly different between cultivars. Tillers emerge d regularly as the leaves of main shoot emerged successively. The emergence rate of higher order and position's tillers was larger in Iwainodaichi, th ough most of those tillers became non-productive tillers. The rate of leaf emergence of productive tillers was almost equal to that of the main shoot. On the other hand, that of non-productive tillers became lower gradually a nd stopped. Based on these rules, the change of the number of tillers per i ndividual was investigated. As a result, the time of the maximum number of tillers per individual of Iwainodaichi in early sowing was later than that of Chikugoizumi and earlier than that of Iwainodaichi and Chikugoizumi in s tandard sowing. These changes of the number of tillers per individual seeme d to be affected by the timing of spike development.