Studies on the Tillering of Winter Wheat in Hokkaido: III. Regularity of Tiller Appearance and Varietal Difference

Synchronous emergence of leaf and tiller has been theorized for rice and wheat but not for winter wheat in Hokkaido. This study investigated the pattern of tiller appearance and its difference from synchronous appearance in "Kitahonami", a main winter wheat in Hokkaido for three years. Furthermore, the varietal difference in the pattern of tiller appearance was investigated. In "Kitahonami", concerning the primary-order tillers T1 appeared as expected from the synchronous theory, but T2 and T3 appeared slightly earlier, and T5 and higher tillers later. Concerning the second to fourth-order tillers, all tillers appeared earlier than expected, except for T13. Increase in leaf age after the appearance of tiller was approximately the same at all tillering nodes on the main stem, showing the regularity of synchronous leaf emergence. Tiller appearance was earlier than expected in all varieties examined, but it was later in "Tsurukitchi" than in "Kitahonami" and "Yumechikara". Thus, in winter wheat in Hokkaido tillers appeared earlier than expected from synchronous emerging pattern, and it was earlier from the initial growth stage, It was also found that earliness of tillering in the initial growth stage varied with the variety. Because increased tillering before wintering would increase the number of ears per plant and yield of winter wheat in Hokkaido, earliness of tiller appearance before winter could be useful for effective selection of high-yield varieties.