The Development of Coleoptile Tillers in Relation to Seedling Vigor in Early-Maturing Varieties of Spring Type Wheat

Increase in seedling vigor is necessary to improve the yield of early-maturing spring wheat with a limited growth period. The importance of coleoptile tillers in increasing seedling vigor has been suggested. However, most previous studies on the development of coleoptile tillers have been made with only a limited number of varieties and under controlled environmental conditions. In this study, we examined difference in the development of coleoptile tillers among early-maturing varieties of wheat under field conditions. We observed large differences among varieties in the percentage of plants with coleoptile tillers, ranging from 5.6% in Haruyutaka to 60.1% in Bandouwase. The percentage of plants with coleoptile tillers was closely correlated with the number of leaves developed on the main stem. The dry weight of the plants with coleoptile tillers was heavier than that without coleoptile tillers (by 34.8% in Fukuwase komugi). However, in some varieties, the dry weight of the plants with coleoptile tillers was similar to that of plants without coleoptile tillers. The increase in dry weight per plant seemed to be achieved by the production of either a few heavy tillers or many light tillers.