Abstract
In naked barley, grain yield is increased by increasing the amount of topdressing at the spike formation stage (SFS) due to the increase in spike number. We investigated the number of emerged tillers, the nodal position of the emerged tillers and the characters concerned with productivity of tillers in cultivar “Toyonokaze” in order to clarify how the topdressing at SFS increases the spike number. We prepared five nitrogen topdressing patterns in 2012/2013 and three in 2013/2014, differing in amounts of basal dressing or topdressing at SFS. Increasing topdressing at SFS increased the number of plants with emerging tillers and also that of plants with tillers emerging at a high nodal position. The heavier topdressing at SFS increased the rate of plants emerging tillers at a higher nodal position compared to the lighter topdressing at SFS with the same amount of total fertilizer. The productive tillers expanded 5 – 8 leaves and the dry weight of these tillers was more than 1000 mg. The water soluble carbohydrate content of productive tillers was 10 – 20% while the content was more than 20% in some of the heavy non-productive tillers and less than 10% in some of the lighter non-productive tillers. Heavier topdressing at SFS, increased the number of plants with emerging primary tillers at the 1st, 3rd and 4th nodal positions. Most of the primary tillers emerged at the 1st nodal position became productive and these plants had more than two productive tillers including the main stems.
