LAUSR

Wheat floret development has been a focus of research due to a desire to improve spike fertility, which majorly influences grain yield. Sowing date plays a vital role on grain yield in wheat, and increase in the grain number per spike of winter wheat (Triticum aestivum L.) has been obtained by delayed sowing. During the 2014-2015 and 2015-2016 growing seasons, variation in these developmental patterns was explored involving two winter wheat cultivars (Jimai 22 and Tainong 18) and five sowing dates (September 24, October 1, 8, 15, and 22). We noticed clear differences in the grain number per spikelet; delayed sowing had a greater impact on the number of fertile florets at anthesis than grain set. Significant differences in the developmental patterns of florets among spikelet positions corresponded to variations in the floret developmental rate, with faster floret development associated with higher floret fertility. Delayed sowing did not affect the grain number near the rachis, but significantly promoted grain set on distal florets. Increased spike dry weight (SDW) did not compensate for floret size or grain weight, mainly due to enhanced assimilate partitioning to florets. Delayed sowing significantly affects floret developmental dynamics, causing differences in winter wheat floret fertility. An increased SDW concomitant with improved intra-spike partitioning before anthesis contributes to increase the distal floret numbers per spike and then optimize winter wheat spike fertility. This article is protected by copyright. All rights reserved.