Spike growth affects spike fertility through the number of florets with green anthers before floret abortion in wheat

The dynamics of floret initiation/abortion has been explored widely; however, the mechanisms of increasing floret fertility at anthesis in wheat production remain unclear. In this study, morphological and physiological responses of florets per spikelet and per spike to nitrogen and irrigation treatments in the field were investigated. Each spikelet produced the maximum number of living floret primordia (MFP) and showed no difference between treatments at the W7.5 stage; this ability was hardly affected by treatments. We firstly found that gradually abortive florets during W8.5-W10 stages were delayed due to improving assimilates availability in the spike instead of the 4th-5th inthernode; in fact, these florets would be aborted completely and never become fertile florets. Notably, we found that those florets in which the anther turned green (value ≥ 97) at W7.5 always became fertile, and their number showed a significant positive relationship with number of fertile florets (NFF) at W10. Collectively, more available assimilates in spike accelerated anther turning green during period of early floret development, maintained their development normally and becoming fertile florets, but did not make florets that initiate abortion become fertile florets and increase the MFP.