Data for: Delayed development of basal spikelets in wheat explains their increased floret abortion and rudimentary nature

Large differences exist in the number of grains per spikelet across an
individual wheat (Triticum aestivum L.) spike. The central spikelets
produce the highest number of grains while apical and basal spikelets are
less productive, and most basal spikelets are commonly only formed
rudimentary. Basal spikelets are delayed in initiation, yet they continue
to develop and produce florets. The precise timings or the cause of their
abortion remains largely unknown. Here, we investigated the underlying
causes of basal spikelet abortion using shading applications in the field.
We found that basal spikelet abortion is likely the consequence of
complete floret abortion, as both occur concurrently and have the same
response to shading treatments. We detected no differences in assimilate
availability across the spike. Instead, we show that the reduced
developmental age of basal florets pre-anthesis is strongly associated
with their increased abortion. Using the developmental age pre-abortion,
we were able to predict final grain set per spikelet across the spike,
alongside the characteristic gradient in the number of grains from basal
to central spikelets. Future efforts to improve spikelet homogeneity
across the spike could thus focus on improving basal spikelet
establishment and increasing floret development rates pre-abortion.