Wheat developmental traits as affected by the interaction between Eps-7D and temperature under contrasting photoperiods with insensitive Ppd-D1 background

Abstract

Earliness per se (Eps) genes are important to fine tune adaptation, and studying their probable pleiotropic effect on wheat yield traits is worthwhile. In addition, it has been shown that some Eps genes interact with temperature. We studied two NILs differing in the newly identified Eps-7D but carrying insensitive Ppd-D1 in the background under three temperature regimes (9, 15 and 18 {degrees}C) and two photoperiods (12 h and 24 h). Eps-7D affected time to anthesis as expected and the Eps-7D-late allele extended both the period before and after terminal spikelet. The interaction effect of Eps-7D x temperature was significant but not cross-over: the magnitude and level of significance of the difference between NILs with the late or early allele was affected by the growing temperature (i.e. difference was least at 18 {degrees}C and largest at 9 {degrees}C), and differences in temperature sensitivity was influenced by photoperiod. Rate of leaf initiation was faster in NIL with Eps-7D-early than with the late allele which compensated for the shorter duration of leaf initiation resulting in similar final leaf number between two NILs. Eps-7D-late consistently increased spike fertility through improving floret primordia survival as a consequence of extending the late reproductive phase.