Abstract
A recombinant inbred durum wheat population was grown under three contrasting regimes: long days following vernalization (LDV), long days without vernalization (LD), and short days following vernalization (SDV). The length of several pre-anthesis stages and the number of leaves and the phyllochron were measured. Different groups of genes were involved in determining the phenology in the three treatments, as demonstrated by a quantitative trait locus (QTL) analysis. The length of the period required to reach the terminal spikelet stage was correlated with the time to anthesis only in the case of LDV- and LD-grown plants where the timing of anthesis depended on the final leaf number. However, for SDV-grown plants, anthesis date was more dependent on the length of the period between the terminal spikelet stage and anthesis and was independent of leaf number. The involvement of the phyllochron in determining the duration of pre-anthesis development was also treatment-dependent. QTL mapping of the various flowering time associated traits uncovered some novel loci (such as those associated with the phyllochron), in addition to confirming the presence of several well-established loci.
Highlights
Flowering time is an important determinant of grain yield (Reynolds et al, 2009), and its manipulation is a common breeding target
The length of the period required to reach the terminal spikelet stage was correlated with the time to anthesis only in the case of long days following vernalization (LDV)- and long days without vernalization (LD)-grown plants where the timing of anthesis depended on the final leaf number
Following the May transplanting (LDV and LD), it peaked at 15.2 h, around the mean of the time when the recombinant inbred lines (RILs) had reached TS
Summary
Flowering time is an important determinant of grain yield (Reynolds et al, 2009), and its manipulation is a common breeding target. Studies of the genetic determination of flowering time in wheat have demonstrated that it is controlled by at least 20 genes, scattered over the whole genome (Snape et al, 1996; Koornneef et al, 1998); these genes have been classified according to whether they respond to vernalization or to photoperiod or whether they confer earliness per se (EPS; Worland, 1996; Law and Worland, 1997; Laurie et al, 2004). The period during which most of the growth of the wheat spike occurs coincides with the stem elongation stage, so lengthening the latter can be expected to increase the size of the spike and, by implication, the number of potential grains that are set (Halloran and Pennell, 1982; Slafer et al, 1996; Slafer and Whitechurch, 2001). The ability to fine-tune crop phenology offers some potential to increase spike fertility (Fischer, 2011; Foulkes et al, 2011; García et al, 2011)
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