Vernalization and photoperiod alleles greatly affected phenological and agronomic traits in bread wheat under autumn and spring sowing conditions

The responses to temperature (vernalization) and day length (photoperiod) in wheat (Triticum aestivum L.) are mainly defined by allelic differences at the respective VRN-1 and PPD-1 loci, which greatly affect wheat phenology and adaptability. Using molecular markers, a panel of 61 diverse bread wheat varieties was genotyped for VRN-1 and PPD-1 alleles, and the traits were evaluated under two conditions by sowing in autumn and spring to investigate the impact of these genes and their alleles on phenological stages, morphological and yield traits. The results revealed that the earlier heading and flowering conferred by the dominant alleles of VRN-1 and the insensitive alleles of PPD-1 genes were consistent under both the autumn and spring sowing conditions. The effects of a single dominant allele of the three VRN-1 genes were similar whereas the effects of a single insensitive allele of the three PPD-1 genes differed, with Ppd-D1a stronger than Ppd-B1a while Ppd-A1a was the least. Varieties sown under spring conditions recorded a larger flag leaf area than those sown under autumn conditions regardless of the allelic influence at the VRN-1 and PPD-1 loci. When compared to other genes, PPD-D1 had a consistent and significant effect on flag leaf area, spike length, and plant height across both sowing conditions. Furthermore, the varieties with Ppd-D1b had larger biomass across both sowing conditions, but this did not translate into increased yield because the Ppd-D1a recorded a higher yield. The impact of PPD-D1 gene on grain yield was evident across both sowing conditions.