Vernalisation and photoperiod responses of diverse wheat genotypes

Abstract

Context: Wheat (Triticum aestivum L.) adaptation is highly dependent on crop lifecycle duration, particularly the time at which flowering occurs in a specific environment. Frost, low solar radiation, heat and drought can significantly reduce yield if a crop flowers too early or late. Wheat genotypes have different lifecycle durations determined by plant responses to temperature (thermal time accumulation and vernalisation) and photoperiod. These responses are largely controlled by five phenology genes (two PPD1 and three VRN1 genes). Advances in crop phenology modelling suggest that flowering time under field conditions could be accurately predicted with parameters derived from photoperiod and vernalisation responses obtained in controlled environments. Aims: This study quantified photoperiod and vernalisation responses of 69 Australian wheat genotypes selected for diversity at the PPD1 and VRN1 loci. Methods: Spring and winter genotypes were grown in four controlled environments at a constant temperature of 22°C with photoperiod (17 or 8 h) and vernalisation (0 or 8 weeks) treatments as factors. Key results: Thermal time from coleoptile emergence to flowering in spring genotypes was typically decreased more by long photoperiod than by vernalisation; the opposite was true for winter genotypes. Spring genotypes that were sensitive to vernalisation contained a sensitive allele at the Vrn-A1 locus. Conclusions: There is large diversity in phenological responses of wheat genotypes to photoperiod and vernalisation, including among those with matching multi-locus genotype. Implications: Data from this study will be used to parameterise and test a wheat phenology model in a future study.