Effect of Ppd and Vrn genes on important agronomic traits of bread wheat (Triticum aestivum L.)

ObjectiveEarly heading as an adaptation mechanism for end season heat and drought stress is an important goal in wheat breeding programs. Photoperiod (Ppd) and vernalization (Vrn) are the most important genes controlling early heading in bread wheat. The aim of the present study was to investigate the effect of Ppd and Vrn genes on early heading, grain yield and important agronomic traits in BC4F2 generation of Roshan (recurrent parent) and Excalibur backcross.Materials and methodsA BC4F2 population resulted from backcross of Roshan and Excalibur was generated in Shahid Bahonar University of Kerman. In this breeding program, early heading was transferred from Excalibur cultivar to Roshan (recurrent parent). This population, including 175 BC4F2 progenies, and their parents were cultivated in the research field of Shahid Bahonar University of Kerman in the 2019-2020 growing season. The progenies were genotyping using specific markers Vrn-B1, Vrn-D1 and Ppd-D1. In this population, early heading, grain yield and important agronomic traits were evaluated.ResultsExcalibur and Roshan had Ppd-D1a, and Ppd-D1b alleles, respectively. The frequency of Ppd-D1a/Ppd-D1a and heterozygous genotypes in the evaluated population were 27.33% and 415%, respectively. In this population, Ppd-D1a/Ppd-D1a, which is photoperiod insensitive genotype, was 6 and 4 days earlier heading than Ppd-D1b/Ppd-D1b and Ppd-D1a/Ppd-D1b genotypes, respectively. There was no allelic diversity between progeny for Vrn-1 locus. Early heading had a significant negative correlation with grain yield, 1000-grain weight, spikes number and grains number per spike.ConclusionsThe results confirm the importance of Ppd-D1a gene in the early heading, grain yield and yield components. Selection for early heading increased grain yield, 1000-grain weight, spikes number, biological yield, stover biomass at harvest and spikes dry weight. Due to the large and significant effect of Ppd-D1a gene on grain yield and yield components, we recommend marker assisted selection of this gene in wheat breeding programs. Phenotypic selection was performed before BC4F2 generation and Vrn gene diversity was established in the population.