Effect of selection for Ppd-D1a gene and early heading on important agronomic trait of bread wheat (Triticum aestivum L.)

 Photoperiod controlling genes (Ppd) are the most important genes groups that modify early heading in bread wheat. The aim of this research was to evaluate Ppd genes in Iranian cultivars, and also assessing the effect of Ppd-D1a on earliness trait.

Material and methods

 Earliness was transferred from Excalibur to Kalhaydari, Roshan and Mahdavi cultivars using backcross method to generate BC1F3 generation. Three photoperiod controlling genes including Ppd-A1, Ppd-B1 and Ppd-D1 were assessed in Iranian cultivars using PCR by specific primers. Bulk segregation analysis of Ppd-D1 loci was done for early heading genotypes in three populations. Two years field evaluation were conducted to show the effect of selection for earliness on important agronomic traits of bread wheat.

 Mahdavi, Ghods, Kalhaydari, Sardari, Roshan, Kavir, Excalibur and Shahpasand were containing Ppd-A1b and Ppd-B1b. Kalhaydari, Sardari, Roshan and Kavir were containing Ppd-D1b, while Mahdavi, Ghods, Excalibur and Shahpasand were possessed Ppd-D1a. Bulk segregation analysis of 10% of the earliest heading BC1F3 populations showed that early heading progenies were possessing Ppd-D1a. Positive significant correlation was observed between early heading and earliness. Meanwhile, days to heading had a negative correlation with grain filling period. Longer grain filling period improved 1000-grain weight, grain number per plant and grain yield. Selection for early heading improved plant height, leaf size, spike number per plant, seed number per plant, 1000-grain weight and grain yield, while decreased spike length, awn length and infertile tiller number.

 Marker assisted selection or marker assisted backcross of Ppd-D1a gene could improve earliness in bread wheat. Early heading was improved in Roshan, Kalhaydari and Mahdavi background for 13, 14 and 1o days, respectively. Selection for early heading improved the most important grain yield related agronomic traits in Kerman condition.