Genetic Analysis of Flowering Time of Ethiopian Barley Accessions Under Field and Climate Chamber Conditions

The flowering time is one of the traits strongly influencing grain yield. In barley, the flowering time is mostly determined by the photoperiod, vernalization, and timely rainfall. As Ethiopia is located near the equator, the photoperiod and vernalization have a minimum effect on barley, but rainfall and temperatures are major challenges. In this study, 260 Ethiopian barley accessions were evaluated for flowering time at four different locations in Ethiopia in three years. Additionally, a set of 196 accessions was evaluated in climate chambers with corresponding environmental parameters. According to the results, the sum of the daily temperature of growing days strongly influenced the flowering time. The mean flowering time of the warmer Melkassa location was 15, 7, and 4 days earlier than of the cooler Holetta location and the less warm Debrezeit and Dera locations, respectively. On the other hand, the flowering time in the climate chamber was delayed by 52 and 37 days than that at the Melkassa and Holetta locations, respectively; its lowest average daily temperature (18 ◦C), compared to Melkassa (28.0 ◦C) and Holetta (22.1 ◦C), might be the reason. GWAS identified MTAs on chromosomes 5H at 571.62 to 572.54 Mb as strongly associated with the flowering time at warm locations (Melkassa, Dera, and Debrezeit); MTAs on chromosome 2H at 25.1 and 29.3 Mb turned out to be associated with the flowering time at Holetta and in the climate chamber, respectively. Important factors that influence the flowering times of Ethiopian barley landraces and associated SNP markers are identified in this study, which might be useful to consider in future barley breeding programs.