Specific adaptation for early maturity and height stability in Icelandic spring barley

Magnus Göransson,Therése Bengtsson,Åsmund Bjørnstad,Jón Hallsteinn Hallsson,Morten Lillemo

doi:10.1002/csc2.20459

Abstract

AbstractCereal production in important growing regions is negatively influenced by climate change. This can be countered by expanding cereal production northwards in Scandinavia and Iceland, where today, barley (Hordeum vulgare L.) is primarily used as feed, as it rarely reaches malting quality. This study explores genetic factors underlying the ability of barley to mature fully in low temperature and long photoperiod. A panel of 84 spring barley lines were grown in controlled environments with different day lengths and temperatures, partially mimicking the target environment. The panel was screened for accumulated heat sum to heading, maturity, and height, all traits of importance for adaptation to the northern periphery. Subgroups with different stability and heat sum requirements were found, and day‐length‐neutral lines were identified. Height was temperature controlled, with lower temperature resulting in taller plants. The results were coupled to a genome‐wide association study (GWAS). Despite the small panel size, the Mat‐a locus was identified to have the strongest association with heat sum to heading; Ppd‐H1, Mat‐a, FT1, and DHAR2 with heat sum to maturity; and GA20ox1 with height. Early maturing lines with height stability have successfully been developed in Iceland, and this study confirms their performance in controlled environments for the first time. It provides insight to the mechanisms behind early maturity that will increase our ability to further adapt barley and other cereals to the northern climate. This will facilitate breeding work toward combining early maturity and height stability with traits such as quality, further enabling the northward expansion of grain production.

Highlights

Barley (Hordeum vulgare L.) is the most widely adapted of the cereals (Ullrich, 2011) and, as such, is better suited to many marginal areas than, for example, wheat (Triticum aestivum L.)
The data from all four environments were significantly positively correlated among each trait, the range of r values were 0.55–0.82, 0.24–0.65, and 0.4–0.86 for heat sum to heading (HSHD), heat sum to maturity (HSMD), and height, respectively (Supplemental Figure S3)
The lines that did not head in short day warm (SDW) grouped in the top right corner

Summary

Introduction

Barley (Hordeum vulgare L.) is the most widely adapted of the cereals (Ullrich, 2011) and, as such, is better suited to many marginal areas than, for example, wheat (Triticum aestivum L.). Breeding of cultivars better adapted to local environments could potentially close the yield gap in northern latitudes. Iceland is at the margin of possible barley cultivation with a low temperature and a long photoperiod, the warmest month of the year averages 11 ̊C (Icelandic Meteorological Office). Because of its maritime climate, the accumulated heat sum during the growing season is lower in Iceland than other regions at comparable latitudes (Martin et al, 2017) especially during the grain-filling period in late summer and early fall. Hilmarsson et al, 2017) has pinpointed the most limiting factor in the northernmost areas of barley cultivation to be the ability to reach maturity in low temperature. The flowering time is important, as a plant flowering too early may risk damage during anthesis because of late spring frosts, whereas flowering too late may risk that the crop does not fully mature before harvest (Bragason, 1985)

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