Diverse Physiological and Physical Responses among Wild, Landrace and Elite Barley Varieties Point to Novel Breeding Opportunities

Jim Stevens,Tracy Lawson,Matthew Alan Jones

doi:10.3390/agronomy11050921

Abstract

Climate change from elevated [CO2] may reduce water availability to crops through changes in precipitation and higher temperatures. However, agriculture already accounts for 70% of human consumption of water. Stomata, pores in the leaf surface, mediate exchange of water and CO2 for the plant. In crops including barley, the speed of stomatal response to changing environmental conditions is as important as maximal responses and can thus affect water use efficiency. Wild barleys and landraces which predate modern elite lines offer the breeder the potential to find unexploited genetic diversity. This study aimed to characterize natural variation in stomatal anatomy and leaf physiology and to link these variations to yield. Wild, landrace and elite barleys were grown in a polytunnel and a controlled environment chamber. Physiological responses to changing environments were measured, along with stomatal anatomy and yield. The elite barley lines did not have the fastest or largest physiological responses to light nor always the highest yields. There was variation in stomatal anatomy, but no link between stomatal size and density. The evidence suggests that high photosynthetic capacity does not translate into yield, and that landraces and wild barleys have unexploited physiological responses that should interest breeders.

Highlights

Rising concentrations of greenhouse gases including CO2 ([CO2]) are expected to raise global mean surface temperatures by 3 ◦C above the baseline by the end of this century [1,2]
The aim of this study was to characterise natural variation in stomatal anatomy and leaf physiology of wild barleys and landraces relative to elite varieties grown in both field and controlled environments to understand the extent of variation in gs, and A in non-elite cultivars compared to commercial varieties and assess the impact of stomatal responses on these
This study showed that there was no link between stomatal size and density and that the non-elite barley lines possessed physiological traits that would be attractive to breeders

Summary

Introduction

Rising concentrations of greenhouse gases including CO2 ([CO2]) are expected to raise global mean surface temperatures by 3 ◦C above the baseline by the end of this century [1,2]. The global population is expected to rise from 7.2 to 9.6 billion by 2050 [3] putting increasing pressure on food production. Widespread use of biofuels and changing dietary preferences along with rising urbanisation [5,6] are adding pressure to raise yields in the key crops including rice, wheat and maize that are responsible for the vast majority of all calories consumed globally [7]. As a result of climate-induced surface temperature increases, photosynthesis could be reduced in some temperature-sensitive plants (dependent on species and variety), decreasing productivity [8]. High vapour pressure deficit (VPD) acts in addition to direct temperature effects on evapotranspiration by reducing gs [10,12]

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