Increasing barley yields under future temperature increases

Overall Objective

Under current climatic conditions barley crops experience elevated temperatures in Western Australia during the critical flowering and grain fill growth stages. Temperature event above 30 degrees Celsius significantly reduce a crops yield potential through damage to photosynthetic apparatus and impacting the plants ability to sufficiently fill grain. This project aims to integrate large grained phenotypes into a variety that is able to maintain a larger grain under these types of heat stress events compared to current cultivars. Under future climate conditions heat stress events are going to become more frequent and the impact this will have on barley production in Western Australia is going to become increasingly negative. Currently no research has focused on a maintenance of grain size under heat stress conditions during these two critical growth stages which are the most susceptible to heat.

Through the identification and characterisation of key grain size genes we hope to pyramid all identified genes into an elite background that meets the desired objective of the project. This work will ideally culminate in germplasm that can be disseminated to breeding companies for inclusion in their breeding programs. We also will have developed diagnostic markers for grain size and maintenance of grain size under heat stress conditions.

Project Synopsis

Researchers at Murdoch University have used a process termed ‘marker assisted selection’ coupled with speed breeding (multiple generations per year) to breed a larger grained and higher yielding barley variety.  In order to increase the grain size of barley via marker assisted selection the genetic regions which influence grain size need to be identified and understood. Research conducted during Calum Watt’s Ph.D. has aimed to identify these regions and understand the mechanisms involved in grain size regulation.  During his Ph.D. Calum identified multiple significant regions that increase grain size and has subsequently used genetic resources developed during his research to improve the grain size and yield potential of barley by incorporating genetic regions that positively influence grain size among other traits such as scald and net blotch resistance into an elite genetic background using speed breeding and marker assisted selection.

A driving force for this COGGO supported project was to promote the transition of leading research into application that will benefit barley producers and users in Western Australia.  Despite Western Australia growing a substantial amount of barley, as a crop it is largely under-researched when compared to wheat for example.  However, in our production regions they both face similar constraints and if we are to address yield and quality reductions in the present and future, more research needs to address the effect of constraints on barley production. Increasing the size of the grain relates to increasing the ‘sink’, by genetically improving the size of the sink we, in essence, are trying to increase the grain weight.

The impact of drought is widely understood, but the role of heat stress events (>35 ^oC) during flowering and grain fill less so.  We know from research in other cereal crops that heat stress during these critical growth stages can significantly impact the source (leaves) to sink (grain) relationship and reduce yield and quality (higher screenings).  Reducing the likelihood of screenings by improving the grain size of a variety through genetic means has the potential to buffer against yield and quality losses when a crop experiences stress events.

The researchers aim to deliver the genetic material developed in this project to the barley breeding companies so that the west Australian barley industry can benefit from improved productivity in an uncertain future.