| Defining the genetic basis of barley metabolite content to improve nutrient use efficiency, crop quality and resilience with reduced inputs |
| Student: George Epaku Industry partner: Scotch Whisky Research Institute Supervisors: Dr Will Allwood, Dr Kelly Houston, Professor Tim George (JHI); Dr Piers Hemsley (UoD); Dr Barry Harrison (SWRI) |
| Objectives |
| Nitrogen use efficiency (NUE) is the ability of a crop to yield sufficiently under N deprivation. This is beneficial in parts of the world with limited access to nitrogenous fertilisers, but also reduces crop production costs while protecting the environment against nitrous oxide emissions, eutrophication, and other negative effects of excessive fertiliser application. Depending on the location and intended final use, barley crop mineral supplementation programmes recommend up to 120Kg N/Ha for current varieties. Barley crops utilise only 30% – 40% of the N applied leaving over 50% of these dominantly inorganic N forms free and at risk of polluting the environment. Developing NUE barley varieties is, therefore, one of the sustainable remedial strategies that could reverse this trend while upholding food security and livelihoods. Aside from yield, NUE includes quality for example in the malting industry where grain needs to have acceptable levels of both carbohydrate (sugars) and protein (e.g. amylase). Barley for malting is considered of good quality if grain nitrogen does not exceed 1.85%. As such, developing NUE barley varieties for such a lucrative industry requires an understanding of the balance between carbon and nitrogen metabolism under N deprivation in the crop, and establishing whether this balance is linked to genetic composition for ease of selection and breeding. Our study, therefore, aims at establishing the genetic control for barley’s metabolic adaptation to reduced N input conditions with the general objective of contributing knowledge towards developing NUE barley varieties bearing desirable malting quality attributes. Specifically, the study aims at assessing the genetic component for adaptation to reduced N inputs, exploring the balance between carbon and N metabolism in barley under such conditions, and linking these genetic and metabolic profiles. |
| Progress to date |
| Two hundred and sixty-three diverse, and six barley genotypes, have been treated with reduced and optimum N for malting barley under field and green-house conditions, respectively. Generally, N supplementation resulted in greater total yields under green-house conditions. However, grain morphology measurements with implications on malting quality such as thousand grain weight showed limited difference between optimal and reduced N input under green-house conditions. Leaf and grain amino acid content were reduced with N deprivation, grain sugars were greater under N deprivation, whereas leaf sugars were greater under N supplementation. We hypothesize that plants grown under N deprivation invest higher levels of sugars into their grains, since fewer grains are produced. This could be considered as a survival mechanism to maintain higher grain quality. More still, the metabolic constitution of the plants especially under N deprivation showed strong linkage to how they grouped at a genetic level. Under field conditions, agronomic traits such as tiller counts, plant heights, and yield have so far been measured with grain quality traits such as thousand grain weight and carbohydrate: protein ratios to follow. |
| Future plans |
| After collecting these data over two growing seasons, we shall attempt to identify genes underpinning NUE in malt barley, alongside identifying some of the best and worst performing varieties that we shall then use to understand how barley is able to balance its carbohydrate and protein constitutions under N deprivation. |