Perennial grasses for marginal soils
Perennial grasses, which, once established, can be harvested and re-grown annually, have a number of other beneficial characteristics that suit them as biomass crops. These include high resource-use efficiency, high-productivity, good environmental qualities and a wide range of end uses.
Environmental benefits include high rates of soil carbon sequestration, enhanced biodiversity and soil stabilisation.
Furthermore, perennial grasses naturally colonise marginal areas of land, which often impose severe restrictions on the growth of vegetation. Marginal land is defined as land of poor quality for agriculture that yields poor returns for the farmer. Marginal conditions comprise, for example, poorly drained soils, soils with high salt
concentrations, sites prone to severe cold and frost stress and drought prone sites.
The aim of the GrassMargins project is to identify, characterise and develop novel varieties of C3 cool season grasses (Dactylis glomerata, Festuca arundinacea
and Phalaris arundinacea) and the C4warm season genus Miscanthus that show high and stable productivity and require the minimum of additional inputs when grown on different forms of marginal land. These species were selected since they are known from previous work to adapt well to temperate and colder climate conditions.
The major elements of the project are as follows
• use of computer modelling to identify the optimal characteristics and geographical distribution of perennial grasses for biomass production
• pre-breeding of novel varieties
• investigation of stress tolerance
• investigation of post-harvest drying characteristics.
The GrassMargins project is funded under the co-operation scheme of the 7th EU framework programme and has partners from a range of disciplines (modelling, agronomy, ecophysiology, genetics, geography and dissemination specialists) from eight countries (Ireland, UK, Denmark, Sweden, China, Russia, Poland and Germany).
Modelling and mapping biomass production
Computer modelling is being used to predict biomass production from perennial C3 and C4 grasses under different growth conditions. Current work focuses on the production of a new process-based perennial grass crop production model.
A “Review of optimal morphological and physiological traits and management practices to gain higher biomass production in perennial rhizomatous grasses” has
been produced and submitted for peer review.
The occurrence of the grasses Dactylis glomerata, Festuca arundinacea and Phalaris arundinacea is being mapped across Europe and will be incorporated into
a high resolution Geographical Information System within Grassportal.org. Climate envelope modelling, which is based on the determination species’ tolerance, is being used to predict the full geographical range of C3 and C4 perennial grasses.
Within the project, new genotypes of the project grass species are collected from a range of habitats and novel Miscanthus hybrids are generated by crossing existing genotypes. Genotypes for crosses were selected from existing Miscanthus spp. genotype collections from GrassMargins partners.
To date 42 crosses have been made between Miscanthus sinensis and four crosses between Miscanthus sinensis and a Miscanthus sacchariﬂ orus accession from Russia.
From these crosses, 14,588 propagated plants were planted at partner locations in trials in early summer 2012. Collections of Phalaris arundinacea and Dactylis were made in the UK and Ireland in 2012 and in Poland, Germany, Denmark and Sweden in 2013. The development of novel molecular markers and next generation sequencing genotyping of the project species is under way.
Stress screening of the abiotic stress factors affecting biomass production in the partner countries of the project are being investigated. A salt screening test of around 140 entries showed that Festuca had the best tolerance to elevated levels of sodium in the soil, while Phalaris was most affected by sodium and showed significant
growth reduction under low salt stress.
Extensive measurements on Miscanthus cold tolerance were done using several hundred genotypes. Measurements of leaf growth, photo synthesis, visible frost damage and content of pigments and photosynthetic enzymes were used to differentiate between genotypes.
A large genotypic variation in cold and frost tolerance was observed, and the most tolerant genotypes have been selected for detailed investigation in climate chambers during 2013. For the environmental stresses, RNA sequencing work has commenced to identify transcripts involved in the regulation of those stress
conditions for the four species investigated in this project.
The next step was to quantify the biomass production of perennial grass species on marginal land, in order to see if economical yields of biomass can be obtained. The biomass of perennial grass species on marginal land is being quantified in order to see which genotypes/species are best suited for marginal land. These trials are managed according to an annual multi-cut harvest system, which would supply biomass to an anaerobic digestor or bio-refinery.
Four Miscanthus genotype trials have been established on different types of marginal land in Ireland in order to identify, which grow well. These trials will be harvested annually in spring, as Miscanthus is typically cultivated as a feedstock for combustion.
Impact of the GrassMargins project
The research will provide information vital to the realisation of a previously untapped bioenergy resource, that of grass production on marginal lands. This information includes a range of genetic resources on grass species (Miscanthus, Phalaris, Festuca and Dactylis), which are potentially suitable as biomass feedstock.
It will identify the genes responsible for traits that are desirable in biomass species and develop models of the physiological and micrometeorological processes affecting their performance in different habitats.
Furthermore, it will assess the extent to which selective breeding may generate desired improvements in the traits that determine their suitability as biomass species.
Partners have been chosen for their expertise and knowledge of grasses in a wide range of marginal habitats worldwide.
The consortium will also assess the suitability of collected species for cultivation in different types of marginal lands challenged by extremes of salt, fl ooding, drought and cold. Finally, GrassMargins will study some of the factors that are believed to affect biomass production on marginal lands, including the relative merits of grass
mixtures versus mono-species, and the factors affecting plant moisture levels.
The project will produce a significant database of geographically referenced information on the grass species of relevance to the project for biomass production. This data will be available for both the scientific community and the general public to help build an understanding of the propensity of grass species for improved biomass production on currently under-used marginal land.
The ultimate goal of this data is to make a significant agricultural impact in the EU by informing companies and institutions interested in growing, breeding and propagating grass species that are strongly resilient in the presence of abiotic stresses. Secondly, the results will inform the general public on the challenges relevant to the development of a sustainable biomass crop production strategy.
No conflict with land for food
Bioenergy produced from marginal lands can be exploited without undue conflict with food production. The identification of additional bioenergy resources will become increasingly important as fossil fuel prices continue to rise but also as the 2020 targets for renewable energy production are approached.
Meeting these targets, established in the renewable energy directive (2008/28/ec) for each EU Member State, will require the identification of additional renewable energy resources as the 2020 target date approaches.
As such, this proposed research is timely as it will facilitate the exploitation of this important renewable energy resource and the availability of results will coincide with demand for additional resources.
The GrassMargins project will contribute scientific proceedings to the 2014 Dublin Federation of European Societies of Plant Biology meeting in its plant biology for bioenergy session which is set for June 22-26 next year at the Dublin Convention Centre.
By Dr Susanne Barth, research officer; Dr Manfred Klaas, research officer; Brendan Burke, research technician; Deirdre Doyle, research technician; Dr John Finnan, research officer; Teagasc, Crops, Environment and Land Use Programme, Oak Park Research Centre, Carlow.
This feature first appeared in Teagasc’s TResearch publication, which is available here.