Marginal lands are often defined as areas that are unable to support permanent or intensive agriculture without significant investment in land or water management. Exploring these types of lands to cultivate biomass crops is of particular interest to society to avoid creating a competition environment between bioenergy crops and food crops. In order to create resilient production systems that can tolerate the increased climatic variation foreseen with climate change in such pieces of land, it is important to increase the stress tolerance of the target perennial grasses being studied in GrassMargins. Important stress factors that we have selected to address are drought, salt, flooding and cold.
Abiotic stress is caused in plants by environmental conditions which expose the plants to drought, flooding, extreme temperatures and poor soil conditions including nutrient deficiency (Larcher, 2003). Exposure to abiotic stress conditions has negative impacts on crop performance, yield and sustainability. Optimising the crop yield for the type of land it is planted on is a critical requirement to the successful use of marginal lands for the production of biofuels. Multiple abiotic stresses are characteristic of marginal areas and in order to create resilient production systems, it is important to increase the stress tolerance of perennial grasses. Furthermore, it will become increasingly important to identify varieties that can tolerate the increased climatic variation foreseen with climate change.
The cool-temperate climatic zone of Eurasia and North America represents a vast area that could potentially be cultivated to meet a future demand for productive bioenergy crops. One of the main challenges faced by high yielding grass species in this zone is that the cold climate has a tendency to reduce the photosynthetic performance and therefore plant growth in comparison to other plant species in the same zone.
There are, however, a few tens of potentially high yielding grass species from the Miscanthus genus that are tolerant to low temperatures which will be studied during throughout the course of this project.
Grasses which usually grow on wetlands (e.g. Phalaris arundinacea) do not have well developed water saving mechanisms and have low water use efficiency, however they are likely to possess important water-logging tolerance characteristics (Mueller et al., 2005). Root aerenchyma, or root airspace, is an important trait of plants that thrive under flooded conditions, and P. arundinacea had the highest levels of root airspace of 17 wetland species investigated (Kercher & Zedler, 2004). Understanding the ability of certain grass species have to adapt to temporary flooding is very important for future breeding of bioenergy grasses.
Drought stress is a very common production constraint in agriculture in general, and may become increasingly so in the warming climate, where longer dry spells are envisaged even if annual precipitation remains unchanged. Also, the use of marginal land for bioenergy production often implies lower water holding capacity of the soil or lower precipitation than of the land in intensive use for food production. Many reports have shown differences between species and ecotypes in drought resistance (Clifton-Brown et al., 2002; Reed et al., 2008; Weng 1993).
Salt stress is today in Europe mainly a problem in southern and south-eastern conditions (Spain, Romania and Hungary) (Tóth et al., 2008), but the areas may increase with climate change. Natural genetic selection for salt tolerance in Phalaris arundinacea has been described within a community of mixed grasses subjected to salt stress over a more than 20 year period (Maeda et al., 2006), showing that selection and breeding can be an efficient tool.