Responses of Cereal Plants to Environmental and Climate Changes – A Review

Abstract

The projections of the global climate changes on the Earth expect a rise in the concentration of greenhouse gases, increase in temperature and aridisation of the environment. By the middle of the twenty-first century, the concentration of CO2 will probably rise up to 500 μl l−1 of air. Already now, 61% of the area of land on the Earth has precipitation lower than 500 mm. One-sixth of the world’s population can be affected by an acute shortage of water. A total of 35–50% of inhabitants of the Earth are struggling with salinity of soil. All this currently has and will have consequences for the agricultural production. The areas between 15° and 30° of the north and south longitude and the deep inland areas are endangered the most. Cereals are major crops with respect to human nutrition. In order to ensure permanently sustainable production of cereals, it is important to study the diversity of their production under the influence of natural and climate changes. Based on this analysis, it is necessary to design measures to stabilise yields. This is the purpose of this chapter. Based on the study of a number of literature sources, we presume that the increased concentration of CO2 will only partly compensate for the losses of the yields of cereals resulting from the increase in temperature and aridisation of the environment taking place on a global scale. However, cereals have a number of adaptation mechanisms to maintain turgor and to improve water management in dry and salinised habitats. With a view of ensuring permanent sustainability of agricultural production under the changing natural and climatic conditions, we present two options of using the diversity of adaptation mechanisms: (1) to adapt the composition of the cereals grown to changing conditions; (2) to breed varieties more resistant to changing conditions. Breeding resistant genotypes is the least costly solution to ensure sustainable development of agriculture in arid areas. We believe that the choice of suitable selection criteria is most important. For the screening of genotypes resistant to drought and salinisation, it is important to use more parameters: physiological and biochemical indicators at the cellular level and the genes of resistance to drought and salinisation. The suitable selection criteria and the important features of drought and salinisation resistance are a high level of osmotic adjustment, low stomatal conductivity and good growth of roots. Breeding aimed at achieving a higher degree of drought resistance should be focused on (1) improvement of the availability of water through the root system; (2) the limitation of water loss through transpiration and higher water use efficiency for production of biomass; (3) prolongation of the activity and increase of the power of the sink. In the selection of the genetic sources of resistance to abiotic stresses, we recommend paying an even greater attention to wild species and region-specific and primitive varieties of cereals, originating from worse natural and climatic areas. Another promising path is to use gene transfers to improve the photosynthetic and growth capacity of cereals during the presence of stress factors. In order to improve the water management in cereals under dry conditions, we also suggest using growth regulators to a greater extent. Abscisic acid applied on plants can serve as an antitranspirant. It can increase water use efficiency.