Climate change: A predicament of food crops
May 28th, 2014 | Aleena Mushtaq | No Comments
The constant threat of global climate change has not only affected human life but also it has proved to be a menace for the biodiversity functions, ecosystem, and social structure plant diseases. Numerous impacts and studies have been reported about the abiotic constraints, which have intensively influenced the flora and fauna. Especially, in the case of food crop diseases and food security, the whole world is now finding ways to combat this challenge. To face this predicament of global climate change there is need to utilize the integrated, multidimensional, and multi-scale effort so that a comprehensive, efficient, effective and practical solution can be chalked out to save the crops from various emerging pathogens and races which are reducing losses in overall productivity and a threat to food security.
Due to this reason sowing and harvesting dates are changing day by day. Owing to this fact, wheat did not reach at its maturity and full grain size is not attained in such a short period. This leads to the reduction of yield. Especially, Pakistan is facing worst effects of climate change as it ranked at fourteenth position in the most affected countries of world with respect to climate change in the form of fluctuations in seasons, floods and destruction of crops.
Adding fuel to the fire, the quality of food is deteriorated which resulted in evolution of such issues like malnutrition, undernourished and food safety. Another major issue which came into being due to climate change is high level of desertification and soil salinization in some regions of Pakistan.
Similarly, the growing level of CO2 associated with climate change may affect the distribution, abundance and performance of plant pathogens. Increased CO2 may modify pathogen aggressiveness and host susceptibility by affecting the initial establishment of the pathogen on the host. The increased productiveness and growth of some fungal pathogens under elevated CO2 is also reported, together with, an increase in plant canopy size (especially in combination with humidity), and an increase in host abundance and biomass can increase the size of pathogen populations.
Among cereal crops, wheat is the most important one. It is consumed as a staple food for many countries including Pakistan. The production of wheat rice and maize is reduced 20 per cent, 15 per cent and 9 per cent respectively due to change in climate. The temperature of the earth has increased to about +5 per cent. For instance wheat stripe rust (Pucciniastriiformisf.sp. tritici) is serious pathogens of wheat all around the world. Moisture, temperature and wind are the three most important weather factors affecting epidemics of rusts. Increasing global temperatures may limit the development and survival of rusts in some wheat growing regions around the world.
In case of rice, temperature change emerged as the main determinant of crop loss. An experiment named rice free air CO2 enrichment experiment was conducted in which rice plants were grown under elevated CO2 to primarily assess yield effects under future climates. The first pathogen assessed was M. oryzae (Causal Organism of Rice Blast). Rice blast (Magnaporthegrisea⁄oryzae complex) and sheath blight (Rhizoctoniasolani) causes crop losses annually worldwide.
A rich source of carbohydrates and staple crop of many regions of the world, Potatoes are important for the diets and livelihoods of millions of people worldwide. Global potato production has grown markedly in the past years and in 2005. Without adaptation measures, it is predicted that potato yield will decrease by 18-32 per cent with climate change. On the contrary, the recent quantification of disease incidence during this period has demonstrated increase in level of diseases which are correlated with climate change. Common scab was considered to be most prevalent due to this change in climate amongthe other three most important and common bacterial diseases of potatoes like Black leg and Brown rot.
Due to the rise in temperature, crops are developing more rapidly and mature earlier as there is fluctuation in the temperature. For example, citrus, grapes, melons etc. continue to mature earlier by about 15 days and more vegetative growth in these crops can be seen hence, there reproductive period will be shorten. It is a matter of shortening of fruit growth and production period, which is a direct impact of climate change on the part of rising food insecurity in world. There is delay in monsoon, dry seasons leading to untimely rains during water stress period. Similarly, hailstorms are some of the most commonly encountered climatic conditions experienced by the citrus growers recently. Furthermore, sunburn and cracking in apples, apricot and cherries has been increased due to climate change and temperature at maturity.
It can be concluded from the facts that more research on the impact of climate change is needed as all the above described research is insufficient to overcome the impact of climate on plants diseases and host, disease environment relationship. Climate change affect plant health, but a regionally-to globally, declining plant health may in turn accelerate climate change because of the additional carbon emissions due to increased plant mortality and soil organic matter mineralization, so that plant disease management, by maintaining plant health, has a role in reducing and preventing greenhouse gas. The ability to generate genetic variations as a response to changes in the environment enables plant pathogens to become highly adaptive organisms. New phenotypic strains or pathogenic races often arise in response to changing climate or the deployment of resistant host cultivars, such as with wheat rusts. Therefore, it will be important to consider pathogen evolution and the effectiveness of resistant plant varieties for an accurate assessment of diseases on food crops in the future.
The writer is associated with the Department of Plant Pathology, University of Agriculture Faisalabad, Pakistan.
Published in: Volume 05 Issue 22
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