Rising temperatures reduce global wheat production
Crop models are essential tools for assessing the threat of climate change to local and global food production1. Present models used to predict wheat grain yield are highly uncertain when simulating how crops respond to temperature2. Here we systematically tested 30 different wheat crop models of the Agricultural Model Intercomparison and Improvement Project against field experiments in which growing season mean temperatures ranged from 15 °C to 32 °C, including experiments with artificial heating. Many models simulated yields well, but were less accurate at higher temperatures. The model ensemble median was consistently more accurate in simulating the crop temperature response than any single model, regardless of the input information used. Extrapolating the model ensemble temperature response indicates that warming is already slowing yield gains at a majority of wheat-growing locations. Global wheat production is estimated to fall by 6% for each °C of further temperature increase and become more variable over space and time. [1]
Challenges to wheat production in South Asia
Wheat is the second major staple crop, after rice, in India and Pakistan and is also gaining similar importance in Nepal and Bangladesh. Wheat production in South Asia has increased from 15 mt in 1960s to 95.5 mt during 2004–2005. It still needs to grow at the rate of 2–2.5% annually until the middle of 21st century. However, for India, recent estimations have shown a growth requirement of about 1.1%. Although the wheat improvement programs in these countries, with the active collaboration of national agricultural research centers (NARS) and CIMMYT, has made a significant progress, it is a matter of significant concern that wheat production has stagnated for last few years. Since there is little scope for increasing land area under wheat, the major challenge will be to break the yield barrier by pragmatic genetic and developmental approaches. The most serious constraints to wheat production in this region are a host of biotic and abiotic stresses. Although India has not faced any rust epidemic in the last decade, rusts continue to occupy the place of most dangerous pathogen for the region. Among the abiotic stresses, unusual warming trends during grain filling period are causing yield declines, especially in eastern and central India. There are other challenges that are specific to the highly productive rice–wheat cropping system predominant in the Indo-Gangetic plains. The total factor productivity of this system is declining due to depletion of soil organic carbon. Addition of organic matter to soil through green manuring and crop residue recycling, balanced fertilization, integrated nutrient management, diversification of rice-wheat system are some of the possible remedial measures to improve total factor productivity. The international linkages with CIMMYT needs to be strengthened more closely for developing more productive wheat genotypes and thus, achieving wheat targets in the South Asian region.[2]
Reducing the reliance on nitrogen fertilizer for wheat production
All crops require nitrogen (N) for the production of a photosynthetically active canopy, whose functionality will strongly influence yield. Cereal crops also require N for storage proteins in the grain, an important quality attribute. Optimal efficiency is achieved by the controlled remobilization of canopy-N to the developing grain during crop maturation. Whilst N will always be required for crop production, targeting efficient capture and use will optimise consumption of this valuable macronutrient. Efficient management of N through agronomic practice and use of appropriate germplasm are essential for sustainability of agricultural production. Both the economic demands of agriculture and the need to avoid negative environmental impacts of N-pollutants, such as nitrate in water courses or release of N-containing greenhouse gases, are important drivers to seek the most efficient use of this critical agronomic input. New cultivars optimised for traits relating to N-use efficiency rather than yield alone will be required. Targets for genetic improvement involve maximising capture, partitioning and remobilization in the canopy and to the grain, and yield per se. Whilst there is existing genetic diversity amongst modern cultivars, substantial improvements may require exploitation of a wider germplasm pool, utilizing land races and ancestral germplasm. [3]
Impact of Climate Change on Wheat Production in Nepal
Following the Ricardian approach, this paper estimates district level fixed effect panel regression on per hectare net wheat revenues with climate variables like precipitation and temperature including other traditional inputs. Both temperature and precipitation coefficients reveal that the climate change caused negative impact on net wheat revenues from wheat production but in a decreasing rate, ceteris paribus. The joint effect of the temperature and precipitation is also significantly negative. Quite trivial that other traditional inputs like population density, manure used, human labour, wages, advanced seed and fertilizer used are positively associated with net revenues. However, per hectare bullock used and tractor price are negatively associated to net revenue. The negative sign reported for the coefficients of quadratic proxy climate change variables but positive for their level form indicate that rising temperature and precipitation initially encourage wheat production in Nepal, but after certain threshold level it start hampering the yield.[4]
Impact of Education and Certified Seeds on Wheat Production in Kohat, Pakistan
The study was conducted to investigate the impact of education and certified seed on wheat production in district Kohat, Pakistan. For the purpose, proportional allocation sampling technique was used and total of 100 respondents randomly selected to get necessary information. Simple budgeting technique was used for cost and return of wheat production. The econometric technique, Ordinary Least Squares (OLS) OLS estimation model was used to analyze contribution of major factors in the wheat yield. The sign of explanatory variables were found according to our prior expectation of the economic theory. The estimated results of production function indicated that farm yard manure(FYM), total fertilizer nutrient applied and labor days had positive and significantly effect on wheat yield, seed rate had positive but insignificant effect on wheat yield. The impact of both Dummy variables i.e. education and certified seed was positive and significantly affect wheat yield. Finally, it was suggested that there is the need for strengthening agricultural extension services in the study area in order to educate the farming community to ensure the use of recommended certified seed and modern agriculture technology for getting high yield of wheat crop.[5]Reference
[1] Asseng, S., Ewert, F., Martre, P., Rötter, R.P., Lobell, D.B., Cammarano, D., Kimball, B.A., Ottman, M.J., Wall, G.W., White, J.W. and Reynolds, M.P., 2015. Rising temperatures reduce global wheat production. Nature climate change, 5(2), pp.143-147.
[2] Chatrath, R., Mishra, B., Ferrara, G.O., Singh, S.K. and Joshi, A.K., 2007. Challenges to wheat production in South Asia. Euphytica, 157(3), pp.447-456.
[3] Hawkesford, M.J., 2014. Reducing the reliance on nitrogen fertilizer for wheat production. Journal of cereal science, 59(3), pp.276-283.
[4] Thapa-Parajuli, R.B. and Devkota, N., 2016. Impact of climate change on wheat production in Nepal. Asian Journal of Agricultural Extension, Economics & Sociology, pp.1-14.
[5] Ullah, A., Shah, S.N.M., Shaofeng, Z., Khan, M. and Ali, S., 2015. Impact of education and certified seeds on wheat production in Kohat, Pakistan. Asian Journal of Agricultural Extension, Economics & Sociology, pp.42-48.