Wheat is the world’s third most important cereal crop, after maize and rice. Globally, it occupies 222 million ha areas across all major regions of the world and produces 729 million tonnes (MT) grains. India contributes 13 per cent to the global wheat production of 729, with 94.5 MT grown on 31.2 million ha areas (fao.org).
Since 1961, there has been an annual growth rate of 4.19 per cent, with a 1.5 per cent annual horizontal expansion in area and 2.64 per cent vertical expansion in yield. However, despite an augmented availability of critical inputs, there is a significant average decline in annual wheat production over the last two decades (Fig. 1). A closer examination of the weather data indicates that the declining trend in yield may be attributed to climate variability and climate change (Kumar et al., 2012).
Recent climate change trends
Climate change and variability are emerging as major challenges for the Indian agricultural sector. The high inter and intra-seasonal variability in rainfall distribution, rainfall events and extreme temperatures are causing crop damages and losses to farmers. Studies pertaining to India show enough evidence of rising mean temperatures during the post-1970 period. A warming of 0.21°C per 10 years during the post-1970 period as compared to 0.51°C rise per 100 years during the past century has been reported. In many parts of India, the frequency of occurrence of cold nights has declined, while the frequency of warm nights and warm days has significantly increased. Besides, the country experienced 15 deficit and 6 excess monsoon years in the post-1960 period in comparison to only 27 deficit and 20 excess monsoon years during 1871-2014. The pattern of climate change has already begun affecting Indian agriculture adversely through enhanced abiotic and biotic stresses on crops and livestock.
Various climate models indicate a consistent warming trend over India in short, mid as well as long-term scenarios (Chaturvedi et al., 2012). In comparison to the 1960-90 baseline period, the mean annual temperature over India is projected to increase 1.7-2.0°C by 2030s, 2.5-3.0°C by 2050s and 4.0-5.0°C by 2080s. Similarly, a substantial increase of 6-14 per cent in extreme precipitation by 2080s is projected for large areas of India, particularly over the west coast and west central India (Rupa Kumar et al., 2006). In addition, droughts and floods as well as cold and heat waves are likely to increase due to the rise in temperature which may cause up to 30 per cent crop losses by the 2080s (Singh, 2010).
Impact of climate change on Wheat Production
Wheat is already facing the negative impacts of climate change in many parts of the country due to rising temperatures, water stress, reduction in rainy days and increased incidence of disease and pest attacks. The rise in temperature, though, is bound to be a major denominator as almost 93 per cent of the area under wheat is irrigated. In Haryana, night temperatures during February-March, 2004 were recorded to be 3°C above normal. This saw a decline in wheat productivity from 4106 kg/ha to 3937 kg/ha during this period (Ranuzzi & Srivastava, 2012).
In general, climate change enhances variability in abiotic and biotic stresses which influence germination, growth, reproduction, pollination, fertilisation and maturity processes of crops, crop duration, and, incidence of diseases and pests. Consequently, crop productivity and quality, crop diversity, and input efficiency is affected. Further, change in rainfall intensity and pattern can affect water availability and water demand, and hence cause a proliferation of new and existing pests.
The optimal growth conditions for spring wheat are achieved when temperatures range between 12 and 23°C. In India, this situation usually begins in November/December, with the growing season ending by March/April when there is a gradual rise in temperature. The crop needs sufficiently prolonged cool period to promote tillering and flowering. Any departure from the optimal range causes some level of stress, decline in yield attributes and hence loss of yield. Temperatures greater than 34°C significantly accelerate the senescence of leaves, while a temperature of 40°C is considered to be the critical threshold level.
If a maximum temperature above 47.5°C occurs, it is lethal for the crop, and can cause immediate drying or maturing (Koehler et al., 2013). Further, high temperatures combined with high air humidity encourage disease and pest incidence especially rust problems.
Several studies have been carried out to quantify the impacts of climate change on Indian agriculture, and particularly wheat (Kumar, 2011). Although there are variations across the models for the magnitude of the impact, all models predict similar changes.
Recently, the Infocrop-Wheat model projected an overall yield reduction of 6 to 23 per cent by the 2050s and 15 to 25 per cent by the 2080s. A higher reduction in yield is projected for warmer central and southern regions (Kumar et al., 2014). Thus, the major predictions for the wheat scenario in the country include:
- Higher temperature ranges in future with increased number of heat events (likely to double in the next 50 years),
- Disruption in sowing due to high temperatures during sowing period,
- Possibilities of losses upto 4-6 MT in wheat production in future with every 1oC rise in temperature throughout the growing period,
- Substantial loss of suitable production environment due to overall increase in temperature,
- Increase in CO2 to 550 ppm may augment yields of wheat by 10-20 per cent,
- Significant impacts on quality of wheat grain
- Increased frequency of droughts and floods likely to increase production variability, and
- Considerable threats of pathogens and insects.
Coping with weather aberrations
Studies showed that simple and low cost adaptation options, such as improvement in sowing time, increased and efficient use of inputs, and crop management practises could not only reverse reduction in yield, but also improved yields until the middle of the century (Fig. 2)
With increase in temperature many physiological and biological activities get restricted which results in lower fertiliser uptake and photosynthesis. Further, many soil microbial and chemical processes also discourage uptake of sufficient nutrients. Overall the net availability of fertiliser to plants gets restricted. Therefore, enhancing fertiliser dose could compensate the loss in yield due to climate change.
These mitigation strategies entail the changing of the micro-climate for the crop production. Using this, a marginal gain in wheat by 2050 is reasonable. But, by 2080, the further rising of temperature will again shorten the growing season beyond a critical threshold duration required for sufficient growth in vegetative and reproductive stages. Thus, despite advanced technologies, the shortened crop duration and higher temperature might cause lower yields.
Field and simulation studies have shown that the impact of climate change could effectively be offset through adoption of various adaptation measures. The short term adaptation options include preparing farmers for coping with climate change, adoption of improved crop varieties and smart farming practices, adoption of efficient water and nutrient management measures and improved flow of information to farmers. Medium term options include breeding varieties for better resistance to heat and biotic stresses, high water and nutrient use efficiencies and ability to take advantage of elevated CO2; adoption of improved conservation technologies, crop diversification, and enabling economic and policy environment.
Smart practices and technologies
Over the years, arrays of practices and technologies have been developed to manage the seasonal variations, and adoption of such resilient practices and technologies by farmers now appears to be more of a necessity than an option. Therefore, Indian Council of Agricultural Research (ICAR) took a major initiative to strengthen and converge the random efforts of institutes through launching of National Innovation on Climate Resilient Agriculture (NICRA) in 2010-11. Since then, the project has identified several smart practices and technologies that could help wheat farmers to cope with climate variability. These include: (i) short duration and heat tolerant varieties, (ii) recharge of shallow aquifers, (iii) rainwater harvesting and recycling through check dam, jalkunds and farm ponds, (iv) improvement in conveyance efficiency and adoption of micro-irrigation techniques, (v) improved planting methods, (vi) adoption of integrated nutrient management practices, (vii) adoption of conservation agriculture based integrated crop management practices including zero-till drill wheat, (viii) adoption of resource conservation techniques viz. laser leveling and broad bed-furrow (BBF) planting, (ix) surface mulching and in situ incorporation of biomass and crop residues, (x) building village level seed banks, (xi) integrated farming system modules, (xii) custom hiring centers for farm machinery, and (xiii) crop diversification.
The climate change scenario has made a paradigm shift in farming objectives from enhancing productivity to sustaining production. This requires a change in the mindset and capacity building of farmers. Our experiences through the technology dissemination component of NICRA has demonstrated that this could be achieved through participatory R&D processes, promoting adaptive research and field demonstrations, trainings and capacity building of farmers and extension workers, and strengthening farmer-extension worker-scientist linkages (Prasad et al., 2015) through farmer’s field schools.
Dissemination of information
Timely information is a critical tool to act against the vagaries of climate. It needs strengthening of infrastructure to transmit the information on real time basis. Concerted efforts are also required to generate and timely disseminate medium and short term forecasts and newscasts with associated risk management practices, market information and contingent plans for extreme weather events. ICAR has already developed and demonstrated dynamic contingency plans and general crop advisories to tackle possible weather eventualities for 600 districts.
Climate resilient crop varieties
Climate resilient crop varieties play a crucial role in coping with climate variability in agriculture. The ICAR institutes and state agricultural universities (SAUs) are making concerted efforts to develop high yielding wheat cultivars with enhanced tolerance to delayed monsoon and drought situations (Table 1).
Economic and Policy Issues
A clear and long-term policy support is required to enhance sustainability in wheat production and food security of the country. Strategies for water and nutrient management support to R&D towards climate change, and management of risk and uncertainties in wheat production are to be assigned higher priority. The policies on water management should incentivise its conservation and efficient use, while policies on nutrient management need to promote integrated nutrient management practices, fertigation and crop residues recycling. Besides this, high priority should be placed on R&D efforts to breed multiple stress tolerant varieties, production of enough quality seeds, developing and up-scaling appropriate agronomic practices, and innovative extension policies. Newly launched, January 13, 2016, scheme of Pradhan Mantri Fasal Beema Yojana (PMFBY) has already broadened the scope of safety net and addresses issues pertaining to climate change.
Climate change has emerged as a major challenge to agriculture, and the ICAR has initiated NICRA project with the three components of strategic research, technology demonstration and capacity building to enhance its resilience. Besides this, ICAR is already working to strengthen interaction between agricultural scientists and farmers, and better convergence between research and development needs. The Indian government is also addressing the issues of climate change through National Mission on Sustainable Agriculture (NMSA launched in 2011-12) as programmatic intervention to infuse the judicious use of resources especially through community based approach. Besides, climate resilient interventions have been embedded and mainstreamed into missions/programmes/schemes of Department of Agriculture & Farmers Welfare (DAC & FW) through a process of restructuring and convergence.
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