1 Introduction

Evolution has been the basis of species development. On the earth, about 1 million plant species exist, of which around 350,000 are accepted, while more than 240,000 are yet be resolved into ‘accepted name’ or ‘synonym’ (BGCI 2017). Out of these, only about 20,000 species are edible. Ever since settled agriculture was invented by human being over 10,000 years ago, numbers of species that are cultivated have been shrinking. Increase in population and demand for higher production of food grains led to expansion of area under agriculture on one hand while narrowing down the number of species to only a few on the other. Intensification of agriculture led to a further narrowing down of species that are being cultivated. Currently, only 20 species are providing over 90% of our food. Even among these, only a few varieties or hybrids are being cultivated causing extreme narrowing of gene pool in agroecosystems . Among the major species that are cultivated, probably rice is the only crop with larger diversity. Major cultivated crops have been subjected to improvement though human intervened conventional breeding or molecular breeding .

Natural selection has been the driving force for evolution of biological organisms on the earth. Organisms that could keep the pace of their evolution way ahead of the changing climatic conditions can dominate the ecosystems. Organisms that evolve at the pace of changing climates may sustain their existence till the time when the pace of climate change overtakes the pace of their evolution and eventually extinct. Other organisms which cannot keep the pace of evolution as that of the climate change will extinct. This basic principle is applicable to all organisms and cultivated species are no exception.

Climate, the mean state of weather over a long period (usually 30 years), of the earth has been dynamic and has been changing continuously. Out of 4.54 billion years of the earth’s age, 3 million years has seen glacial and interglacial cycles. Last interglacial period occurred about 125,000 years ago. During this period the global mean surface temperatures were 1–2 °C warmer than present 15 °C. During the last glacial maximum, where the ice covered the earth’s surface to the maximum extent about 21,000 years ago, the global mean surface temperatures were 4–7 °C cooler than present. The greenhouse gases (GHGs) are responsible for tapping of energy by the earth’s atmosphere. Without GHGs, earth’s surface mean annual temperature would have been −17 °C making earth unsuitable for living organisms. The presence of GHGs in the atmosphere and greenhouse effect causes warming of about 32 °C. This resulted in a global mean annual temperature of +14.84 °C in 2016 (NOAA 2017).

Human activities such as fossil fuel combustion and the GHG-emitting man-made technologies, on the one hand, and deforestation and land use change, on the other hand, have led to rapid accumulation of GHGs. All these GHGs have differential potential to warm the earth’s surface, called global warming potential (GWP) . The GWP is the measure of how much heat a greenhouse gas traps in the atmosphere relative to the amount of heat trapped by carbon dioxide. Carbon dioxide (CO2) , by definition, has a GWP of 1 regardless of the time period used, because it is the gas being used as the reference. The GWP of methane is 21 times and N2O is 310 times of GWP of CO2 in a 100-year period. The GWP of sulphur hexafluoride (SF6) (23,900), hydrofluorocarbons (HFCs, vary between 140 and 11,700 times depending the type of molecule) and perfluorocarbons (PFCs) (6500–9200) is extremely high for 100-year period. Collectively, their GWP is leading to increase in temperatures and climate change.

Climate change is projected to raise the global surface temperature in excess of 1.5 °C by 2100 relative to 1850–1900, and warming will continue beyond 2100 (IPCC AR-5 2013:2014). Increase of global mean surface temperatures for 2081–2100 relative to 1986–2005 is projected to be 0.3 °C to 1.7 °C in GHG mitigation scenario (representative concentration pathway, RCP2.6); between 1.1 °C and 2.6 °C (RCP4.5) and 1.4 °C to 3.1 °C (RCP6.0) in GHG stabilization scenarios and by 2.6 °C to 4.8 °C (RCP8.5) in GHG emission intensive scenario. Concurrently the atmospheric CO2 concentrations are projected to increase to 421 ppm (RCP2.6), 538 ppm (RCP4.5), 670 ppm (RCP6.0) and 936 ppm (RCP 8.5) by the year 2100. Further, climate change is projected to increase frequency of extreme temperature events, extreme rainfall events and skewed monsoon leading to increased risk of drought-related water and food shortage. Further, the report suggests that the risk level can be moderately minimized with current adaptation and risk level with high/intensive adaptation can be minimized.

Climate change impacts on crops are projected to vary with the type of species, location and season of crop growth. Several studies have projected that global production of many crops may reduce to the tune of 40–60% due to rise in temperature and climate change by the end of the century (Rosenzweig et al. 2014). The magnitude and direction of climate change impacts have significant spatio-temporal variation for a given crop, with some regions gaining yield while other losing it based on the current climatic conditions (Naresh Kumar et al. 2011, 2013). However, adaptation to climate change will not only reduce the negative impacts but also maximize the positive effects. Adaptation of agriculture to climate change involves managing current and future climatic risks . This can be achieved through an integrated approach of (1) anticipatory research efforts, (2) management of natural resources, (3) use of technology and (4) proactive development and policy initiatives. Several low-cost technologies can reduce the negative impacts of climate change (Easterling et al. 2007). Among the natural resources, genetic resource is the major factor that determines the performance of agricultural productivity. Growing suitable crop variety in changing climates is identified as one of the essential and easy-to-adapt strategy for not only minimizing the negative impacts but also for harnessing the beneficial effects (Braun et al. 1996; Chapman et al. 2012).

Historically, crop improvement has been aimed to achieve high yield, resistance to disease and pest and tolerance to abiotic stresses. Screening germplasm for identification of donors having specific traits and their utilization in developing resistant and tolerant varieties has been the convention in crop improvement (Ortiz 2002; Xin-Guang et al. 2010b). Breeders have been successful in achieving their targets. However, changing climates have been throwing new challenges for crop improvement.

2 Why Genetic Adaptation in Changing Climates?

The centre of origin of many crops falls in the region between Tropic of Cancer and Capricorn. Climate change has been changing the climatic conditions of these regions at a much faster pace resulting in new or novel climates (Williams et al. 2007). Since climate is the primary factor for species distributions and ecosystem processes, the new climates may pose challenge to the existing species, while new species may emerge. Novel climates are projected to develop primarily in the tropics and subtropics, challenging large portion of existent biodiversity to evolve faster. Species that evolve faster can survive, while those who are slow will eventually become extinct . This calls for an immediate action of conservation of all biodiversity in these areas, in general and in biodiversity hotspots, in particular. It is quite probable that lack of such efforts had led to the collapse of civilizations due to the late Holocene droughts between 6000 and 1000 years ago. Droughts resulted in the collapse of empires and societies like the Akkadian Empire of Mesopotamia, c. 6200 years ago; the Classic Maya of Yucatan Peninsula, c. 1400 years ago (Ceccarelli et al. 2010); the Moche IV–V transformation of coastal Peru, c. 1700 years ago (de Menocal 2001); and the early bronze society in the southern part of the Fertile Crescent (Rosen 1990), to name a few. Not just of historical events, these examples have current relevance as well, particularly in the current world where the food habits of regions are gradually merging.

Crop species gene pools are collected, conserved, catalogued and characterized for the use in crop breeding. As mentioned earlier, most of the genetic enhancements are made to achieve higher yield, resistance to specific disease and pest and tolerance to some abiotic stresses. Efforts to increase quality also have led to nutritionally enhanced varieties. While all these were done with focussed screening of germplasm to identify lines with ‘desirable’ traits, they ignored or overlooked to analyse its performance with climatic variability as the backdrop. Therefore, there is a need to contextualize the breeding efforts in changing climates to improve the crop yields as they are projected to reduce in the changing climates.

Climate change is projected to affect the yield of several major crops across the world. For instance, the global yield of maize, wheat, rice and soybean is projected to be affected up to 20% in 2020 (2010–2039) scenario, 20–35% in 2050 (2040–2069) and 40–60% in 2090 (2070–2099) (Rosenzweig et al. 2014). A global analysis on wheat production indicated a decrease of about 6% yield with every 1 °C rise in temperature (Asseng et al. 2015). The impacts are variable over space and time, e.g. more effects would be visualized in tropical regions (IPCC 2014). The projected climate change events and major impacts on crop productivity in different continents (Table 12.1) indicate a need for concerted effort to adapt to climate change. The IPCC reported that each additional decade of climate change is expected to reduce mean yields by roughly 1%, while the anticipated increase in productivity per decade needed to keep pace with demand is roughly 14% (IPCC 2014).

Table 12.1 Major climate-related risks and projected impacts on agricultural systems in different continents
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In Indian region, areas encompassed by climatic stresses and magnitudes of crop loss have been increasing recently. These risks are projected to increase in future affecting food production if agriculture is not adapted to changing climates. The spatio-temporal variation in direction and magnitude of climate change impacts vary with the nature of crops, and therefore the crop-wise impacts and adaptation gains are summarized below.

Rice

Climate change is projected to reduce irrigated rice yields by ~4% in 2020 (2010–2039), ~7% in 2050 (2040–2069) and by ~10% in 2080 (2070–2099) climate scenarios. Whereas rainfed rice yields are likely to be reduced by ~6% in the 2020 scenario, yields may reduce only marginally (<2.5%) by 2050 and 2080. However, spatial variations exist for the magnitude of the impact, with some regions likely to be affected more than others. The study indicated that growing improved varieties with efficient agronomy can lead to an increase in all-India irrigated rice yields by about 17% over current values in the 2020 scenario, by 14% and by 8% in the 2050 and 2080 scenarios, respectively. Similarly, rainfed rice yield can be increased by ~20% in the 2020 and by ~35–38% in the 2050 and later scenarios (Naresh Kumar et al. 2013).

Wheat

Wheat yield in India is projected to reduce by 6–23% by 2050 scenario based on management, if no adaptation is followed. Adaption by timely sowing of suitable variety and with input (fertilizer and irrigation) management may be a practical low-cost adaptation strategy to increase the yield (by >10%) in future climates (Naresh Kumar et al. 2014a). Central India is projected to lose yield despite this adaptation strategy warranting development of varieties highly tolerant to early and terminal heat stress.

Maize

Climate change is projected to reduce irrigated maize yield by 18% in kharif season, but adaptation is projected to increase the yield up to 21% in 2020 scenario (Naresh Kumar et al. 2012).

Sorghum

Climate change is projected to reduce rainfed sorghum yield by 2.5% in 2020 (2010–2039). However, it is projected that adaptation can increase the productivity by 8% in 2020 (Naresh Kumar et al. 2012).

Mustard

In India, mustard yield is projected to reduce by ∼2% in 2020 (2010–2039) if no adaptation is followed (Naresh Kumar et al. 2015). Adoption of a combination of improved agronomic management practices can improve the yield by ∼17% with current varieties (Naresh Kumar et al. 2014b). However, with improved varieties, yield can be enhanced by ∼25% in 2020 climate scenario.

Soybean

Increase in soybean yield in the range of 8–13% under future climate scenarios (2030 and 2080) is projected (Naresh Kumar et al. 2012).

Groundnut

The rainfed groundnut yield is projected to increase by 4–7%, except in the climate scenario of A1B 2080 under which yield is projected to reduce by −5% (Naresh Kumar et al. 2012).

Potato

The potato yield is projected to reduce by ~2.5, ~6 and ~11% in 2020 (2010–2039), 2050 (2040–2069) and 2080 time periods, respectively, in the Indo-Gangetic Plains. Change in planting time is found to be the most important adaptation option for yield improvement by ~6% in 2020 (Naresh Kumar et al. 2015).

Cotton

Cotton productivity in northern India is projected to marginally decline due to climate change, while in Central and southern India, productivity may increase implying that the overall productivity at the national level may not be affected (Hebbar et al. 2013).

Coconut

Coconut productivity is projected to increase in western coastal region, Kerala, parts of Tamil Nadu, Karnataka and Maharashtra (with current level of water and management) while negative impacts are projected for Andhra Pradesh, Orissa, West Bengal, Gujarat and parts of Karnataka and Tamil Nadu due to climate change. On all-India basis, climate change is projected to increase coconut productivity by 1.9 to 6.8% in 2080 scenario. Adaptation can increase the productivity by ~33% in 2030, and by 25–32% in 2080 climate scenarios. Analysis further indicated that current productivity in India can be improved by 20% to almost double if all plantations in India are provided with location specific agronomic and genotype interventions (Naresh Kumar and Aggarwal 2014).

Horticultural Crops

Climatic stresses such as extreme temperatures, hailstorms and heavy rainfall events damage horticultural crops. A 24 h flooding affects tomato crop and the flowering period is highly sensitive . In case of onion, bulb initiation stage is sensitive to flooding causing a 27 and 48% reduction in bulb size and yield, respectively (Rao et al. 2009). Productivity of temperate fruit crops such as apple is affected, and its cultivation is shifted to higher latitudes to 2500 mamsl from 1250 mamsl in Himachal Pradesh (Bhagat et al. 2009).

Climate change is projected to affect the quality in terms of reduced concentration of grain protein (under low fertilizer input conditions), and some minerals like zinc and iron due to elevated CO2 (Porter et al. 2014). Elevated CO2 caused reduction in the concentration of protein, secondary metabolites, while rise in temperature enhanced their concentration in pulse, several vegetable and fruit crops. Majority of studies indicate negative impacts; however, rise in temperature may decrease cold waves and frost events leading to reduced damage to frost-sensitive crops such as chickpea , mustard , potato and other vegetables.

3 Strategizing Crop Improvement for Adaptation

Crops have been adapting to external stresses; however, in the climate change scenario, the frequency of climatic stresses has been increasing posing serious threat to crop productivity. Several researchers have expressed concern that current breeding strategies will not be sufficient to meet the challenges of increased frequency of climatic risks . The basic strategy that has so far followed may need a thorough relook so that the climate resilient varieties are developed for meeting the ever-growing demand for food in changing climates (Rajeev et al. 2011; Stephen and Donald 2010a; Chikelu et al. 2012; Smith 2012). Only about 3% of the germplasm is being used for crop improvement. There is a need for involving wider germplasm pool for crop improvement. This implies that the germplasm characterization itself needs to be reoriented so that climatic stress responses are taken into consideration apart from other agronomic characteristics. Increased use of plant genetic resources is expected to play a major role in developing climate resilient agricultural systems (Lin 2011; Hodgkin and Bordoni 2012). Currently, the number of accessions of 612 genera and 34,446 agricultural species conserved ex situ worldwide has reached 7.4 million. However, only less than 30 percent of the total numbers of accessions are estimated to be distinct. Though the number of accessions of minor crops and crop wild relatives (CWR) has increased, they are still generally underrepresented. Moreover, the germplasm erosion is reported from several countries from different types of agricultural crops (Fig. 12.1). Several breeding methods have been successfully employed for crop improvement. However, the use of crop wild relatives in crop improvement efforts is not optimized yet (Ortiz 2002). Genetic diversity available in crop wild relatives needs to be exploited for sustaining and improving the crop yield in dynamic biotic and abiotic stress events (Feuillet et al. 2008) in changing climates.

Fig. 12.1
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Genetic erosion reported in agricultural species (Data used from The Second Report on The State of The World’s Plant Genetic Resources for Food and Agriculture, FAO Report, 2010)

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Under-exploitation of full genetic potential of edible species is a blessing in disguise as the demand for quantity and quality food will continue to increase in future. However, the rate of increase in biodiversity erosion is a major concern. As mentioned earlier, species which cannot adapt to the rate of climate change will become extinct immediately. Species that are able to adapt but at a rate slower than that of change in climate will extinct eventually. This implies that currently exploited species in agriculture and food production system must evolve faster. For this crop improvement, efforts need multipronged approach including conventional breeding, exploitation of full germplasm, molecular breeding , genetic engineering , distant hybridization and exploitation of crop wild relatives , among others. Among these, the use of currently available germplasm and crop wild relatives is of major concern because they are vulnerable to erosion causing serious loss of genetic diversity if extra care and precautions are not taken. Protecting areas of genetic diversity, national gene banks and ex situ and in situ conservation measures are being followed which help in conserving the genetic diversity.

A summary of the major climatic risks , crops in different regions and total germplasm available in different subregions indicate that major stresses and crops are almost common (Tables 12.1 and 12.2). Crops are being increasingly exposed to multiple stresses even in a crop season. Thus, exploiting the available entire germplasm is of utmost importance. Therefore, future crop improvement efforts need new initiatives and dimensions (Fig. 12.2) and some of them are briefly mentioned below:

  • Identification of current and anticipated climatic stresses and prioritizing the crops, traits and regions for crop improvement. For instance, wheat is exposed to early and terminal heat stress in Central India and terminal heat stress in North India (Fig. 12.3). Simulation analysis indicated that timely sowing of wheat with suitable cultivars can improve the wheat yield despite climate change (Naresh Kumar et al. 2014a). However, yield in Central India is projected to be reduced if suitable cultivars are not developed. As per this analysis, development of short-duration and heat stress-tolerant varieties for Central India should be prioritized. Since development of a variety of an annual crop takes at least 8–15 years, it is essential to initiate concerted efforts immediately as by 2050 one may get about only 3–7 breeding cycles.

  • Characterizing entire germplasm of a species in the backdrop of current and anticipated climatic stresses and conditions. There is a need to exploit all available genetic variability within a species with climatic stresses as backdrop. Targeted breeding, as is done in case of droughts, floods , high temperature and salinity stress, also needs to be extended to other types of climatic stresses (Table 12.3). Further, the traits that contribute to reduced GHG emission and enhanced CO2 sequestration need to be identified . In addition to these, there is also a need to identify the climatic threshold for every sensitive phase of crop for developing climate resilient varieties. For instance, a rice analysis for India indicated that in areas with current seasonal (June–September) mean minimum temperatures of >23 °C, as in parts of Central, North and northeast regions of India, future temperatures constrain higher productivity of irrigated rice (Naresh Kumar et al. 2013). Moreover, high as well as low temperature stress coinciding pollination affects the pollen viability eventually reducing the rice yield. Similarly, in case of spring wheat varieties, yield would reduce in areas with mean seasonal maximum and minimum temperatures more than 27 and 13 °C, respectively (Naresh Kumar et al. 2014a). Wheat is identified as the most important crop that needs to be focussed for crop improvement to beat climatic stress effects in South Asia (Lobell et al. 2008). In case of mustard , regions with mean seasonal temperature regimes above 25/10 °C are projected to lose yield due to temperature rise. As climatically suitable period for mustard cultivation may reduce in the future, short-duration (<130 days) cultivars with 63% pod-filling period will become more adaptable (Naresh Kumar et al. 2015). There has been a lot of literature available on this front with specific examples.

    In horticultural crops , the challenge is to retain and improve quality despite climatic stresses. For instance, breeding plantation crops need visionary approach as the plants live for up to 70 years, and one should take the anticipated future climatic stresses, technological improvements, land use change and socio-economic demand for quantity and quality into account. Thus, evaluation of germplasm taking into consideration the response to climatic extremes apart from other criteria becomes essential. Genotypic improvement strategies include population improvement through identified stress-tolerant plants, breeding for temperature stress tolerance of pollen and stigma, high retention of set fruits under climatic risks and improved source-sink balance and identification of multiple stress-tolerant cultivars. In addition, there is a need to understand the change in quality of produce with respect to climate change. Further, the biotic stresses that are anticipated to increase or emergence of new pests must also be taken into consideration while breeding climate resilient cultivars:

  • Identification of climate smart varieties which can meet the challenges of future climates. For example, some of the major challenges include breeding:

    • Low-methane-emitting rice cultivars.

    • Rapid nitrogen uptake and its use efficient varieties for reducing the N2O emission.

    • High water-use efficient varieties.

    • High carbon sequestration varieties for perennial crops, deep and high root volume varieties of annual crops.

    • Stress-tolerant varieties with high revival capacity.

    • Stress avoidance by phenological plasticity.

    • Multiple abiotic and biotic stress-tolerant/stress-resistant varieties.

    • Retaining quality of produce despite climate change.

    • In rice, low-methane-emitting cultivars, cultivars suitable for flood situation, water stagnation and salt tolerance become more important. In maize, cultivars with flood tolerance and endless gap between silking and tasselling gain importance. The farmers’ varieties can be of immense source of tolerance gene pool for use. In plantation crops, identification of in situ tolerant trees (Naresh Kumar et al. 2002) and their use in population improvement programme becomes very important as they have been exposed to climatic stresses during their life cycle and still performed better in terms of physiological parameters and economic yield, indicating the presence of desirable genetic composition.

  • Utilization of crop wild relatives in breeding programme for incorporating desirable genes for climatic stress tolerance. Though crop wild relatives may fail to adapt to new climatic conditions of their native habitats (Jarvis et al. 2008), they possess a gene pool which can be exploited for crop improvement. A number of reviews have taken stock of use of crop wild relatives in crop improvement for tolerance to abiotic stresses and quality (Radden et al. 2015).

  • Identification and utilization of genotypes from climate analogue analysis for a quick intervention. The climate analogue analysis is a concept which is based on identification of areas where either the today’s climate of a location corresponds to the future climate projected at another location or the projected future climate corresponds to the current climate of another site (Ramírez-Villegas et al. 2011). Using this concept, testing the performance of genotypes in climate analogue sites can lead to identification of suitable genotypes for future climates. In addition, germplasm collection can also be rationalized suing climate analogues.

  • Geospatial analysis-based germplasm collection to minimize the gaps in germplasm collection and also to minimize the duplication. Further, geospatial tagging and characterizing germplasm is possible in this approach. Geospatial software such as DIVA is extensively used for this purpose (Hijmans et al. 2001).

  • Distant hybridization using interspecific and intergeneric breeding strategies (Liu et al. 2014).

  • Molecular breeding helps in targeted crop improvement and is relatively faster than conventional breeding. In molecular or marker-assisted breeding, DNA markers are used as a substitute for phenotypic selection and to accelerate the release of improved cultivars.

  • Genetic engineering has to be exploited for gene pyramiding to develop climate resilient varieties (Varshney et al. 2009; Scheben et al. 2016).

  • The use of omics science platforms for crop improvement includes genomics , phenomic platform data, molecular data and bioinformatics tools. The growing number of available high-quality reference genomes and advances in population-level genotyping has contributed to improved understanding of genomic variation. These developments are leading towards plant pangenomics (Scheben et al. 2016).

  • The use of simulation models in climate change research is indispensable for testing the performance of a cultivar in future environments. Several crop models such as DSSAT, InfoCrop, APSIM and Crosyst are being used for quantifying the impacts of climate change on crops (Assenge et al. 2013; Rosenzweig et al. 2014; Naresh Kumar et al. 2012, 2013, 2014, 2015). Further, combining the ecophysiological modelling and genetic mapping is becoming important approach in ‘plant breeding through design’ to predict the performance of genotype and recombinant inbred line population in terms of phenology and physiological traits (Yin et al. 2005).

  • Engineering agroecosystem genetic composition by varietal diversification becomes essential in view of projected increase in climatic stresses and consequent biotic stresses. Varietal diversification can improve the horizontal resistance agroecosystems to climatic and consequential stresses.

  • Engineering agroecosystem genetic composition by crop diversification : Out of over 20,000 species of edible plants in the world, fewer than 20 species provide 90% of our food. A quick analysis indicated that crop diversity ranged from 23 to 80 in major states of India (Fig. 12.4).

Table 12.2 Climatic stresses, major crops and number of total accessions in gene banks
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Fig. 12.2
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Basic steps in development of climate resilient cultivars

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Fig. 12.3
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Impact of climate change on wheat (a) without and (b) with adaptation in 2050 scenario (Naresh Kumar et al. 2014a)

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Table 12.3 Some climate-resilient traits (CRTs) for different types of abiotic stresses
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Fig. 12.4
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Crop diversity in Indian states

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Diversification of food basket and food production systems helps in sustainable food and nutritional security systems in changing climates. There is a need to focus on socio-economic research to delineate the effects of globalization, markets, food habits, policy initiatives and crop diversification.

4 Some Recent Examples of Breeding for Climate Change

  • Common bean biodiversity has been used in plant breeding to develop both heat- and cold-tolerant varieties grown from the hot Durango region in Mexico to the cold high altitudes of Colombia and Peru.

  • Corn genetic resources have been used in breeding varieties adapted to cultivation from sea level to over 3000 mamsl, as in Nepal.

  • Protection of farmers’ varieties as is done for varieties of millets and rice.

  • Cultivar that can tolerate excessive heat during pollination for cowpea and corn and flooding early in the growing season for soybean and rice.

  • Maize hybrids that show better synchronization of pollination and flowering under heat and water stress.

  • Genome sequences are available for many crop species such as rice (Goff et al. 2002; Yu et al. 2002; IRGSP 2005), poplar (Populus trichocarpa) (Tuskan et al. 2006), sorghum (Sorghum bicolor) (Paterson et al. 2009), maize (Schnable et al. 2009), soybean (Glycine max) (Schmutz et al. 2010), cucumber (Cucumis sativus) (Huang et al. 2009), pigeon pea (Cajanus cajan) (http://www.icrisat.org/gt-bt/IIPG/home.html), wheat (http://www.genomeweb.com/sequencing/wheat-genome-sequenced-roches-454) and barley (Hordeum vulgare) (http://barleygenome.org/).

  • Transgenic rice plants overexpressing Arabidopsis CBF3/DREB1A or ABF3 TF showed improved tolerance to drought and salinity without growth retardation (Oh et al. 2005).

  • Using integrated biotechnology approaches, drought-tolerant maize cultivars were developed with about 20–50% higher yields under drought than the current cultivars. Several of them have already reached farmers’ fields in Africa. The high NUE maize cultivars are also being developed (Varshney et al. 2011).

  • To enhance adaptive phenotypic plasticity or yield stability of sorghum and pearl millet in variable climates, traits such as photoperiod-sensitive flowering, plastic tillering, flooding tolerance, seedling heat tolerance and phosphorus efficiency are identified for inducting into the cultivars for West Africa (Haussmann et al. 2012).

  • Diagnostic markers for photoperiod sensitivity gene (Ppd-D1) and vernalization genes (Vrn-A1, Vrn-B1 and Vrn-D1) were used for adaptation of wheat in Australia (Eagles et al. 2010).

  • The Sub1 rice tolerant to flood can survive total submersion for more than 2 weeks, with great benefits to farmers.

  • Introduction of Sub1 QTL resulted in rice varieties that can tolerate flooding for 12–14 days, and these varieties such as Swarna Sub1 are cultivated in over one million hectares.

5 Conclusion

The strategy for adaptation to climate change has to be multidimensional with crops and cultivars as the central themes . There is a need for serious reorientation of breeding efforts to a comprehensive genetic improvement programme for sustaining the crop productivity in changing climates. Characterization of projected climatic stresses, characterization of entire germplasm with projected climatic variability as background, utilization of entire genetic diversity and deploying multipronged approaches for genetic improvement will ensure the enhanced crop production and quality to meet the demands of future climates and population.