Everything you need to know about crop breeding strategies for climate change !
Q. 1. What is climate change?
Ans. Climate change is any long-term significant change in the “average weather” of a region or the earth as a whole. Average weather may include average temperature, precipitation and wind patterns. It involves changes in the variability or average state of the atmosphere over durations ranging from decades to millions of years.
Q.2. What are the main features of climate change?
Ans. Main points related to climate change are listed below:
(i) Climate change has continued throughout the entire history of Earth.
(ii) These changes can be caused by dynamic processes on Earth, external forces including variations in sunlight intensity, and more recently by human activities.
(iii) Climate change is a gradual process which takes very long time, (decades to millions of years)
(iv) In recent usage, especially in the context of environmental policy, the term “climate change” usually refers to changes in modern climate.
(v) Climate includes the average temperature, amount of precipitation, days of sunlight, etc.
(vi) It is believed beyond doubt that human activity is contributing to the current rapid changes in the world’s climate.
Q. 3. What are the factors associated with climate change?
Ans. Climate changes reflect variations within the Earth’s atmosphere; processes in other parts of the Earth such as oceans and ice caps, and the effects of human activity .The external factors that can shape climate are often called climate forcing and include such processes as variations in solar radiation, the Earth’s orbit, and greenhouse gas concentrations.
Weather is the day-to-day state of the atmosphere. On the other hand, climate refers to the average state of weather and is fairly stable and predictable. Climate includes the average temperature, amount of precipitation, days of sunlight, and other variables that might be measured at any given site.
Climate change is the result of several factors such as:
(i) Glaciation,
(ii) Ocean variability,
(iii) Co2 concentration,
(iv) Plate tectonics,
(v) Solar variations,
(vi) Orbital variations,
(vii) Volcanism,
(viii) Fossil fuel,
(ix) Cement manufacture,
(x) Land use (irrigation and deforestation),
(xi) Livestock etc.
According to a 2006 United Nations report, Livestock’s Long Shadow, livestock is responsible for 18% of the world’s greenhouse gas emissions as measured in CO2 equivalents. All the above factors singly or in combination significantly contribute to climate change.
The sun is the source of over 99% of the heat energy in the climate system. Less than 1% of the energy is provided by the gravitational pull of the Moon (manifested as tidal power), in addition to geothermal energy provided by the hot inner core of the Earth. The energy output of the sun, which is converted to heat at the Earth’s surface, is an integral part of shaping the Earth’s climate.
Q. 4. What are the effects of climate change?
Ans. The climate change has two types of effects, viz.:
i. Direct effects and
ii. Indirect effects.
The direct effects of climate change include effect on:
(i) Temperature,
(ii) Rainfall,
(iii) Sunlight
(iv) CO2 concentration, etc.
As a result of change in these aspects in a region, there are indirect effects or change in the:
(i) Pest scenario,
(ii) Disease situation,
(iii) Water availability,
(iv) Day-length,
(v) Biodiversity and
(vi) Cropping pattern.
Q. 5. What is the effect of climate change on temperature?
Ans. There is an increase in temperature which will lead to drought/water deficit conditions. It will promote the incidence of certain types of insect’s diseases and weeds that were not prevailing earlier in a particular region. Extreme temperature expands the desert area. Higher temperatures are expected to improve or retard seed germination, plant growth and/or plant development, depending on the relative sensitivity or tolerance of crop genotypes.
Differences in climatic conditions, such as increases in temperature, will have a direct impact on local insect vector populations. Reproduction, physical activity and metabolic rates would all be increased. These processes would act together to increase the efficiency of vectors and consequently virus spread. In future, the use of insecticides will become restricted and methods to control vectors will require constant innovation.
The severe climate change leads to death or sometimes extinction of some plants and animal species. For example, in the UK during the drought year of 2006 significant numbers of trees died or showed dieback on light sandy soils. In Australia, since the early 90s, tens of thousands of flying foxes (Pteropus) have died as a direct result of extreme heals. Water deficit summers can lead to more periods of drought, potentially affecting many species of animal and plant.
Q. 6. What are the effects of climate change on Rainfall Pattern?
Ans. Climate change predictions are for increased variability of rainfall in many regions worldwide, resulting in greater fluctuations in soil water regime. The climate change may lead to increase or decrease of rainfall over the average value of rainfall in a particular region. The increase in the average rainfall may lead to flood and water stagnation conditions, whereas decrease in average rainfall may cause drought or water deficit conditions. The presence of many of the pathogens in the environment correlates with seasonal temperature and their spread is aided by rainfall.
Q. 7. What are the effects of climate change on days of sunlight?
Ans. The change in the average value of sunlight days in a particular region will have effect on the thermo and photoperiod requirements of the plant species grown in that region. As a result, new set of crop varieties will have to be bred for such situations. Only thermo and photo insensitive varieties can be successful under such situations.
Q. 8. What is the effect of climate change on CO2?
Ans. The global warming and climate change lead to rise in atmospheric CO2 concentration which will have a positive effect on productivity, though in a crop genotype-dependent manner.
Q. 9. What are the effects of climate change on biodiversity?
Ans. Climate change and biodiversity interact in many important ways. In some cases, life cycles of many wild plants and animals are closely linked to the passing of the seasons. If two species are interdependent (e.g. a wild flower and its pollinating insect), climatic changes can disturb their synchronization. For example, if one has a cycle dependent on day length and the other on temperature or precipitation. In principle, at least, this could lead to extinctions or changes in the distribution and abundance of species.
Several organizations such as Wildlife Trust, World Wide Fund for Nature, Birdlife International and the Audubon Society are actively monitoring and researching the effects of climate change on biodiversity and advance policies in. areas such as landscape scale conservation to promote adaptation to climate change are being framed.
Q. 10. What breeding problems are expected to emerge due to climate change?
Ans. Gradual change in the climate over a long period will lead to several new problems such as appearance of new insects, new diseases, new weeds, high temperature, drought conditions, change in rainfall etc.
As a result of climate change, the following problems emerge:
(i) Water scarcity or excess depending upon the change in the rainfall pattern.
(ii) Drought if there is low rainfall and increase in temperature.
(iii) Change in response to thermo and photoperiods depending upon the change in sunlight and day length.
(iv) Appearance of new insects, diseases and weeds in the changed climate.
(v) Change in the adaptation of cultivars in the areas of climate change.
(vi) Change in the cropping pattern in the region of climate change.
Such types of changes will require new set of crop cultivars for successful crop production. To keep pace with the climate change, breeders have to make continuous concerted efforts. The climate change needs to be converted from a difficulty into an opportunity.
Q. 11. What are the sources of resistance to climate change?
Ans. In crop plants, there are five important sources which can be used for developing suitable cultivars for cultivation in the region where climate change is taking place.
The sources include:
(i) Germplasm collection,
(ii) Cultivated varieties,
(iii) Wild species and relatives of crop plants,
(iv) Induced mutations, and
(v) Transgenes.
These are briefly discussed below:
(i) Germplasm Collections:
Germplasm Collections are the potential sources that can be effectively used in developing suitable crop cultivars for areas of climate change. The new cultivar has been developed, to solve the specific problem or a set of problems, using appropriate breeding techniques.
(ii) Cultivated Varieties:
Crop cultivars can also be developed using obsolete or current crop varieties. Again the cultivar has to be developed to combat the problem of specific disease or insect or weed, or drought, or water stagnation that has emerged as a result of climate change. In the past, cultivated crop cultivars have been effectively used for developing varieties resistant to above mentioned changed situations.
(iii) Wild Species and Relatives:
Wild Species and Relatives of cultivated plants are potential sources of developing crop cultivars suitable for climate change. However, use of these poses several problems such as cross in compatibility, hybrid in viability and hybrid sterility. Hence, such sources are rarely used,
(iv) Induced Mutations:
Induced mutations are potential sources of developing crop cultivars suitable for climate change. In the past, induced mutations have been successfully used for developing varieties resistant to diseases and insects in several crop species.
(v) Transgenic Technology:
Transgenic plants can be used to combat the problems arising due to climate change. Crop cultivars resistant to various insects and diseases can be developed through the use of transgenic technology.
Q. 12. What breeding approaches should be adopted for developing varieties suitable for climate change?
Ans. Traditional breeding approaches will continue to develop cultivars suitable for climate change. These approaches include introduction, selection, hybridization and mutations.
In developing suitable crop cultivars for climate change due importance should be given to:
(i) Development of MAR lines,
(ii) Genetic enhancement,
(iii) Transgenic technology,
(iv) Durable resistance, and
(v) Crop adaptation.
Q. 13. What is the role of MAR lines in developing varieties suitable for climate change?
Ans. Emphasis should be given to develop crop cultivars with multiple adversities resistance. This may include resistance to insects, diseases, drought and excessive moisture. This includes both breeding for multiple insects’ resistance (MIR) and breeding for multiple disease resistance (MDR).
Q. 14. Describe the role of genetic enhancement and transgenic breeding in developing varieties suitable for climate change?
Ans. Genetic enhancement can be used in developing novel genetic diversity that can be used in breeding crop cultivars suitable for climate change. Transgenic breeding can be successfully used for developing crop cultivar resistant to diseases, insects and drought conditions arising due to climate change.
Q. 15. Explain the role of durable resistance and crop adaptation in developing varieties suitable for climate change?
Ans. Plant breeders should make use of long lasting resistance (durable resistance) for developing insect and disease resistant varieties. Multi-lines can be used for achieving such goal. Maintaining food production under conditions of climate and environmental change will require the breeding of new crop varieties better adapted to these conditions. Heterogeneous crops also exhibit greater stability across environments. The best sources of pest and pathogen resistance can be further enhanced by deployment in such mixed crop stands.
For climate change, crop cultivars with wide adaptation should be selected based on multi-location under diversified environmental conditions for 3-years. In other words, crop adaptation should be given due importance in developing varieties suitable for climate change. Breeding strategies for different situations of climate change are presented in Table 29.2.
Q. 16. How would you screen the material for resistance to climate change?
Ans. The screening of breeding material can be carried out looking to the new problem arising as a result of climate change. The new problems may include heat, drought, excessive moisture, new insects, new diseases and new weeds. The standard procedures available can be adopted for screening of material to tackle these problems.
The material can be screened under both natural and controlled conditions to select genotypes suitable for a particular situation. Under artificial conditions the screening of breeding material should be carried out under controlled conditions representing climate change.
Q. 17. What should be the future breeding strategies for developing crop cultivars suitable for climate change?
Ans. The climate change is occurring at the global level. As a result, India is facing a climate change of considerable magnitude.
It is envisaged that as the twenty-first century progresses, there will be:
(i) Rise in temperature ranging from 2 to 6 degree Celsius. The level of warming will be higher in the northern part of India than in the southern parts;
(ii) Rapid increase in night temperatures compared to day temperatures;
(iii) Increase in rainfall (15 to 40%) over all the states, especially those in the western and central-west parts of India, excepting Punjab, Haryana, Delhi, Rajasthan and Tamil Nadu.
In view of the climate change in India, the future plant breeding efforts need to be directed towards the following thrust areas:
i. The new crop varieties should be tolerant to drought and heat that are caused due to increase in temperature. Crop breeding programs to develop temperature and drought-tolerant high yielding cultivars of the identified crops should be initiated urgently, so that the desired kinds of crop cultivars are available when effects of climate change are noticed.
ii. The new varieties, especially grown during winter season should have characteristics of early flowering, photo- and thermo-insensitivity, early maturity and high productivity.
iii. The plant genetic resources, especially land races from those areas .that have similarities with climate change can be used to start breeding programs for developing varieties suitable for climate change.
iv. The new crop cultivars for climate change can be developed using a combination of conventional breeding approaches, marker assisted selection, induced mutations and transgenic-breeding, Crop based coordinated programs need to be launched to develop early- maturing, high-yielding and temperature and drought tolerant varieties as early as possible.
v. The desirable genotypes for climate change can also be selected in the breeding populations of some ongoing research programs. There will be need for identification of areas where the climate change conditions already exist or resemble. In such areas, large segregating breeding populations can be screened for selection of desirable genotypes.
Q. 18. Cite some examples of practical achievements of breeding for climate change.
Ans. In the past, several cultivars in different crop species have been developed with resistance to various insects, diseases and drought. Conventional breeding approaches along with modern crop improvement techniques will be rewarding to solve various problems that arise in future as a result of climate change.
Progress has been made in the genetic dissection of flowering time, inflorescence architecture, temperature and drought tolerance in certain model plant systems and by comparative genomics in crop plants. Recently, the Indian Agricultural Research Institute, New Delhi has released an early-maturing wheat variety suitable for late planting.