Authors: S. Lal and N. Ahmed
India with diverse soil and climate comprising several agro-ecological regions provides ample opportunity to grow a variety of horticultural crops which form a significant part of total agricultural produce in the country comprising of fruits, vegetables, root and tuber crops, flowers and other ornamentals, medicinal and aromatic plants, spices, condiments, plantation crops and mushrooms. It is estimated that all the horticulture crops put together cover nearly 11.6 million hectares area with an annual production of 91 million tonnes. Though, these crops occupy hardly 8% of the cropped area in India with approximately 30% contribution in agricultural GDP. Export of medicinal plants, fruits and. After independence there has been seen marked growth in area and production of fruit crops but on the other hand productivity has left far behind as compared to advanced countries. The low productivity is mainly attributed to several factors including environmental, physiological and biological. But over the years, environmental changes playing a significant role like occurrence of erratic rain and snowfall, droughts increase in temperature etc resulting in variation in the fruit production. A significant change in climate at global and national level is certainly impacting horticulture and affecting our fruit production and quality. But understanding of impact of climate change on perennial horticultural production system and the potential effects on fruit quality have drawn a little attention of researchers. The consequences of such rapid change are - global warming, change of seasonal pattern, excessive rain, melting of ice cap, flood, rising sea level, drought, etc. leading to extremity of all kinds. Decrease in potential yields is likely to be caused by shortening of the growing period, decrease in water availability and poor vernalization. Western Ghats and surrounding regions may be deprived of normal precipitation due to abnormal monsoon. Vulnerability, rarity and rapid extinction of plant species will be among the other consequences. Plains of India will face similar kind of problems. Nobel Laureate Pachauri said, total agricultural land will shrink and the available land may not remain suitable for the present crops for too long. Farmers have to explore options of changing crops suitable to weather. He also pointed out that climatic changes could lead to major food security issues for a country like India.
Impact of climate change (specific case)
Temperate fruit crops:
The IMD monitoring reveals that temperatures are increasing in both Jammu region and Kashmir valley, with significant increase in maximum temperature of 0.05 Celsius per year. The average mean temperature in Kashmir has risen by 1.45° Celsius in last 28 years while in Jammu region, it has increased by the rise is 2.32° Celsius.
As a result of rise in temperature and decline in rainfall, the apricot and cherries are fast disappearing from some areas of Kashmir Valley. Due to general rise temperature and less availability of water, the yield and quality of apples in valley and mid temperate region of Jammu are fast deteriorating. Over the last few years, there has been distinct slow growth in production and productivity in rain-fed Kashmir’s Karewas areas. Due to unusual hailstorms and windstorms in summer fruits like cherry, apple, plum, peach and apricot are getting damaged heavily.
In recent years there marked change in the pattern of snowfall in Kashmir which is effecting all the pome and stone fruits. It has been observed that the snowfall and flowering in some years is coinciding leading to great loss in quantity and quality. Due to shortage of water for agronomic crops like rice shift has been recorded from agronomic crops to temperate fruits and nut in J&K as fruit crops are more remunerative as compared to agronomic crops.
In Himachal Pradesh, the study examines the impact of climate change in recent years on apple indicated its cultivation shifting towards higher altitudes. It is evident from the data that temperature in apple growing regions of Himachal Pradesh showed increasing trends whereas precipitation decreased over years. The chill units calculated showed decreasing trends of chill units upto 2400 msl from Bajaura in Kullu at 1221 msl to Sarbo in Kinnaur at 2400msl. The Dhundi station situated at 2700 msl showed increasing trend of chill unit at the rate of 25.0 CUs per year. The increasing trends of chill unit at 2700 msl suggested that area is becoming suitable for apple cultivation in higher altitude. These findings have also been supported by the farmers’ perceptions which clearly reflected that apple cultivation is expanding to higher altitude in Lahaul & Spitti. The average land use per farm in Lahual and Spitti showed more than two percent shift towards apple cultivation but it showed reverse trend in other apple growing regions. The income of the farmers increased more than 10 percent in Lahual & Spitti whereas it showed a decrease of more than 27 percent in Kullu and Shimla districts from fruits in recent decade compared to 1995. The secondary data on area under apple cultivation also compounded statement that apple cultivation is expanding in Lahaul & Spitti in recent decade (Singh et al., 2005).
In Uttarakhand the area under apple cultivation has drastically been reduced. It might be due to less rainfall and higher temperature in winter. It is causing major problem of chilling requirement which is very important to meet for higher and quality production of apple.
Effects on sprouting
The impact of temperature change is most in apple and almond where trees sprout 2-3 weeks early but normally apples trees sprout in mid April. As a result last few years about 70 per cent of trees began to open their buds in mid March. At the end of March it can definitely become very cold again. At this time most trees have their buds open are very susceptible to frost damage.
Effect on fruit color
In Kashmir valley, the failure of apples to change into their specific red shades, or an increase of apples with sunburn. The deep red colour is a result of low temperatures during the night in autumn, just before harvesting. If the temperatures are not low enough, most apples fail to turn into their specific red shades. For many apples their red colour is a trademark of quality but Ladakh province becomes potential area for apple cultivation due to climate change.
Effect on chilling requirements
Most deciduous fruit trees need sufficient accumulated chilling, or vernalisation to break winter dormancy Inadequate chilling due to enhanced greenhouse warming may result in prolonged dormancy, leading to reduced fruit quality and yield. The low warming scenario is less than 1 °C is unlikely to affect the vernalisation of high-chill fruit (Apple, walnut, apricot almond, cherry varieties), and if warming scenario exceeds 1.5 °C and would significantly increase the risk of prolonged dormancy for both stone-fruit and pome-fruit. Japanese plums have a CR of between 500-800, while European cultivars have a CR in excess of 1,000 hours. Periods of mild weather can upset the accumulated CR requiring further periods of cold weather to achieve sufficient hours. Mild winters may result in delayed or irregular flowering, reduced fruit set and an extended flowering period. The CR is a major concern in the marginal temperate area of North Western Himalayas where fruit trees with a low CR have to be grown. Therefore in some areas, it is impossible to grow cherries. For example, sweet cherry requires the accumulation of 1000chill units at 3.8°C in order to complete or ‘break’ dormancy. If chilling is inadequate, the development and/or the later expansion of leaf and flower buds may be impaired. Problems have already been experienced with poor cropping of blackcurrant after mild winters and the same might happen with raspberry, apple and other fruits as winter temperatures continue to increase.
Effect on pollination
More than 70 per cent of orchards have less than 20 per cent pollinizer proportion, whereas a minimum of 30-33 per cent is required in our agroclimatic conditions for good fruit set. Moreover there is lack of diversity in pollinizing cultivars as mainly Golden Delicious and Red Gold are being predominantly used which have attained biennial bearing tendency and their bloom seldom coincides with the flowering period of Delicious cultivars. The population of natural pollinators has gone down due to indiscriminate use of pesticides and deterioration in ecosystem. Managed bee pollination is very limited and available bee hives during bloom hardly meet 2-3 per cent of the demand. All these factors have lead to poor fruit setting of Delicious (Kjøhl et al 2011).
Fruit ripening
High temperatures on fruit surface caused by prolonged expo- sure to sunlight hasten ripening and other associated events. One of the classical examples is that of grapes, where berries exposed to direct sunlight ripened faster than those ripened in shaded areas within the canopy. For fruits exposed to direct sunlight, pulp temperatures reached 35 0C and required 1.5 days longer to ripen than those than grew in the shade (Woolf et al., 1999). Cell wall enzyme activity (cellulose and polygalacturonase) was negatively correlated with fruit ?rm-ness, indicating that sun exposure, i.e., higher temperatures during growth and development, can delay ripening. However this delay did not occur via a direct effect on the enzymes associated with cell wall degradation. In apples, treatments of 38 and 40 0C for 2-6 days did not have marked effects on respiration, although ethylene production was reduced. High temperatures on fruit surface caused by pronounced exposure to sunlight can hasten ripening and other associated events.
Physiological disorders and tolerance to high temperatures
Frequent exposure of apple fruit to high temperatures, such as 40 oC, can result in sunburn, development of watercore and loss of texture. Moreover, exposure to high temperatures on the tree, notably close to or at harvest, may induce tolerance to low-temperatures in postharvest storage. (Buescher, 1979; Hickset et al., 1983)
Effects of Higher CO2 & GHG on fruit yield and quality
Carbon dioxide is important because carbon atoms form the structural skeleton of the plant. A doubling of carbon dioxide levels may increase plant growth by 40-50% though continuous high levels saturate the plant’s ability to use carbon dioxide and the benefits decrease with time. If other factors remain favorable, increased carbon dioxide concentrations will lead to greater rates of photosynthesis in plants. Current carbon dioxide concentrations limit plant photosynthesis. Growers of protected horticultural crops have already aware from so many years that artificially raising the concentration of carbon dioxide up to certain stage in greenhouses can substantially increase crop growth and yield.
Effect on timing of bud burst, cessation of growth, altered concentrations of carbohydrates and plant hormones in turn altered the dormancy status of trees thereby changing the timing of bud burst and the length of the active growing period. Flowering and fruiting of trees are likely to be hastened under conditions of elevated carbon dioxide. The evidence for an effect of carbon dioxide concentration on leaf senescence and leaf fall is rather contradictory and may be species dependant Most predictions of the direct effects of carbon dioxide suggested that average yields will increase by about 40-50% with a doubling of carbon dioxide concentrations Leaves are able to detect and respond rapidly to carbon dioxide concentration. Stomata opening decreases in response to increased carbon dioxide concentration.
Effect on incidence of insect, pest and disease
Erratic changes in temperature and precipitation leads to more incidences of insect, pest and disease. In the last few years, the attack of apple scab, powdery mildew in apple, flee beetle in almost all the temperate fruit crops has been increased.
Interaction effect of temperature and carbon
The combination of increased temperature and increased carbon dioxide predicted in all climate change scenarios suggests that for some species the growth stimulation may be greater than the 40-50%. The doubling of carbon dioxide concentration combined with a 3°C increase in temperature could lead to 56% stimulation in growth.
Subtropical and tropical fruit crops
Mango
Climate and weather play critical roles in the economic success or failure of tropical fruit tree species including commercial mango production. Air temperature and rainfall influence vegetative and phenological phases in mango and are two of the most important factors determining suitability of an area’s climate for mango production. Climate-related changes have already brought widespread changes in flowering and fruiting patterns of mango. This is adversely affecting fruit production in some areas. But rising temperature in areas previously too cold for mango production are making them more suitable for mango production. For instance, an increase in temperature the during coldest month has made mango cultivation possible in the valley areas of Himachal Pradesh and Uttarakhand. In several parts of the globe increasing temperature will offer opportunities for mango production in new areas.
Fig.1: Effect of temperature on the duration of growth and on the relative growth rate of leaves of two mango cultivars
Fig2: Negative effect of temperature on inflorescence size and number of flowers per inflorescence
Citrus
Citrus fruit plants are considered to be better equipped to deal with a changing climate than other fruit crops. That’s largely because they flourish in the heat. According to a 2007 study that examined the effect of rising temperatures on various crops, the cultivation area for orange trees will actually expand by the year 2055. While the lemon cultivation area will shrink by around 10 percent, that is a small setback in comparison to other plants. Strawberry producers, for example, will lose around 32 percent of their arable land, and wheat fields will be eroded by around 18 percent, according to the study. "For the lemon harvest, we’re not expecting any major drawbacks due to climate change for the time being," according to Tim Grout from Citrus Research International, a research association that examines the citrus industry . "If however temperatures rise by more than one or two degrees, yields could fall because the plants shed their fruit too soon," he says, adding that seedless lemons are especially at risk. Other analysts believe that the increased risk of pest infestations could also lead to greater harvest losses. Citrus greening, for example, is a bacterial disease that is primarily spread by two types of psyllid insects. It turns a citrus plant’s leaves and shoots yellow and makes the fruit bitter, often causing the entire plant to wither away.
But in different case in District Kangra, Himachal Pradesh, citrus fruit production has declined by 1,000 tonnes in the district in the last two years. "In 2009-10, it was 22,184 tonnes while in 2010-11 it decreased to 21,704 tonnes," district horticulture authorities said. "Climate change is one major factor affecting the fruit crop. We are facing problems on this count for the last eight to ten years. It's not raining in time because of which, plants are not getting proper nutrition and fruition is declining gradually," said Ramesh, an orange grower from Indora.
Banana
Bananas are of tropical origin >70% of global land areas (mainly tropical areas), but there could be gains towards subtropics. Potentially huge impact on banana production, both in tropical and subtropical regions Review of the impacts of climate change on Musa (Bergh et al. 2012) suggests that future climates will be less suitable in? when grown in subtropics, they are subject to strong environmental constraints, mainly low temperature but also drought Temperature and rainfall are expected to change at unprecedented rate in coming decades (IPCC, 2007).
Litchi
The aberrant weather and extreme events may damage the crop completely. The observed temperature trends in the region of litchi production (Bihar) showed a general increase in temperature in order of 2-3oC overt the base period of 50 years. The unusual impact of climate change has been witnessed in litchi production system as noted in flowering pattern (shifted early), fruit growth and harvesting periods.the occurrence and the extent of damage by physiological disorders and resurgence of pest are very much dependent on the temperature and humidity variations in the atmosphere ( Kumar and Nath 2013).
Grape
Grape is one such crop that is highly sensitive to climatic changes. The elevated CO2 levels may increase productivity in arid and semi-arid regions but, the drought stress caused by higher evaporative demand may override beneficial effects of increased CO2 in the atmosphere unless irrigation can be steeped up to compensate these effects. Higher temperature may advance the ripening of berries and alter the berry composition in both table and wine grapes, thereby affecting the quality of the produce. Another dimension to climate change is that the pathogens may become more virulent and/or the plants may become more susceptible, thus increasing disease severity. New pathogens may also emerge or the existing once may mutate/develop resistance. Unseasonal rains may lead to serious downy mildew incidence as evidenced by decrease in productivity during the recent years from more than 25 tons per hectare to 9.2 tons per hectare in the previous season. There is also likelihood of change in the incidence and pattern of insect pests like mealy bug, thrips and mites. Similarly the disease incidence pattern is also likely to be affected with the change in climate as has been observed in case of downy mildew (NRC grape Vision 2050)..
Climate change will impact fruit industry and regions through all of the following
• Changes in the suitability and adaptability of current cultivars as temperatures change, together with changes in the optimum growing periods and locations for fruit crops
• Changes in the distribution of existing pests, diseases and weeds, and an increased threat of new incursions
• Increased incidence of physiological disorders such as tip burn and blossom end rot
• Greater potential for downgrading product quality e.g. because of increased incidence of sunburn
• Increases in pollination failures if heat stress days occur during flowering
• Increased risk of spread and proliferation of soil borne diseases as a result of more intense rainfall events (coupled with warmer temperatures)
• Increased irrigation demand especially during dry periods
• Changing reliability of irrigation schemes, through impacts on recharge of surface and groundwater storages
• Increased atmospheric CO2 concentrations will benefit productivity of most fruit crops, although the extent of this benefit is unknown
• Increased risk of soil erosion and off-farm effects of nutrients and pesticides, from extreme rainfall events
• Increased input costs - especially fuel, fertilisers & pesticides
• Additional input cost impacts when agriculture is included in an Emissions Trading Scheme (ETS)
Priorities for Indian fruit industry in Adapting to Climate Change
• Identify and build on successful strategies of adaptation by the fruit sector to climate changes already experienced.
• Obtain regional climate change scenarios (downscaling) for all fruit growing regions (to 2030) - update as improved scenarios become available.
• Develop Impact Assessments for all or major commodities in these regions.
• Assess the Vulnerability of all or major regions and/or fruit commodities and Identify current "at risk" production sites (regions) and/or industries.
• Identify the long-term (2030 and 2070) opportunities and threats to horticultural regions and cropping systems, as a consequence of climate change - long term adaptation.
• Develop (in consultation with growers and their advisors), Adaptation Strategies which are appropriate, practical, and economically sound.
• Review and/or develop where necessary, Best Management Practices (BMP), Good Agriculture Practices (GAP) for fruit cultivation, which include adaptation and mitigation components.
• Assess the economic benefits of silvi-horti as well as the benefits it might bring for adaptation and mitigation.
• Document the effects of climate change for major overseas production regions, especially in those countries that are major competitors to India’s production.
• Identify additional export opportunities for Indian growers
• Identify alternative regions that may be suitable for production, to take advantage of these market opportunities.
• Investigate the "food miles" concept and the effects decisions on markets and production opportunities for horticulture.
• Develop horticulture specific forecasting tools that can be used for climate change and climate variability (especially temperature variability) related decision making at a farm and regional scale
Adaptation strategies for mitigating effect of climate change
I. Breeding strategies
• Pheno-typing of all important fruits genetic wealth to enhancing temperature, moisture stress and genetic enhancement for tolerance to biotic and abiotic stress.
- Varieties and rootstocks will be evaluated under controlled temperate moisture stress etc. gradient to identify suitable cultivars of all major fruit crops. Experiments on varietal evaluation will also be conducted under natural conditions at different altitudes/conditions (with natural variations in temperature and moisture falling under various agro-climatic zones of the countries.
• Marker assisted selection and development of transgenic having resistance to biotic and abiotic resistance.
• Development of genotypes having resistance to heat and drought.
• Crop diversification.
II. Agronomic management strategies
• Assessment of the vulnerability and climate risks associated with temperate fruit production system in temperate, tropical and subtropical region.
• Development of cropping systems under various agro-climatic conditions.
• Improvement in the irrigation and drainage systems.
• Development of appropriate tillage and intercultural operations.
• Integrated nutrient management.
• Integrated pest management.
• Integrated weed management.
• Development of water harvesting techniques.
III. Biotechnological innovative strategies
• Molecular characterization for various traits in relations to biotic and abiotic stress.
• Transformation of plants from C3 to C4 plants.
• Gene pyramiding against biotic and abiotic stress.
• In vitro conservation of rare and useful species for future use.
- Mitigation strategies for higher CO2/GHG
• Assessment the carbon sequestration potential of perennial fruit crops production system.
Table 2: Estimates of standing biomass per area (t/ha or Mg/ha), and calculated CO2 equivalents per ha for perennial crops.
• To participate in the international dialogue about greenhouse gas emissions management, global warming and sustainable energy development
• Use of biofuel like diseal from Jetropa and Pongamia sp.
• The development of nuclear energy
• The improvements in the efficiency of electricity generation, transmission and distribution
• The use of fuels with lower carbon content, e.g., natural gas, CNG, Gobber gas
• Fuel switching, appliance efficiency and use of renewable energy;
• Tree planting and forest management;
• Waste processing
Future research strategies for optimizing production under changing climate scenario
I. Crop improvement strategies
• Utilizing the current and future regional climatic scenarios of the tropical subtropical and temperate region a micro-level survey of agro-climatic zones of country should be conducted to identify sensitive regions with high vulnerability with respect to different fruit crop.
• Utilization of wild species and relatives in all the fruit crops.
• Introduction of low chilling cultivars of pome, stone and nut fruits.
• Diversification with other high value fruit crops like peach, apricot, walnut, kiwi and olive.
• Development of new genotypes having resistance to high temperature and CO2 concentrations.
• Marker assisted selection and development of transgenic having resistance to biotic and abiotic resistance.
• Development of genotypes having resistance to heat and drought.
• Biotechnological approaches for multiple stress tolerance will be standardized.
II. Development of agro-techniques
• Assessment of the impact of elevated temperature and CO2 on growth, development, yield and quality of commercial fruit crop using open top chamber (OTC) facilities and free air CO2 enrichment system (FACE).
• Sensitive stages of crops to weather aberrations will be identified.
• The phenology of all major fruit crops under changing climate will be monitored.
• In-situ soil moisture conservation practices including indigenous technical know-how will be validated to mitigate the impact of drought.
• Development of suitable agronomic adaptation measures for reducing the adverse climate related production losses.
• Study the impact of climate change and development of technologies on water productivity
• Identify and develop good practices to enhance the adaptation of crop to increased temperature, moisture and nutritional stress.
• Identification and mapping of climate resilient as well as climatically vulnerable micro-niches in all fruit growing regions regions.
• Extreme events, such as late spring frost or windstorm, may cause crop failure. Future climate may also increase occurrence of extreme impacts on crops, e.g. weather conditions resulting in substantial reduction in yield and quality (for example severe drought or prolonged soil wetness).
• To develop a set of high resolution daily based climate change scenarios, suitable for analysis of agricultural extreme events
• To identify climatic thresholds having severe impacts on yield, quality and environment for representative crops and to assess the risks that these thresholds will be exceeded under climate change
III. Plant protection strategies
• Assessment of the pest and disease dynamics, study of disease triangle and development of prediction models
• Strengthen surveillance of pest and diseases.
• Development of ecofriendly pest- ecologies and management strategies and early warning systems.
IV. Post harvest management strategies
• Development of cost effective storage techniques.
• Development of varieties having longer shelf life.
• Studies on mitigation of post harvest spoilage.
V. HRD & creating awareness
• Organize seminars/symposia/trainings and conduct field
demonstrations, on effective climate resilient technologies.
Conclusion
Climate change impacts are to be looked not in isolation but in conjunction with all the aspect of agriculture and allied sectors. The effects of climate change on horticulture sector are still uncertain. In the light of possible global warming, researchers should more emphasis on development of heat- and drought-resistance crops. Research is needed to define the current limits to these resistances and the feasibility of manipulation through modern genetic techniques. Both crop architecture and physiology may be genetically altered to adapt to warmer environmental conditions. . At the regional level, those charged with planning for resource allocation, including land, water, and agriculture development should take climate change into account. The continuation of current and new initiatives to research potential minimize the effects of climate change at farm, regional, national and international level and will help to provide a more detailed picture of how world horticulture and agriculture could change. Only then may we see the implementation of policies and other adaptations in agricultural systems that would minimize the negative effects of climate change and exploit the beneficial effects.
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Vision 2050, NRC Grape, ICAR, Pune, Maharashtra, India
About Author / Additional Info:
Presently actively working in fruit crops improvement research.