Dr. Vivak Arya & Dr. P. K. Rai
Climate variability has been a threat to the mankind and will have likely impact on agriculture production system. It also impacts the horticultural corps, due to erratic rainfall, more demands for water, and enhanced biotic and abiotic stresses. But some research are giving ideas that the changes will not be only harmful, as enhanced CO2 concentration may increase faster photosynthesis and increased temperature may hasten the process of maturity. The earth is the only planet in our solar system that supports life, because of unique environmental conditions that are present-water, an oxygen-rich atmosphere, and a suitable surface temperature. It has an atmosphere of proper depth and chemical composition. About 30% of incoming energy from the sun is reflected back to space while the rest reaches the earth, warming the air, oceans, and land, maintaining an average surface temperature of about 15oC.The chemical concentration in atmosphere for nitrogen is 78%; about 21% in oxygen, which all animals need to survive; and only a small (0.036%) is made up of carbon dioxide which plants require for photosynthesis.
Effect of Climate Change on Horticultural Crops
The vulnerability of any sector to climate change depends on both the expected regional climate change and the sector’s ability to adapt. The projected increases in temperature, variability in precipitation patterns, increase in frequency of extreme weather events such as heat, cold waves, frost days, droughts, floods would severely affect the production of horticultural commodities. These stresses at different crop developmental phases in varying intensities would ultimately determine productivity and quality. The emission of carbon dioxide due to anthropogenic activities has enriched the atmosphere. The carbon dioxide enrichment influences the carbon fixation and productivity of crops. The various impacts need to be addressed in concerted and systematic manner in order to prepare the horticulture sector to face the imminent challenges of climate change would lead to higher respiration rate and partitioning of photo synthates to economic parts. In developing countries, which are predominantly located in lower latitudes, temperatures are already closer to or beyond thresholds and further warming would reduce rather than increase productivity. The extreme weather events of hot and cold wave conditions have been reported to cause considerable damage to many fruit crops. In perennial crops like mango and guava, temperature is reported to have influence on flowering. The rise in temperature will hasten nutrient mineralization in soils, decrease fertiliser use efficiency. Increase in temperature at fruit maturity lead to fruit cracking and burning in litchi and premature ripening of mango.
Impact of Climate Change on Vegetables Crops
Indian climate is dominated by the monsoon, responsible for most of the region’s precipitation, poses excess and limited water stress conditions. Vegetables being succulent are generally sensitive to environmental extremes and high temperatures, limited and excess moisture stresses are the major causes of low yields. Under climate change scenarios the impact of these stresses would be compounded. In tomato, high temperatures can cause significant losses in productivity due to reduced fruit setting, smaller size and low quality fruits. Optimum daily mean temperature for fruit setting in tomato has been reported to be 21-24 oC. Low temperatures favours female flower production, which is desirable and high temperatures lead to production of more male flowers. The duration of onion gets shortened due to high temperature leading to reduced yields. Cauliflower performs well in the temperature range of 15-25 o C with high humidity. Any soil warming would be advantageous for cucurbits, which are generally direct seeded and have a high heat requirement. The rise in temperature will influence survival and distribution of pest population; developing new equilibrium between alternate host crops and pests; hasten nutrient mineralization in soils; decrease fertilizer-use efficienffcy; and increase evapotranspiration with reduced water-use efficiency. The net effect of climate change on horticultural crops will depend on interaction effects of rise in temperature and CO2 concentration in atmosphere.
Simulation Models for Impact Assessment
In the event of working out adaptation and mitigation strategy, it will be appropriate to utilize modelling tools for impact analysis for various horticultural crops. Availability and development of good simulation models for horticultural crops (fruits and vegetables) is lacking in India probably with exception of potato and coconut. Innovative methods are required to develop simulation models for important horticultural crops like mango, grape, apple, orange citrus, litchi, guava, etc.
Gene Manipulation
In addition to employing modified crop management practices, the challenges posed by climate change could be tackled by developing tolerant varieties. Several institutions have evolved hybrids and varieties, which are tolerant to heat and drought stress conditions. They must be used very effectively to combat the effect of climate change depending upon their performance in a given agro-ecological region. Efforts should be intensified to develop new varieties suitable to different agro-ecological regions under changing climatic conditions.
Mitigation Strategies
Climate change is a reality and there is enough evidence to show that the emission of greenhouse gasses has caused global warming and associated climate change. In addition to adapting the horticultural production systems to adverse impacts of climate change, Horticulture sector can considerably contribute to the mitigation. Mitigation is referred to the process in which the emissions of greenhouse gases are either reduced or sequestered. The improved crop management practices can considerably reduce the emission of greenhouse gasses due to reduced dependence on energy needs and intensification of perennial horticultural crops will help in sequestering carbon dioxide from the atmosphere.
Carbon Sequestration Potential
Mitigation efforts through carbon sequestration help to reduce the adverse impacts of climate change. The information about carbon sequestration potential of fruit trees is scanty though they contribute significantly. In a study using PROCOMAP model at HSC, Bangalore, estimated the mitigation potential of farm forestry fruit orchard block planting with 75% of area proposed under Mangifera indica, Tamarindus indica, Achras sapota, Artocarpus, neem and guava. A very important work related to Carbon Sequestration and studying of Carbon pools is going on in Division of Soil Science in SKUAST-J and results are very encouraging. Formulating any new initiatives in the field of horticulture will be much easier once the final results of the project will be coming.
Conclusion
Keeping in view the nature of crop, its sensitivity level and the agro-ecological region, the crop-based adaptation strategies need to be developed, integrating all available options to sustain the productivity. To enhance our preparedness for climate change and to formulate a sound action plan, we need to identify gaps in vital information, prioritize research issues from point of view of farmers, policy-planners, scientists, trade and industry. It is imperative to visualize likely changes which can happen in next 50-100 years. In this regard all the stake holders viz. both the farm universities of the state (SKUAST-J & SKUAST-K), Central Institute of Temperate Horticulture (CITH) and horticulture departments are already working in synergy and there is great hope that with their efforts our state will usher on the path of progress and prosperity in the field of horticulture which is the ultimate aim for all us.
(Authors are Scientists in SKUAST-J)
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