Climate Change and Horticulture: An Indian Perspective
DEBASHIS MANDAL' and R. C. LALDUHSANGI
Department of Horticulture, Aromatic and Medicinal Plants, Mizoram University, Aizawl 796004, Mizoram, India
Climate change and global wanning are the greatest concerns of contemporary time. Due to its impact, commercial cultivation of horticultural crops like fruits, vegetables, flowers and ornamentals, spices and plantation crops, and medicinal plants will perfonn poorly. On one hand melting ice of Himalayas will impact the chilling requirement of temperate crops; on the other hand extremes of temperature will be vulnerable for crop cultivation in open field condition. Besides, pollination will also be hampered because of its effect on pollinators and thus will have significant impact of fruit set and yield. Flowering, crop growth and development, pest and disease infestation will also be influenced due to changing climate. Hence, a sustainable approach is needed to address and mitigate the problem. Conservation, use of renewable energy, reforestation, cultivation of location specific crops suitable in changed climate, resistant and tolerant crops to biotic and abiotic stresses; and hi-tech horticulture involving green houses, shade nets, fertigation, and so on will be crucial for having climate resilient horticulture. Breeding and biotechnological approach for evolving more suitable varieties for stress situations should definitely have to be a thrust area for research.
Global horticulture has numerous challenges and opportunities in present day condition. Climate change indeed is a new challenge as faced by horticulturists worldwide. Climate change is undoubtedly one of the serious issues today. Its impact has become a major concern on the global level because it affects every forms of life. Most importantly, it has direct influence on agriculture and horticulture crops. It has become a serious issue which is discussed more frequently globally. The year 2015 was the hottest year yet recorded which crossed the average temperature across global land and ocean surface, 1.62Т (0.90 C) above the 20th century average, the same year when United Nations Climate Change Conference also known as COP 21 or CMP 11 was held in Paris. Eveiy nation is facing this problem and hence highly commits them in combating this environmental issue.
India is bestowed with different soil and climatic conditions under several agroecological regions which provides great scope to grow a wide variety of horticultural crops, that is, fruits, vegetables, flowers, medicinal aromatics plants, spices, plantation crops, and so on. Horticultural crops form the most important component of human diet to meet the demands of vitamins, minerals, fibers, and so on of the body and also to prevent numerous diseases and value to life. Its importance and value in terms of nutrition, income and employment generation, contribution to GDP of the country, and wellness of physical and mental health are well recognized. The rich land of the country including the Northeast Himalayan region is endowed with diversity of nutritious and highly valued fruits, vegetables, medicinal and aromatic plants, spices and rare flowers. The Indian agroecosystem has contributed in the overall prosperity of the country and still offers a huge scope and potential for resource tapping and development.
Climate change may be defined as the weather changing in a certain manner during the course of the year which includes temperature, atmospheric humidity, rainfall and wind, and so on. Prediction is made to have an increase in average air temperature between 1.4°C to 5.8°C and also to have increase in atmospheric CO, concentration and difference in rainfall pattern (Houghton et al., 2001). It was further reported that climate change is impacting four major contributors to economy, that is, agriculture, water, ecosystems and biodiversity, and health in major climate sensitive regions like Himalayas, Western Ghats, Coastal areas, and Northeast region (Datta, 2013). Global climate change, water scarcity, soil and water pollution, and urbanization are the add-on problems. In one hand temperature is increasing with deceasing rainfall and thus causing scarcity in irrigation water and enhanced evapotranspiration which leads to severe crop water stress conditions (Datta, 2013).
The world average temperature of the Earth’s surface has been increasing for the past 100 years. In simple words, climate change is the change in climate for an uncomparable and infinite time. It has its huge impact directly or indirectly on all forms of life. It can lead to an erratic or unpredictable rainfall pattern, drying up of local lakes and springs, migration of species to higher elevation, change in the period of sowing and harvesting plants, vulnerability and rapid extinctions of flora and fauna. Ozone depletion is one of the major causes of global warming. Major greenhouse gases like carbon dioxide, methane, nitrous oxide, and so on are increasing in the atmosphere through industrial processes, deforestation, burning of fossil fuels, and land degradation.
India, like any other country also felt the impact of climate change tremendously, mainly because of its developing urbanization and agriculture-based economy. Developing countries are more vulnerable to such climate change owing to factors like less technological advancement, lack of resources to mitigate the adversities on agriculture, and so on. Moreover, a greater dependence on agriculture for livelihood of larger proportion of population can further aggravate the situation (Nath and Behera, 2011). India which ranked second in the production of wheat, rice, and sorghum in 2014 was adversely affected due to climate change and also witnessed loss of production in mustard, tomatoes, onions, vegetables, and food crops. As per the recent IPCC report, projection was made to have 10-40% loss in crop production due global warming in India by 2080-2100 (Chadha, 2015).
EFFECT OF CLIMATE CHANGE ON FRUITS
The extreme weather events of hot and cold wave conditions have been reported to cause considerable damage to many fruits. Temperature has a big influence on fruit growth, a large number of fruits crops production tuning will change due to rise in temperature like mango, citrus, banana, and guava crops will develop more rapidly and mature earlier due to rise in temperature (Malhotra, 2017). Strawberries will produce more runners at the expense of fruits (Datta, 2013). Leaf scorching and twig dying are common symptoms of heat stroke in bearing and nonbearing mango plants (Raj an et al., 2011). Elevated temperature with moisture deficit cause cracking and sun burning in apple (Rai et al., 2015) and increase in high temperature during the maturity stage will cause cracking in litclii (Kumar and Kumar, 2007). Diy spell during flower emergence and fruit sheds can reduce the crop duration of banana (Chadha, 2015). Pest and diseases prevalence, for example, fruit fly infestation in guava increased due to hot and humid weather conditions (Malhotra, 2017). The crop likes peach, plum, which require low chilling temperature are also showing sign of decline in productivity (Hazarika, 2015). Erratic rainfall coupled with increasing temperature, less chilling hours is affecting the hill agriculture and food security (Datta, 2013). Apple faced poor fruit set, decrease in productivity when temperature drastically reduced along with rains during end of April. Besides, occurrence of high temperature caused 15 days early flowering in apple. Frost in winter and severe dry heat in summer resulted in poor fruit growth and cracking in litchi. High temperature and high velocity wind during fruit development caused heavy fiuit drop in guava. In citrus increase in 1-2°C temperature beyond 25-30°C promotes vegetative flushes instead of flowers, while untimed winter rain affects flower initiation and increase Psylla incidence in citrus (Malhotra, 2017). Low temperature (4-1ГС), high humidity (80%), and cloudy weather during the month of January caused delayed panicle emergence in mango. Strong wind and cyclone during mango fruit season reduced yield by shedding of fruits and also affects the fruit size and quality (Chadha, 2015).
EFFECT OF CLIMATE CHANGE ON VEGETABLE
India is the second largest producer of vegetable in the world. Environmental stress is the major cause of crop losses worldwide reducing average yield for most of the major crops by more than 50% (Bray et al., 2000). Vegetables being succulent are generally sensitive to environmental extremes and high temperature, limited and excess moisture stresses are the major causes of loss in yields and causes reduction of marketable grade of tomato, potato, and so on (Malhotra, 2017). Most of the vegetable crops are highly sensitive to flooding and genetic variation with respect to its characters. Many vegetable crops namely tomato, watermelon, potato, soybeans, peas, carrot, turnip, and so on are more likely to be damaged by air pollution. Vegetable yields can be reduced by 5-15% when ozone concentration reaches to greater than 50 ppb (Narayan, 2009). Flooding caused accumulation of endogenous ethylene and under high temperature caused rapid wilting which damaged tomato plants (Drew, 1979; Kuo et al., 1982). High temperature caused failure of fruit set mediated by bud drop, abnormal flower development, poor pollen production, ovule abortion, poor viability in tomato and pepper (Hazra et al., 2007; Hazarika, 2015; Erickson and Markhart, 2002). Again, water stress in tomatoes when accompanied by high temperature (above 28°C) caused significant (30-45%) flower drop (Rao, 1995). High temperature (above 40°C) impacted yield to onion by poor bulb size (Lawande, 2010; Daymond et al., 1997) and result shortening of crop duration (Wheeler et al., 1996).
Temperature variation had marked influence on growth and development of vegetable crops. Temperature below 17°C resulted with no seed germination in okra while night temperature below 13°C hampered fruit set in tomatoes. High temperature caused premature bolting in cabbage and sturdy roots in carrot and bitterness in lettuce. Very high temperature impacted low tuber formation in potato and lycopene degradation in tomatoes. However, low temperature also marked effect on sex expression of cucumber by providing more female flower, instead in high temperature it was more male flower production (Hazarika, 2015).