The preceding decades have witnessed a gradual shift in normal weather events, alarmingly affecting rainfall intensity, pattern, frequency and heat events. Across the world, climate patterns are influenced by various natural phenomena, including El Niño and La Nina.
Both originate in the Pacific Ocean, which covers nearly 46 per cent of the earth’s water surface and 32 per cent of its total surface area. It has far-reaching consequences on global weather patterns, including India’s monsoon season. El Niño weakens moisture-laden winds, causes erratic, deficit rainfall across the Indian subcontinent and occurs every two to seven years, lasting for several months.
On the contrary, La Niña results in normal to above-normal rainfall in India during the southwest monsoon season and below-normal temperatures during the winter. High pressure (cool air) over the eastern Pacific and low pressure (warm air) over the Indian Ocean push moisture-laden winds toward India. Under normal conditions, the southwest monsoon accounts for about 75 per cent of the country’s annual rainfall. WorldNews Section
The India Meteorological Department (IMD) has indicated a deficient or below-normal monsoon this year. Deficient rainfall causes a drop in crop yields and drives up food inflation. Severe heat waves and droughts frequently result in heat-related illnesses and negatively impact the rural economy.
Apple and other fruit-growing regions of Himachal, Uttarakhand and Jammu and Kashmir experience elevated heat stress, reduced soil moisture, disrupted chilling periods, threatening both fruit productivity and the quality of fruit production.
El Niño years often bring a warmer, drier winter and pre-monsoon heat waves. Most commercial apple varieties require between 800 to 1,200 chilling hours (below 7.2°C) depending on the variety/cultivar. High temperatures impact these chill units, causing irregular flowering and poor fruit set and yield. Insufficient rain during critical fruit growth stages drastically reduce the fruit size and quality.
Warmer climate and erratic humidity create favourable environment for the proliferation of pests such as San Jose scale, red mite, apple scab, alternaria leaf spot/blight, tissue borers and woolly aphids etc.
El Niño often increases the intensity of erratic heavy rain, causing flashfloods and soil erosion in mountainous regions. It is imperative to follow practices and techniques that help minimise the adverse effect on plant growth and fruit harvest.
Go for climate resilient cultivars
In apple and other temperate fruit growing zones experiencing shifting climate patterns, farmers should be encouraged to introduce climate resilient and short-duration high colour apple cultivars like Galas, Early Red One, Zouk-55 etc., and early season fruit crops like cherries, blueberries, nectarines, apricots, pears, walnuts, pomegranates, persimmons, strawberries, Jackfruit, guava, dragon fruit, kinnow, avocado, litchi etc., to mitigate climate impact.
Fruit production decline during years with moderate El Niño events. Farmers should be cautioned about a judicious use of irrigation water, modifying cultural practices and need-based application of fertilizers and pesticides is warranted to ensure the optimal use of available water. Wherever the monsoon rainfall decreases, appropriate moisture conservation practices become a necessity.
Good practices
Grass growing in the basin area of fruit trees should be cut regularly to prevent water accumulation. Bury the grass along the outer drip line and cover it with 5 cm of soil. Covering the tree basin area with grass or jute sacks or reflective polythene sheets as mulching offers innumerable benefits such as minimal evapotranspiration, soil temperature regulation, moisture and soil fertility preservation, least nutrient losses, etc.
Reflective mulches improve light exposure, air circulation, help develop desirable fruit colour and reduce the incidence of premature leaf-fall, scab, Alternaria disease and woolly aphid, etc. When applied correctly, mulching significantly enhances orchard productivity and sustainability. Practising regular summer pruning until September enhances the fruit size, colour, insect and disease incidence during the current year, besides ensuring crop harvest next year.
Planting fruit crops along natural contour lines is a general practice in the mountains. As a result, rainwater flows down the slope, causing erosion, loss of top soil and precious nutrients. By raising the tree basin area slope gently from the valley side to the hillside helps check water flow and allow it to be absorbed into the basin area while keeping the soil intact in place. Adding adequate quantities of well-rotten FYM or compost to the soil during the winter improves the soil sponginess to store water and nutrients.
Harvest rainwater
Harvest surface rainwater and erratic downpours by digging 90 cm to 120 cm saucer-shaped storage spaces along contours in the mid-area between tree rows in the orchard. This helps store rainwater for a considerable period, facilitate the recharging of soil moisture levels, checks overflow, soil erosion, nutrient depletion, organic matter and supports mitigate water stress.
Depending upon the fruit tree canopy, completely avoid the tillage of the basin in the 1.5 metre radius from the tree trunk to check water accumulation around the tree trunk and main roots. Since the orchard soil plays a vital role in moisture conservation, only the outer one-metre wide basin within the tree canopy, where organic manure and fertilisers are applied, should be tilled.
In addition, micro-irrigation, the rejuvenation of neglected water sources, wherever available, and the adoption of climate-resilient varieties help maintain adequate soil moisture and improve water-use efficiency during prolonged dry spells.
