A hot summer for Indian chilies
Heat waves
India is recovering from yet another summer marked by extreme heat waves. This follows a worrying trend; there has been a noticeable increase in heat wave days over India in the past decade, with severe Heat waves more extreme, longer and hotter in El-Niño years[1]. This year, a receding El Niño amplified temperatures already rising due to climate change.
The summer of 2024 began on a relatively normal note in the country, contradicting the trend of an early onset of summer heat in recent years. Active western disturbances and wet spells moderated temperatures in the country during February and March, with good growing conditions especially in the wheat belt of Northern India. April, however, brought severe heat to the southern and eastern parts of India, with record-breaking temperatures and heatwave conditions. A temperature of 47.2°C was recorded in Kalaikunda, West Bengal, on 30th April, some 10°C above normal. At the end of May, extreme heat conditions were widespread. The capital, Delhi, with approximately 30 million inhabitants, sweltered under temperatures of close to 50°C.
Figure 1: Temperature anomaly (in K) over South Asia for May 2024, compared to the earlier decade.
Source: ECMWF ERA5 2m temperature.
Chili production is impacted
In the village of Subhanpur, in the Jalna district in Maharashtra, a major state in central India, Pandurang Sheshrav Rajale, a local farmer, tries to keep his green chili plants well-watered in the early morning. The automatic weather station close to his field already shows a temperature of 35oC just an hour after sunrise. During the night, temperatures haven’t dropped below 30oC which made sleeping almost impossible. These conditions have now lasted for weeks with only some reprieve during occasional pre-monsoon rainstorms. The region where Mr. Rajale farms is famous for its chili production because of its large plantations and high output. The fertile soil and generally favorable climate help chili plants grow well, making it an important place for chili farming and supply. Also here, though, farmers are struggling.
Maharashtra has always experienced extreme heat and dry condition during the summer months. Its inland Marathwada and Vidarbha regions are considered heat wave hotspots. Unlike previous years, this years’ summer heat initially affected mainly the coastal regions rather than the region where Mr. Rajale farms. Mumbai, known for its high humidity, recorded its highest temperature at 39.7°C. Then, slowly, the heat shifted inland. Temperatures of around 40°C were observed in during the whole of April and May – high, but not unusual this time of the year. Only in the last week of May the region entered official heatwave conditions, according to the Indian Meteorological Department.
Figure 2: Minimum and Maximum temperature recorded at a local weather station to support farmers with short term weather and cropping advice, in Jalna district, central Maharashtra, during March to May 2024 (source: WOTR automatic weather station), with in shading the historic 5-95% temperature range (source: ECMWF ERA5 2m temperature, https://cds.climate.copernicus.eu.)
Beat the heat with water
Mr. Rajale is one of 25 farmers that grow chili that we interviewed at the end of May. Farmers were keen to share their experiences and reported many detrimental effects on chili crops due to heat stress. Yields start to get affected when temperatures exceed 35 oC to 40 oC, with reduced fruit quality and increased susceptibility to pests and diseases. With high air temperatures, the crop often does not germinate, soil temperatures increase above critical levels and soil borne diseases fester. Symptoms observed this year include wilting, flower drop, growth retardation, burning of leaves due to high temperature, delaying to flowering, reducing the percentage of flower to fruit ratio, drying of seedlings, yellowing of leaves, size reduction of chili fruits. These manifestations collectively impair crop growth and exacerbate the vulnerability of chili plants. Consequently, pest pressure from pests such as thrips, aphids, and whitefly and the chili leaf curl virus intensify, further compromising the health and vigor of the crops. In many cases this year, farmers had to replant seedlings repeatedly, affecting up to 20-25% of fields. Because of reduced growth and poor flowering, the overall yield of chili crops is expected to drop in the region.
In the drylands of central Maharashtra, where summer vegetable cultivation is a cornerstone of agricultural practice, heat stress poses a significant threat to agricultural productivity. We found a unanimous sentiment regarding the increase in heat stress, with the pervasiveness of heat stress over the past two to three years considered unprecedented. It was felt that not only the intensity of heatwaves and extreme temperatures, but also their duration has heightened the risks associated with crop production, making it more difficult for farmers to keep healthy yields and income.
High temperature in and of itself, however, is ultimately not the main problem. The availability of water for irrigation is essential during the dry, hot summer months. Whatever little rain that falls in summer evaporates quickly so regular water application ensures plants have enough moisture to stay healthy. But after an El Niño year with below average rainfall during the monsoon, water levels in wells and canals were low this year. Usually, in the monsoon, water infiltrates into the soil during heavy rainstorms and replenishes groundwater and fills up the wells which should last till the next monsoon season. The 2023 monsoon only brought 80% of the normal precipitation to the region[2] and in August 2023, most areas recorded less than a third of the usual amount. In the midst of the monsoon (also known as kharif) growing season, with plants in full development, farmers were forced to keep the emerging crop alive with irrigation; water that was supposed to be saved for summer. This lack of irrigation water compounded the impact of high temperatures this May. Keeping chili plants well-watered is crucial. During extreme heat, plants lose a lot of water through their leaves and dry soil heats up quickly. Irrigation requires substantial investment in time and resources which is why farmers prefer vegetables which usually fetch a high price. That is, when one has a harvest to sell.
Green chili plants with white plastic mulch in Dhawale, Maharashtra, India
Price volatility
The agricultural sector in semi-arid regions is not only a critical source of food but also a major part of the local economy. The erratic nature of heat stress disrupts traditional sowing patterns, leading to variations in harvest timing. This volatility extends to market dynamics, influencing chili prices due to fluctuations in both quality and quantity of the produce. The chilies that do grow might not be of good quality, with chilies smaller, mis-shaped, or less flavorful. Under stress, the mature green chili turns brown quicker. This affects their market value and can make them less appealing to buyers. Furthermore, burning and delayed fruit set results in a late harvesting, causing the harvested chili to arrive late in the market with farmers exposed to uncertain price fluctuations. The inconsistent supply due to unpredictable harvesting times leads to further price volatility, making it difficult for both producers and buyers to plan accordingly.
Heat also inflates production costs; a diminished crop resilience exacerbates the challenge of pest management, necessitating additional labor and resources. Farmers need to invest more in irrigation, or in heat-tolerant crop varieties, and other adaptive measures. This year, in addition to challenges with crop inputs, farmers met issues such as labor shortages for essential tasks such as spraying, weeding, and input application, and harvesting. Extreme temperatures made it challenging for workers to work efficiently, leading to delays in crucial farming activities. Additionally, the health risks associated with prolonged exposure to high temperatures result in increased absenteeism and higher turnover rates among farm laborers, further exacerbating the labor shortages. Those laborers that did come to work, demanded higher wages.
Reduced crop yields and higher costs translate to lower income for farmers, worsening poverty and food insecurity. Decreased agricultural output can lead to higher food prices, making it difficult for low-income families to afford basic necessities. The impacts of heat stress extend beyond crop yields, affecting the livelihoods of millions of farmers and their communities.
India is the world's largest producer, consumer and exporter of chilies. The chili cultivated in Jalna is primarily a green chili variety, most of which is exported to other countries, especially Bangladesh. This year, Bangladesh is experiencing a surge in chili prices due to heat wave conditions in combination with a seasonal effect of reduce supply at the start of the monsoon, and is likely to import green chilies to stabilize its market. However, the timing and sources of these imports are still uncertain.
Limits to coping
Many farmers in the area boast decades-long experience cultivating chili crops. They innovate and have adopted a range of management practices to mitigate the impact of heat stress on chili production. These strategies include the deployment of shade nets, sprinkler irrigation, field fencing, soil application near the root zone, and timing agricultural activities to coincide with cooler periods of the day. Such measures have shown promise in safeguarding chili crops amidst escalating heat stress and drought conditions.
There are limits to coping, though, and these are often financial. More than 80% of interviewed farmers had adopted plastic mulching for their crops over the years. This reduces evaporation from soil and weeds, and thus irrigation water demand, and – in the case of white plastic - moderates soil temperatures in summer. With mulch, a drop of water lasts longer and grows more crops. But it is expensive and when wells fall dry, and yields drop below critical levels, the cost of plastic mulch becomes a liability. When farmers cannot apply or adhere to a proper irrigation schedule, the risk of seedling burning and unnecessary wilting due to the elevated temperature of the dry root zone increases again.
Farmers indicated that attempting to grow chili crops under heat stress with only 50% of the required irrigation water is highly risky, as the crops are likely to fail at a later stage. They questioned the necessity of taking such a high risk when they know the crops cannot thrive under these conditions. An estimated 25% of farmers who in previous years sowed chili as a cash crop, this year planted for only home consumption or even kept land fallow. Of those who did sow chili crops as per usual in February and March 2024, 80% reported that the crops are not bearing flowers due to factors such as moisture stress, heat stress, and evaporation loss. With little expectation of fully recapturing investments, a quarter has stopped applying the necessary nutrients, crop protection measures, and agronomic practices during the growing season.
Adapting
There is more that can be done. Drip irrigation delivers water directly to the plant roots, reducing water waste and ensuring consistent moisture levels in the soil. Though more expensive than sprinkler irrigation, an income from vegetables like chilies is likely to pay back the investment. Scheduling irrigation, by watering during the early morning or late evening, reduces evaporation losses and helps conserve soil moisture. As with drip irrigation, it requires farmers to have control over their water resources and/or supply. Short-term location specific weather forecasts, e.g., on the possibility of rain in the coming days, which could save an irrigation application or lead to more targeted pesticide or fertilizer application, can further improve crop-water management.
While plastic mulch has its benefits and has become the standard, applying organic mulch helps keep soil moisture, reduce soil temperature, and prevent weed growth. Incorporating compost and other organic materials into the soil can improve soil structure, water retention, and root health. A healthy soil improves a plant's resilience to heat stress. Sowing tall crops such as maize, sorghum, fodder grass around the main field can provide added shading as do trees and tree lines.
Specific measures such as foliar sprays containing calcium, potassium, or silicon can strengthen plant cells and improve heat tolerance while anti-transpirants can reduce water loss from plant leaves, helping to keep hydration during periods of high heat.
All these measures have been piloted, and form part of a farmers’ portfolio of options. But each measure also implies added investments or operational costs which need to be weighed against the expected benefits. In a highly variable climate, these will vary from year to year and with climate change accelerating, historic evidence and experience offers limited guidance. Farmers don’t have unlimited capacity to experiment.
A better insight into medium-term weather conditions, weeks or a month ahead can help farmers make better management decisions. Notoriously difficult, with innovations in AI and weather forecasts, accuracy of prediction at these timescales is likely to increase though usefulness in practice still needs to be assessed. Better and timely information on growing conditions elsewhere, affecting future market conditions and prices, might also help farmers decide whether investments are worth it.
Take-away message
The findings underscore the pressing need for proactive measures to address the combined threat of water and heat stress on chili production. By prioritizing adaptation and innovation, stakeholders can mitigate adverse impacts, ensuring the sustainability and viability of chili cultivation in the face of mounting climatic pressures. As climate change continues to worsen environmental conditions, collaborative efforts among farmers, researchers, and policymakers are imperative to develop resilient agricultural systems capable of withstanding the rigors of a changing and variable climate.
Method: Colleagues from WOTR, a large watershed and livelihood development NGO based in Pune, interviewed 25 farmers, one farmer from each chili-growing village in the Bhokardan block, Jalna district, Maharashtra, India, at the end of May. The aim was to ensure that the sample reflects the conditions within this area where WOTR has been operational for over a decade supporting watershed development initiatives. The analysis of weather conditions was based on the observations of WOTRs automatic weather station network and from data from the European Centre for Medium-Range Weather Forecasts (ECMWF), with its ERA5 dataset providing historic and (near) real time data for a range of climatic indicators.
This story has also been published on WOTR’s website as a blog.
[1] Mahavedh AWS Grid, Govt. of Maharashtra
[2] M. Rajeevan, Rohini. P, S.N. Nair, S. Tirkey and T. Goswami (2023), Heat and Cold Waves in India; India Meteorological Department, Ministry of Earth Sciences, New Delhi