Selection of varieties based on when exactly a crop is getting sown is one of the key components in protecting the yield during an abnormal increase in temperature as seen during the recent heat wave in March-April.
Similarly, straw mulching in orchards can help save fruit crops while bathing cows and buffaloes is one of the simple practices farmers can adopt to overcome the adverse impact of climate change, according to a report prepared by scientists of the Indian Council of Agricultural Research (ICAR).
Some select villages in 25 districts of Bihar, Madhya Pradesh, Uttar Pradesh, Maharashtra, Haryana and Punjab are part of risk-prone 151 clusters created by ICAR through its National Innovations in Climate Resilient Agriculture (NICRA) programme across the country, where technologies were demonstrated that helped minimise the negative impacts of heat waves.
Heat wave impact
The heat wave coincided with the grain filling and development stage of wheat resulting in yellowing and shrivelling of the grain and forced maturity— with an average yield losses between 15-25 per cent.
Similarly, high temperatures resulted in moisture stress, sunburn, flower drop and less fruit setting in horticultural crops like kinnow, pomegranate, mango and lemon. Significant impact was also observed in tomato, cole crops and cucurbits.
Besides, loss of appetite and higher body temperature in milch animals led to a reduction of milk yield up to 15 per cent and a drop in egg production as well as increased broiler mortality was also reported, according to a report titled “Heat Wave 2022: Causes, impacts and way forward for Indian Agriculture” authored by Santanu Kumar Bal, JVNS Prasad and Vinod Kumar Singh of Central Research Institute for Dryland Agriculture.
Ways to solve the problem
Timely sowing and adoption of heat-tolerant varieties PBW03, DBW187 and DBW222 along with a spray of Potassium Nitrate at 0.5 per cent at boot leaf and anthesis stages minimised yield loss in the two clusters in Punjab to only 3-5 per cent of normal productivity in wheat.
Technologies such as mulching in sugarcane, ridge and furrow conserved the soil moisture and minimised the stress, the report said.
Heat tolerant wheat varieties DBW173, Raj4120 and Raj4079 contributed to containing yield loss by 5-6 per cent in the clusters of Baghpat, Jhansi, Hamirpur, Chitrakoot, Pratapgarh, Kaushambi, Bahraich, Gonda, Maharajganj, Gorakhpur, Kushinagar and Sonbhadra districts in Uttar Pradesh, where maximum temperatures were higher by 3-4 degrees over the normal temperature in the second fortnight of March 2022.
Timing and sowing
“If the monsoon is delayed, farmers should adopt short-duration paddy to make sure timely sowing of wheat. Else, they need to select those late wheat varieties in case there is a delay in its sowing due to late harvesting of paddy. Even crop should also be selected based on sowing time not necessarily sticking to a particular crop even though normal sowing window for it is over,” said Singh, one of the authors of the report.
He highlighted how zero-till sowing of wheat ensured timely sowing — immediately after Kharif rice — in flood-prone Gonda and Kushinagar districts in Uttar Pradesh and helped farmers to minimise yield loss.
Heat tolerant and late sown variety of chickpea RVG202 and timely sowing of mustard variety Pusa Bold also escaped the heat stress at maturity in the selected clusters of Madhya Pradesh, according to the report.
During March-April, Maharashtra’s Jalna had 39.6-42.8 degrees temperature and Nandurbar had 41.5-43.0 degrees, which was higher by 4 degrees compared to year-ago. The sudden increase in temperature had impacted horticultural crops.
Other methods to adopt
In the clusters where the NICRA project is getting implemented, resilient technologies such as straw mulching in orchards significantly reduced the impact of heat stress and also minimised water usage. Plastic mulching with frequent irrigations with drip helped in reducing the heat injury to fruit and vegetables.
There was no yield loss. Scientists had also guided farmers to cover fruit trees with shade nets and a cotton cloth to reduce sun scalding and scorching of both leaves and stems. It also helped avoid sunburn on fruits.
Providing shade, water bathing to animals, and feeding with green fodder, concentrates and mineral mixture at 50-70 gms per day helped reduce the impact of heat stress on cows and buffaloes and minimised the milk yield loss in the selected clusters. In villages where electricity was not an issue, farmers used foggers, fans and coolers as it helped maintain proper ventilation and air circulation in the animal sheds.
More heat waves predicted
Unlike the earlier heat waves, the extreme heat during 2022 was widespread, covering several parts of the country. It is predicted that extreme events like this are going to occur more frequently and severely in the years to come due to climate change.
“There is a need to popularise and scale these technologies by way of integrating them into the ongoing development programmes. In addition, strengthening the weather forecasts and agro-advisory services can help farmers taking informed decisions. Such efforts will go a long way in enhancing the resilience of various sectors of Indian agriculture to climatic extremes,” said Singh.