Upcoming heat wave may bake wheat at crucial stage

LAHORE: Forthcoming heat wave, expected from March 10-11, poses serious threat to the otherwise super-healthy standing wheat crop, The News has learned.

According to an official estimate, if a heat wave exceeding 30-32C was somehow delayed till the third week of March, Punjab looks very much on course to harvest a bumper crop close to 21 million tonnes. Apart from the heat wave, gusty winds and hailstorm have also being described as potential threats to the crop at the crucial stage of grain formation.

Mubashar Naeem, a progression farmer from Layyah was confident about harvesting a good crop this year. “So far so good for the standing wheat crop despite shortage of fertiliser and high cost of inputs obstructing their use,” he said, and added that several timely spells of rains in last 4-5 weeks have tremendously changed the outlook for production.

Rao Afsar, a small-scale grower from Rajanpur, said cool weather during the early stage of crop has set the stage for good wheat output this year. However, he cautioned that weather should be warmer to some extent during maturity stage otherwise grain shrivelling due to forced maturity would ruin the farmer’s hard work.

Ejaz Rao, a progressive farmer hailing from Bahawalpur, said windy conditions and reported hailstorm have caused some sporadic damage to the crop in the south-western belt of the province. “However, given the isolated nature of the calamity causing lodging of plants, it may not affect the output significantly.”

Rao was of the view that wheat crop was presently in ideal conditions despite several challenges. Expressing satisfaction with the way things were progressing at the grain formation stage, he said a good crop is direly needed for a country like Pakistan in the aftermath of the Russia-Ukraine war.

“We need to produce close to 28 million tonnes of wheat for meeting annual requirements.” Weather conditions have been ideal for raising a bumper crop. However, the next couple of weeks were crucial for harvesting a good crop having higher per acre yield.

Citing a research finding, Rao said photosynthesis was one of the most sensitive processes to high temperature in wheat.

“Photosynthetic rates involving growth of plant exhibit a sharp decline when wheat crop is exposed to high temperature stress during reproductive phase.” Optimum temperature for photosynthesis has a broad range of 20 to 30C in wheat. Fortunately, wheat crop in the province got extended generous days of such ideal temperatures this year.

It should be noted that wheat crop was highly sensitive to hot weather conditions. According to a study, temperature stress is considered a major environmental factor that limits yield in wheat.

Every 1C increase above a mean temperature of 30C before March 30 potentially decreases wheat yield by around 10 percent. The main reason of hardening and maturity of grain has been attributed to rapid declining in photosynthesis rate at temperatures above 30C, which is indicated by changing colour of crop from green to pale.