Short-term heat stress during flowering results in a decline in Canola seed productivity

Oilseed rape (Brassica napus) or Canola is an important oilseed crop produced and consumed globally. The predicted increase in the frequency of high-temperature events associated with climate change poses a threat to Canola productivity. In the present work, we report the impact of short-term heat stress on the reproductive fitness and yield components of Canola. Short heat stress episodes, especially above 36°C, resulted in diminished reproductive fitness due to reduced pollen viability and germinability. Heat stress exposure led to asynchronous male and female development and suppressed pollen development in developing buds. As the temperature increased above 32°C, the seed production decreased significantly. Temperatures beyond 38°C resulted in >50% reduction in total seed production and seed weight. Short-term heat stress also reduced yield components, seed vigour and post-harvest seed characteristics. Biochemical investigations of the seeds harvested from heat-stressed (40°C for 12 hr) plants showed decreased oil content along with a variable fatty acid composition. The omega-6/omega-3 ratios increased in response to heat stress indicated a possible decline in oil nutritional quality. Understanding the impact of short heat stress episodes can provide efficient heat tolerance screening tools and pave the way for developing heat stress-tolerant B. napus varieties.