Assessing Heat Tolerance in Creeping Bentgrass Lines Based on Physiological Responses

Area of Science:

• Plant Science
• Agronomy
• Physiology

Background:

• Heat stress poses a significant threat to cool-season turfgrasses like creeping bentgrass (Agrostis stolonifera L.).
• Understanding the physiological and biochemical mechanisms of thermotolerance is crucial for developing heat-resilient cultivars.
• Current knowledge on creeping bentgrass thermotolerance mechanisms is limited and lacks systematic investigation.

Purpose of the Study:

• To evaluate heat tolerance in experimental creeping bentgrass lines and cultivars.
• To identify key physiological and biochemical traits associated with enhanced thermotolerance.
• To assess the utility of OJIP fluorescence as a tool for screening heat tolerance.

Main Methods:

• Ten creeping bentgrass lines were subjected to controlled heat stress (38/33 °C day/night) versus optimal conditions (20/15 °C day/night) for 35 days.
• Principal component and cluster analyses were employed to rank stress performance and group lines by tolerance.
• OJIP fluorescence measurements were used to analyze photosynthetic efficiency under heat stress.

Main Results:

• Lines S11 729-10 and BTC032 exhibited superior thermotolerance, maintaining cell membrane stability and protein metabolism while minimizing oxidative damage.
• Heat-sensitive lines included Crenshaw, S11 675-02, and Pure Eclipse.
• OJIP fluorescence analysis indicated that energy trapping, dissipation, and electron transport to PQ were more sensitive to heat than transport to PSI acceptors.

Conclusions:

• Variability in heat tolerance mechanisms exists within creeping bentgrass germplasm.
• OJIP fluorescence is a valuable tool for dissecting photosynthetic responses to heat stress and identifying critical limiting steps.
• These findings can guide the development of new creeping bentgrass cultivars with enhanced thermotolerance for improved turf performance.