A Simplified Heat-Tolerance Evaluation System at the Pollen Development Stage in Rice (Oryzasativa L.).

Area of Science:

• Agricultural Science
• Plant Biology
• Genetics

Background:

• Heat stress during the reproductive stage significantly impacts rice yield due to temperature sensitivity of pollen development.
• Current methods for assessing heat tolerance in rice are hindered by challenges in synchronizing panicle development and precise staging.

Purpose of the Study:

• To establish a reliable system for quantitatively assessing heat tolerance during rice pollen development.
• To identify rice lines and hybrids with differential tolerance to heat stress.

Main Methods:

• Identified near-isogenic rice lines (ZP15 and ZP17) with contrasting seed-setting rates under heat stress.
• Developed a system synchronizing developmental staging to quantitatively assess heat-induced fertility loss.
• Validated the system using known heat-tolerant (N22) and heat-sensitive (Wushansimiao) varieties.

Main Results:

• Differential tolerance to heat stress was observed during the critical pollen developmental window (9-16 days before heading).
• Huanghuazhan and specific self-bred hybrids demonstrated high heat tolerance.
• Yangdao 6 and several other hybrids exhibited significant sensitivity to heat stress.

Conclusions:

• The developed system provides a precise and reproducible framework for evaluating rice heat tolerance during pollen development.
• This tool can accelerate the breeding of heat-resilient rice varieties crucial for food security.
• Identifying tolerant varieties and hybrids is key to adapting rice production to climate change.