Water Deficit at Vegetative Stage Induces Tolerance to High Temperature during Anthesis in Rice.

Area of Science:

• Plant Science
• Agronomy
• Stress Physiology

Background:

• Crop yields are impacted by various biotic and abiotic stressors.
• Plants can develop cross-tolerance to multiple stresses, a phenomenon potentially influenced by rising atmospheric carbon dioxide concentrations ([CO2]).
• Priming involves pre-exposing plants to mild stress to enhance their resilience and yield under subsequent stress conditions.

Purpose of the Study:

• To investigate if water deficit priming during the vegetative stage induces heat stress tolerance in rice at anthesis.
• To assess the influence of elevated atmospheric carbon dioxide (e[CO2]) on this priming effect and subsequent heat stress tolerance.

Main Methods:

• A completely randomized design with a factorial arrangement was used.
• Treatments included water deficit (drought stress) at the four-leaf stage, heat stress at anthesis, and priming with water deficit followed by heat stress.
• Experiments were conducted under ambient [CO2] (a[CO2]) and elevated [CO2] (e[CO2]) conditions (700 μmol mol⁻¹).

Main Results:

• Priming with water deficit significantly increased rice yield and the number of panicles per plant.
• Primed plants exhibited upregulation of heat shock protein genes (OsHSP16.9A, OsHSP70.1, OsHSP70.6), indicating induced tolerance.
• Elevated CO2 (e[CO2]) influenced growth parameters but did not alter the beneficial priming effect.

Conclusions:

• Water deficit applied during the vegetative stage effectively reduces the negative impacts of heat stress during the reproductive stage in rice.
• This priming strategy shows promise for improving rice cultivation under heat stress conditions.
• Further field trials are recommended to validate the efficacy of water deficit priming for mitigating heat stress in rice.