The Periodic Watering Modulating Diurnal Rhythms of Stomatal Conductance

• Applicant: Joao Antonio Siqueira, Ph.D.
• Subject Area: Plant Physiology ; Plant Cultivation, Plant Nutrition, Agricultural Technology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 556450559

Optimizing water use efficiency (WUE) of crops remains a paramount for modern farming practices. Our current comprehension of plant responses to watering predominantly focuses on steady state conditions. However, recent studies conducted in field conditions have unveiled intriguing disparities in the productivity of certain maize (Zea mays) and tomato (Solanum lycopersicum) cultivars when subjected to irrigation during distinct periods of the day, delineating the concept of periodic watering. Despite the acknowledged role of stomatal movements in regulating WUE and plant yield, their specific involvement in orchestrating responses to periodic watering remains unexplored. Hence, elucidating the intricate regulation of stomatal movements in response to both dawn and dusk watering appears to be a promising approach to significantly enhancing WUE in crops. My preliminary results suggest that dusk watering, when compared to dawn, improves WUE of Arabidopsis thaliana plants, whereas genes involved in stomatal closure display the highest level of expression during this time frame. The aim of this research project is understanding the consequences of dawn and dusk watering on stomatal movement regulation through i) Determine the impact of dawn- versus dusk watering on guard cell gene expression, ii) Monitor the ABA responsiveness in single guard cells from plants subjected to periodic watering; iii) Compare the activity and availability of SLAC1 and SLAH3 in dawn and dusk-watered plants. The anticipated outcomes of this project are poised to advance our understanding of the temporal dynamics underlying stomatal responses to fluctuations in water availability. Furthermore, the practical insights obtained from this investigation hold the potential to drive agricultural programmes aimed at optimizing WUE in crops, thus fostering sustainable farming practices

• DFG Programme: WBP Position