Periodic Reporting for period 2 - AgroPHYS (Understanding how plants overcome drought by controlling stomatal function: applicability and impacts on agriculture)
Berichtszeitraum: 2019-08-01 bis 2020-07-31
The AgroPHYS project aims to combine three important fields of research (diagram attached) to deal with this urgent need: a fundamental understanding of the physiological mechanisms of plant response to drought, the use of plant sensors to monitor these responses in real-time, and the implementation of physiological-based models to predicting the impacts of global change on plants and providing new hypotheses to be tested.
The conclusions of the action can be summarized as: (1) the use of the optical technique to visualize in vivo the air blockage formation within the vascular system as olive seedlings dehydrated, allowed us to demonstrate that roots were the most resistant organs to hydraulic dysfunction; (2) the results obtained from this optical technique, which is easy to use and low-cost, agree with most common, hydraulic techniques and with highly-resolution, synchrotron-based techniques; (3) stomatal opening limitations appear to be related with a decrease in soil-root hydraulic conductance under moderate levels of water stress in olive; (4) leaf abscisic acid production is crucial for protecting vessels from air blockage formation by playing a key role on triggering stomatal closure; and (5) with a combination of mechanistic models and leaf turgor pressure sensors, the automatic and continuous monitoring of stomatal conductance is possible in fruit tree species, which will improve the water used by these fruit orchards.
Directly related to AgroPHYS, we expanded our knowledge on how hydraulic traits can be decisive for protecting plants against drought negative effects by working with different olive genotypes. Moreover, the application perspective of AgroPHYS was also addressed by developing robust, physiologically based tools for irrigation management, demonstrating that combining the three main fields of research of AgroPHYS is not only possible but fundamental for progressing on optimizing water use in agriculture.
In addition to these direct outcomes from AgroPHYS, and thanks to the participation in Synchrotron-based campaigns, we demonstrated that the optical technique was equally effective as hydraulic and micro-tomography techniques for measuring hydraulic resistance thresholds of water stress.
During the entire Incoming Phase, experiments were mainly focused on applying the new plant physiological knowledge acquired during the Outgoing Phase on the experimental orchard ‘La Hampa’ from the IRNAS-CSIC. Six fruit tree species were physiologically, extensively characterized, and monitored with meteorological, soil, and plant sensors.
As an overview of the overall results of AgroPHYS we can say that (1) knowing the resistance to water stress of agricultural species is pivotal under a global change context; (2) however, these levels of water stress should not be reached in fruit tree orchards and, in fact, plants avoid that by closing stomata; (3) limitations on productivity derived from this stomatal closure appear to be related with the belowground capacity to water uptake; and (4) we thus demonstrated that stomatal conductance should be our target to monitor water stress in fruit orchards.
Exploitation and dissemination of these results have been addressed by presenting them in several Xylem International Meetings, in seminars in both University of Tasmania and Researcher Centres in Spain, starting a collaboration with soil scientist at the University of Bayreuth (Germany), and publishing several papers in highly ranked journals, giving extra support to our conclusions.