Location: Water Management and Systems ResearchTitle: Plant hydraulic mechanisms underlie greater productivity under drought in grain crops
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/2020
Publication Date: N/A
Interpretive Summary: n/a
Technical Abstract: Although there has been great interest in plant mechanisms related to crop production under drought, hydraulic mechanisms have rarely been explored. In maize, we find genotypes with the highest yield under drought in the field have the highest maximum hydraulic conductance, and highest maximum diurnal stomatal conductance. These genotypes have large diameter xylem vessels to facilitate this conductance. Interestingly, maize can lose >50% of its conductive capacity each day, resulting from xylem embolization, even under well-watered conditions. However, high yielding genotypes under drought also have greater root flow via root pressure following re-watering. Immediately after stems are cut, there is no root flow from dry plants but after plants are re-watered and given an hour for recovery, there is substantial flow. Measured root pressures in maize can exceed 100 kPa, which would allow the lifting of water to a height of approximately 10 m in a non-transpiring plant. With extremely low nighttime transpiration and plant heights of approximately 2 m in maize, root pressures measured should effectively pressurize the entire vascular system of the plants and dissolve emboli. In sorghum, maximum root flow after re-watering was also higher in droughted plants than well-watered plants, suggesting an actively-regulated mechanism. We suggest hydraulic mechanisms may be key for maintaining growth of developing grain through reversing potentially embolized xylem and allowing for the resumption of carbon fixation.