Location: Water Management Research
Title: C3 versus C4 cavitation resistance and embolism repair under different levels of soil moisture availability Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 26, 2013
Publication Date: June 4, 2013
Citation: Comas, L.H., Young, J.S., Mcelrone, A.J., Wiggans, D.R. 2013. C3 versus C4 cavitation resistance and embolism repair under different levels of soil moisture availability. Meeting Abstract. The 9th International Workshop on Sap Flow; Gent, Belgium; June 4-7, 2013 Technical Abstract: Comparison of maize and sunflower (Helianthus) under deficit irrigation indicates that maize has more conservative water use with lower maximum hydraulic conductance than Helianthus. We observe that maize under deficit irrigation dramatically reduces transpiration while Helianthus maintains high water use, wilts, but readily recovers. To better understand the underlying physiology and to inform irrigation management, we explored the trade-off that maize (C4) has greater cavitation resistance but slower embolism repair than Helianthus (C3). We measured whole plant transpiration (Esap) in the greenhouse with stem heat balance sap flow gauges on fully and deficit irrigated maize and sunflower from the dry down of deficit plants to 40% of fully irrigated, and then during their subsequent recovery. Whole plant transpiration was measured from the same plants with pots enclosed in a plastic bag and weighed on a balance to verify that the Esap measurement error was similar between plant types and treatments (full vs deficit irrigation). Pre-dawn and midday leaf water potential was measured every two to three days on matching sets of plants under fully irrigated and deficit treatments to estimate the hydraulic conductance from Esap. The percentage of embolized vessels and their refilling was quantified with a dye infiltration. Additionally, we directly measured the hydraulic conductance of midday root systems and intact shoots from matching sets of plants under fully irrigated and deficit treatments with a high pressure flow meter. Results indicate that the xylem vessels of maize have a greater resistance to cavitation but those of Helianthus are quicker to refill. Differences in water production functions and water use efficiency between sunflower and maize suggest that deficit irrigation may be a viable option for irrigation conservation in sunflower but less so in maize. In managing deficit irrigation, however, results here suggest that frequent application of deficit irrigation will be required in sunflower to prevent permanent wilting.