Constant theoretical conductance via changes in vessel diameter and number with height growth in Moringa oleifera. (20th July 2019)

• Record Type: Journal Article
• Authors: Echeverría, Alberto; Anfodillo, Tommaso; Soriano, Diana; Rosell, Julieta A; Olson, Mark E
• Editors: Leubner, Gerhard
• Is Part Of: Journal of experimental botany. Volume 70:Number 20(2019)
• Page Start: 5765
• Page End: 5772
• Publication Date: 2019-07-20
• Subjects: Leaf area-stem scaling -- metabolic scaling -- Moringa oleifera -- whole-plant conductance index -- xylem conduit number -- xylem conduit widening; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/erz329
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract : Intricate anatomical adjustments allow plant theoretical hydraulic capacity per unit leaf area to remain constant as trees grow in height. Abstract: As trees grow taller, hydraulic resistance can be expected to increase, causing photosynthetic productivity to decline. Yet leaves maintain productivity over vast height increases; this maintenance of productivity suggests that leaf-specific conductance remains constant as trees grow taller. Here we test the assumption of constant leaf-specific conductance with height growth and document the stem xylem anatomical adjustments involved. We measured the scaling of total leaf area, mean vessel diameter at terminal twigs and at the stem base, and total vessel number in 139 individuals of Moringa oleifera of different heights, and estimated a whole-plant conductance index from these measurements. Whole-plant conductance and total leaf area scaled at the same rate with height. Congruently, whole-plant conductance and total leaf area scaled isometrically. Constant conductance is made possible by intricate adjustments in anatomy, with conduit diameters in terminal twigs becoming wider, lowering per-vessel resistance, with a concomitant decrease in vessel number per unit leaf area with height growth. Selection maintaining constant conductance per unit leaf area with height growth (or at least minimizing drops in conductance) is likely a potent selective pressure shaping plant hydraulics, and crucially involved in the maintenance of photosynthetic productivity per leaf area across the terrestrial landscape.