Genotypic variability in vulnerability of leaf xylem to cavitation in water-stressed and well-irrigated sugarcane

• Published in: Plant physiology (Bethesda) 1992-10, Vol.100 (2), p.1020-1028
• Main Authors: Neufeld, H.S, Grantz, D.A, Meinzer, F.C, Goldstein, G, Crisosto, G.M, Crisosto, C
• Format: Article
• Language: English
• Subjects: Acoustic emission; Biological and medical sciences; Cavitation flow; Dehydration; Embolisms; Environmental and Stress Physiology; ESTRES DE SEQUIA; FEUILLE; Fundamental and applied biological sciences. Psychology; GENOTIPOS; GENOTYPE; HOJAS; Hydraulic conductivity; Hydraulics; IRRIGATION; Leaves; Plant physiology and development; Plants; PROCESAMIENTO; PROPIEDADES FISICO-QUIMICAS; PROPRIETE PHYSICOCHIMIQUE; RELACIONES PLANTA AGUA; RELATION PLANTE EAU; RIEGO; SACCHARUM; STRESS DU A LA SECHERESSE; Sugar cane; TRAITEMENT; Water and solutes. Absorption, translocation and permeability; XILEMA; Xylem; XYLEME
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.100.2.1020

Genotypic variability in vulnerability of leaf xylem to waterstress-induced cavitation was determined in four sugarcane (Saccharum sp.) clones using detached leaf segments in a hydraulic conductivity apparatus. Vulnerability curves were constructed by plotting the percentage of maximum conductivity versus leaf water potential and fitting curves using a Weibull function. The leaf water potential at which each clone lost 10, 50, and 80% of maximum conductivity was determined. Maximum conductivity per unit of leaf width was positively associated with metaxylem vessel diameter. The commercial clone H65-7052 exhibited the highest and the nondomesticated S. spontaneum exhibited the lowest conductivity. All four clones lost substantial conductivity at values of leaf water potential less negative than -1.4 MPa, but H65-7052 was able to maintain 50% conductivity to lower leaf water potential than the other clones. S. spontaneum sustained the most negative leaf water potential (-1.99 MPa) before reaching the 80% conductivity loss point. Clone H69-8235 was consistently the most vulnerable to initial loss of conductivity. These vulnerability functions were used in conjunction with field measurements of leaf water potential to estimate diurnal losses in leaf hydraulic conductivity under irrigated and droughted conditions. H69-8235 lost up to 50% of its conductivity during the day, even when well irrigated, and more than 80% when subjected to drought. The other clones exhibited lower conductivity losses. These losses are apparently reversed overnight by root pressure. Despite their close genetic relationships, these clones exhibited large differences in conductivity, in the vulnerability of their xylem to cavitation, and in gas exchange behavior. The potential for altering water relations by selecting for particular hydraulic characteristics is discussed