Carbon isotope discrimination, gas exchange, and growth of sugarcane cultivars under salinity

• Published in: Plant physiology (Bethesda) Vol. 104; no. 2; pp. 521 - 526
• Main Authors: Meinzer, F.C, Plaut, Z, Saliendra, N.Z
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.02.1994
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; C4 plants; Carbon dioxide; Carbon isotopes; CARBONE; CARBONO; ECHANGE D'ION; ECHANGE GAZEUX; Environmental and Stress Physiology; FOTOSINTESIS; Fundamental and applied biological sciences. Psychology; Genetic variation; Genotypes; HIBRIDOS; HYBRIDE; INDICE DE CRECIMIENTO; INTERCAMBIO DE GASES; INTERCAMBIO IONICO; ISOTOPE; ISOTOPOS; PHOTOSYNTHESE; Photosynthesis; Plant physiology and development; Plants; SACCHARUM; SALINIDAD; SALINITE; Salinity; Soil salinity; Sugar cane; TALLO; TAUX DE CROISSANCE; TIGE; VARIACION GENETICA; VARIATION GENETIQUE; VARIEDADES; VARIETE; Water and solutes. Absorption, translocation and permeability; Saccharum; Monocotyledones; Growth; Carbon dioxide; Stomatal conductance; Isotopic composition; Stress; Salinity; Resistance; Gramineae; Angiospermae; Spermatophyta; Gas exchange; Greenhouse study; Cultivar; Sodium Chlorides
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.104.2.521

Physiological features associated with differential resistance to salinity were evaluated in two sugarcane (Saccharum spp. hybrid) cultivars over an 8-week period during which greenhouse-grown plants were drip-irrigated with water or with NaCl solutions of 2, 4, 8, or 12 decisiemens (dS) m-1 electrical conductivity (EC). The CO2 assimilation rate (A), stomatal conductance (g), and shoot growth rate (SGR) began to decline as EC of the irrigation solution increased above 2 dS m-1. A, g, and SGR of a salinity-resistant cultivar (H69-8235) were consistently higher than those of a salinity-susceptible cultivar (H65-7052) at all levels of salinity and declined less sharply with increasing salinity. Carbon isotope discrimination in tissue obtained from the uppermost fully expanded leaf increased with salinity and with time elapsed from the beginning of the experiment, but carbon isotope discrimination was consistently lower in the resistant than in the susceptible cultivar at all levels of salinity. Gas-exchange measurements suggested that variation in carbon isotope discrimination was attributable largely to variation in bundle sheath leakiness. Salinity-induced increases in bundle sheath leakiness to CO2 appeared to be caused by a reduction in C3 pathway activity relative to C4 pathway activity rather than by physical changes in the permeability of the bundle sheath to CO2. A strong correlation between carbon isotope discrimination and A, g, and SGR permitted these to be predicted from carbon isotope discrimination regardless of the cultivar and salinity level. Carbon isotope discrimination thus provided an integrated measure of several components of physiological performance and response