Stomatal variability of native warm-season grasses from the Nebraska Sandhills

Abstract

. 2002. Stomatal variability of native warm-season grasses from the Nebraska Sandhills. Can. J. Plant Sci. 82: [349][350][351][352][353][354][355]. Soil moisture deficit is usually the major limiting factor for herbage production in the Sandhills of Nebraska. We examined inter-population and interspecific variability in stomatal characteristics and drought tolerance in sand bluestem (Andropogon hallii Vitman), little bluestem [Schizachyrium scoparium (Michx.) Nash], prairie sandreed [Calamovilfa longifolia (Hook) Scribn.], and switchgrass (Panicum virgatum L.). Ramets were collected during the dormant season across an aridity gradient from east to west (ranging from 560 mm to 340 mm average annual precipitation) in the Sandhills of Nebraska. Plants were grown in individual pots under greenhouse conditions. Once plants were well established, stomatal characteristics were determined and stomatal conductance (g s ) was measured through a dry-down period of no watering. Populations did not differ in stomatal characteristics across the gradient, except for stomatal density on the adaxial leaf surface of prairie sandreed and the abaxial leaf surface of sand bluestem. Leaves of switchgrass and prairie sandreed were amphistomatic (stomata on both leaf surfaces), whereas leaves of little bluestem and sand bluestem were hypostomatic (stomata on the lower leaf surface). In the absence of drought, g s was 17 to 31% higher in little bluestem than in other species. Differences among species in g s were found mainly when watered and disappeared as the dry-down progressed. There was a positive relationship between stomatal density and g s in all species except prairie sandreed. Prairie sandreed maintained 35% of the initial relative water content of its leaves after 17 d of dry-down, compared to 23% for sand bluestem, 14% for switchgrass, and 9% for little bluestem. Variation in stomatal traits within species did not explain ecotypic adaptation to sites with a range of precipitation in the Nebraska Sandhills. . Pour cela, ils ont prélevé des ramets durant la période de dormance selon un gradient d'aridité d'est en ouest (de 560 mm à 340 mm de précipitations annuelles, en moyenne), dans la région à l'étude. Les plantes ont été cultivées en serre dans des pots individuels. Une fois les plants établis, on a déterminé leurs paramètres stomatiques et calculé la conductance stomatique (g s ) en interrompant les arrosages un certain temps. Les paramètres stomatiques des plantes ne varient pas avec le gradient, hormis la densité des stomates sur la face ventrale des feuilles d'A. hallii. Les feuilles du panic raide et de C. longifolia sont amphistomatiques (stomates sur les deux faces) alors que celles des deux autres espèces sont hypostomatiques (stomates sur la face ventrale). Quand il n'y a pas sécheresse, la g s du schizachyrium à balais dépasse celle des autres espèces de 17 à 31 %. La variation de la g s d'une espèce à l'autre se manifeste surtout au moment de l'arrosage et disparaît dès que la sécheresse s'installe. La densité d...

On the relationship between stomatal characters and atmospheric CO2

“…Furthermore, signaling of light and CO 2 for stomatal development has been explored and appears similar [ Lake et al , 2001]. Likewise, exposure to drought during leaf development reduces SD [ Ciha and Brun , 1975; Awada et al , 2002], and, in altitudinal gradients where atmospheric CO 2 decreases, SD is determined by precipitation rather than CO 2 concentration [ Körner et al , 1986]. Therefore, environmental factors other than CO 2 concentration may be stronger determinants of stomatal characters in natural settings.…”

Ecophysiology of Two Native Invasive Woody Species and Two Dominant Warm‐Season Grasses in the Semiarid Grasslands of the Nebraska Sandhills

“…Thus, WUE and NUE at the leaf level were inversely correlated for these two grasses (Tjoelker et al 2005). Physiological differences among C 4 grass species are also attributed to stomatal distribution and morphology (Redmann 1985;Salisbury and Ross 1985;Awada et al 2002) and to photosynthetic subtype (Long 1999). Panicum virgatum and S. scoparium differ for these traits as well.…”

“…Panicum virgatum and S. scoparium differ for these traits as well. These ecophysiological differences among grasses contribute to the spatial distribution of C 4 plants in the semiarid grasslands of the Nebraska Sandhills (Schacht et al 2000;Awada et al 2002). Summer drought, a usual phenomenon, forced both grasses into dormancy late in the growing season.…”

Contrasting physiological responsiveness of establishing trees and a C4 grass to rainfall events, intensified summer drought, and warming in oak savanna

“…We hypothesize that these contrasting functional types may uniquely affect the response of savanna dominants to climate warming and intensified summer drought (Reich et al, 2001a;Tjoelker et al, 2005). All three of the dominant savanna species possess a high degree of drought resistance (Bifoss, 1947;Pallardy & Rhoads, 1993;Awada et al, 2002;Kikuta et al, 2003), but their potential for physiological recovery following transient precipitation events during prolonged seasonal drought is largely unknown. The ability to respond to intermittent rainfall events may be especially important for survival, growth, and competitive ability during tree seedling establishment.…”