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Carbon Isotope Discrimination: Relationship to Yield, Gas Exchange, and Water‐Use Efficiency in Field‐Grown Crested Wheatgrass
Author(s) -
Read John J.,
Johnson Douglas A.,
Asay Kay H.,
Tieszen Larry L.
Publication year - 1992
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1992.0011183x003200010035x
Subject(s) - water use efficiency , biology , transpiration , agronomy , shoot , soil water , dry weight , horticulture , botany , photosynthesis , irrigation , ecology
In previous greenhouse experiments, stable C isotope discrimination (Δ) was negatively associated with water‐use efficiency (WUE) in crested wheatgrass [ Agropyron desertorum (Fischer ex Link) Schultes]. We conducted two field experiments to evaluate associations among Δ, leaf WUE, and shoot WUE (dry weight change/plant transpiration) in clones of crested wheatgrass selected on the basis of low, medium, or high Δ. The first experiment involved leaves of five clones from each Δ class, with WUE i and Δ determined at two field sites. Mean Δ values are always less for low‐Δ than high‐Δ clones, but did not differ significantly between medium‐Δ and high‐Δ clones. Negative correlations were obtained between Δ and WUE i at both the rainfed ( r = −0.77**, df = 13, p < 0.01) and irrigated ( r = −0.87**, df = 13) sites; however, WUE i of low‐Δ clones exceeded that of high‐Δ clones only under rainfed conditions. The second experiment compared the performance of three low‐Δ and three high‐Δ clones under well‐watered and draughted conditions. Plants were grown in pots imbedded in soil. Soil water content in the pots was maintained at either 0.16 or 0.06 kg H 2 O kg −1 soil. Within each water level, values for Δ and leaf intercellular CO 2 concentration ( c i ) were less for low‐Δ than high‐Δ clones and were negatively associated with both WUE i and WUE s . Even though shoot dry weight and Δ decreased with drought, the two traits were not correlated for either well‐watered or droughted clones. Across water levels, Δ was negatively correlated with WUE i ( r = −0.93**, df = 10) and with WUE s ( r = −0.98**, df = 10). Results show Δ in field‐grown crested wheatgrass was consistent across sites and was consistently related to c i , WUE i , and WUE s .