|Author:||Jensen, K. B. ; Asay, K. H. ; Johnson, D. A. ; Waldron,B. L.|
|Book Group Author:||NA|
Carbon isotope discrimination (Δ) has been proposed as an indirect criterion for evaluating water-use efficiency; however, limited information is available regarding the relationship between Δ and dry matter yield (DMY) at different levels of irrigation. Ten cultivars of tall fescue (Festuca arundinacea) were established in the field (Utah, USA) under a line-source irrigation system and defoliated five to six times per growing season. Objectives of our 2-year study were to evaluate: (i) trends in Δ across a gradient of four water levels (WL-2, wettest to WL-5, driest) at a mid-summer harvest, (ii) the consistency among grass cultivars at one WL across two harvest dates, and (iii) relationships between Δ and DMY within and across water levels. Consistent and significant differences (P<0.05) were found among cultivars for Δ when evaluated at WL-2 for Harvests 2 and 4 in successive years. Cultivars also differed significantly for Δ (P<0.01) across four water levels when evaluated at Harvest 4. Relative differences among cultivars were consistent across water levels and between harvest dates. Although a curvilinear trend was evident for some cultivars, mean Δ values decreased in a near linear manner from WL-2 to WL-5. Based on orthogonal polynomials, the mean trend across water levels was partitioned as 95% linear and 5% quadratic. Correlations between Δ and DMY were nonsignificant at the higher water levels (WL-2 and 3), but correlations were positive at the lower water levels (WL-4 and 5). We conclude that under lower water levels, selection for low Δ in tall fescue cultivars will likely lead to decreased forage yield.
|Pages:||157 - 162|
|Journal:||Canadian Journal of Plant Science|
carbon, crop yield, fodder crops, irrigation, irrigationsystems, isotopes, Mollisols, plant water relations, soil types, watercontent, water use efficiency, USA, Utah, Festuca arundinacea, Festuca,Poaceae, Cyperales, monocotyledons, angiosperms, Spermatophyta, plants,eukaryotes, North America, America, Developed Countries, OECD Countries,Mountain States of USA, Western States of USA, USA, Festuca elatior,United States of America, watering, Forage and Fodder Crops (FF007) (NewMarch 2000), Plant Physiology and Biochemistry (FF060), Plant WaterRelations (FF062), Plant Production (FF100), Soil Water Management(Irrigation and Drainage) (JJ800) (Revised June 2002) [formerly SoilWater Management]