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This thesis investigated the performance of sugarbeet genotypes in Germany under a range of environmental conditions in the field, partly in dry areas with and without irrigation, as well as under controlled water supply in the greenhouse. The genotypes exhibited significant variability for taproot and leaf yields, taproot to leaf ratio, and concentrations of sucrose, potassium, sodium, and α-amino nitrogen in the taproot. Under drought conditions, withholding irrigation reduced leaf and taproot growth, taproot to leaf ratio, and percentage of sucrose in dry matter, and resulted in the accumulation of α-amino nitrogen. Gas exchange was markedly affected by moderate drought, whereas effective quantum yield of photochemical energy conservation was impaired only under severe drought. 13C discrimination (CD) was greater in leaf than in taproot, and up to 2.4 parts per thousand lower in drought-stressed plants than in plants sufficiently supplied with water. This reduction in CD corresponded to approximately 24% higher water use efficiency (WUE) in drought-stressed plants. Only the leaf CD was correlated with WUE. Under all water regimes, genotypic differences were marginal for both dry matter and physiological parameters. Three previously published or submitted papers, on which this thesis is based, are included as reprints.
amino nitrogen, chemical composition, crop yield, drought,drought resistance, dry matter, gas exchange, genotypes, growth, leaves,plant composition, plant water relations, roots, sodium, stress, stressresponse, sucrose, sugarbeet, water stress, water use efficiency,Germany, Beta vulgaris var. saccharifera, Beta vulgaris, Beta,Chenopodiaceae, Caryophyllales, dicotyledons, angiosperms,Spermatophyta, plants, eukaryotes, Western Europe, Europe, DevelopedCountries, European Union Countries, OECD Countries, chemicalconstituents of plants, drought tolerance, saccharose, Field Crops(FF005) (New March 2000), Plant Breeding and Genetics (FF020), PlantComposition (FF040), Plant Water Relations (FF062), Plant Production(FF100), Environmental Tolerance of Plants (FF900)