The influence of CO2 and O3, singly and in combination, on gas exchange, growth and nutrient status of radish (Raphanus sativus L.)

摘要: SUMMARY Five days after emergence radish (Raphanus sativus L. ev. Cherry Belle) plants were transferred to a phytotron at the GSF Munchen, where they exposed in four large controlled climate chambers two atmospheric concentrations of CO2, (‘ambient’, daily means ∼ 385 μmol−1; elevated, 765 μmol mol−1) and O3 regimes (‘non-polluted’ air, 24 h mean 20 nmol mol−1; polluted 73 mol−1). Leaf gas-exchange measurements made intervals, visible damage, effects on growth, dry matter partitioning mineral composition assessed final whole-plant harvest 27 d. In ‘non-polluted air’ CO2 enrichment resulted progressive stimulation Asat, whilst there was decline g which decreased E (i.e. improved WUEi). The extra carbon fixed elevated stimulated growth root (+ hypocotyl) by 43 %, but no significant effect shoot or leaf area. Moreover, SLA LAR CO2-enriched suggested that less invested area expansion. Tissue N, S, P, Mg Ca lower (particularly + indicating total uptake these nutrients not affected an increase C:N ratio tissue. contrast, depressed (∼ 26%) induced slight stomatal closure, with result WUE, declined. All ‘polluted’ air developed typical symptoms injury, assimilation reflected reduced maintained expense root. addition, increased P K concentration tissue, enhanced from medium. However, affect tissue Ca. Interactions between gases complex, often subtle. general, counteracted (at least part) detrimental phytotoxic O3, conversely, O3reduced impact CO2. indications cumulative changes source: sink relations O3-exposed may limit plant response CO2-enrichment even greater extent long-term. future ecological significance interactions are discussed.