Light regulation of root and leaf NO3− uptake and reduction in the floating macrophyte Lemna minor

作者：Nina Cedergreen, Tom Vindbæk Madsen · 发表于：New Phytologist · 年份：2003 · DOI：10.1046/j.1469-8137.2003.00936.x · 被引用次数：60 · 研究领域：Plant Stress Responses and Tolerance、Marine and coastal ecosystems、Plant responses to elevated CO2

• The regulation of NO3− uptake kinetics and reduction in relation to long- and short-term changes in irradiance was explored in roots and photosynthetic tissues of Lemna minor. • The NO3− uptake kinetics, nitrate reductase activity, plant morphology, chlorophyll and tissue NO3−, organic-N, starch and sugars were measured on roots and fronds of L. minor grown at four combinations of irradiance- and NO3− availability. • Long-term acclimatizations paralleled those of terrestrial plants. Short-term changes in irradiance, however, changed frond NO3− uptake proportionally with frond chlorophyll and N content, indicating a relationship between responsiveness and the metabolic potential of the plants. Root uptake changed to balance the change in frond uptake keeping whole plant uptake varying by < 40%. Nitrate reductase activity was primarily located in the roots and was correlated with frond uptake, indicating a transport of NO3− from shoot to root before reduction. • This study shows that irradiance can affect the contribution of root and leaf uptake by aquatic plants and that roots play a major role in NO3− reduction despite large foliar uptake.