Electrophysiological factors in the influence of nitrate and ammonium ions on calcium uptake and translocation in tomato plants [nitrogen nutrition, trans-root electrical potential, Lycopersicum esculentum]
1980
Macklon, A.E.S. | Sim, A. (Macaulay Inst. for Soil Research, Aberdeen (UK). Dept. of Plant Physiology)
Tomato plants (Lycopersicon esculentum Mill. cv. San Marzano), grown in dilute nutrient solutions containing (in meq.1('-1)) 0.5 NaNO(,3), 0.5 NH(,4)NO(,3) or 0.25 (NH(,4))(,2) SO(,4) as the nitrogen source, were detopped for collection of xylem sap and measurement of trans-root electrical potentials. The plant parts and the xylem exudate were subsequently analysed for mineral content. The commonly observed effects of NH('+)(,4) were noted, including reduction of calcium concentration in the xylem sap, and of calcium content in stems and leaves, compared with NO('-)(,3)-fed plants. This effect was attributed principally to the less negative trans-root electrical potential measured in NH('+)(,4)-fed plants, and the resultant reduction of inward driving force on passively moving divalent cations.
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