Influence of root NH4(+) and NO3(-) content on the temperature response of net NH4(+) and NO3(-) uptake in chilling sensitive and chilling resistant Lycopersicon taxa
1991
Smart, D.R. | Bloom, A.J.
We studied the influence of internal ammonium and nitrate content on the temperature response of ammonium and nitrate uptake in both chilling sensitive and chilling resistant tomatoes. Three taxa were examined: Lycopersicon esculentum Mill. cv. T-5, a chilling sensitive cultivar, Lycopersicon hirsutum Humb. and Bompl. LA1264, a wild, chilling sensitive accession from the lowlands of Ecuador, and Lycopersicon hirsutum LA1778, a chilling resistant accession from the highlands of Peru. Short exposures (4 h) of L. esculentum cv. T-5 to chilling temperatures irreversibly inhibited ammonium absorption for at least 6 h. Nitrate absorption in this taxon and ammonium and nitrate absorption in the L. hirsutum accessions recovered fully and immediately from such exposures. The chilling resistant accession, L. hirsutum LA1778, showed a lower Q10 for ammonium absorption (1.54 +/- 0.10. mean +/- s.e.) than its chilling sensitive relatives, L. hirsutum LA1264 (2.37 +/- 0.35) and L. esculentum cv. T-5 (1.92 +/- 0.11). The temperature response of nitrate absorption depended on internal nitrate status; plants grown at high levels of ammonium and nitrate (200 mmol m-3) showed higher Q10's for nitrate uptake (2.29 +/- 0.10) than those depleted of internal NO3(-) (1.86 +/- 0.12).
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