Temperature Influence on Ammonium and Nitrate Absorption by Lettuce1
- J. N. E. Frota and
- T. C. Tucker2
The uptake patterns of NH4+ and NO3- in lettuce plants (Lactuca sativa L., cultivar ‘Climax’) were determined using inverse 15N isotope dilution techniques under air and root temperatures of 8, 13, 18, and 23C and the same air temperatures with an initial root environmental temperature of 2C. The absorption patterns for both NH4+ and NO3- at each nutrient solution and air temperature were linear functions of time. The absorption rates for NH4+ and NO3- were increased by increasing the air, root, or both air and root environmental temperatures. Nitrate uptake was influenced more by temperature than the absorption of NH4+. The NH4+ to NO3- absorption ratio increased when the temperature decreased. A higher temperature coefficient for NO3- was obtained. The translocation rates to tops for NH4+ increased as temperature increased from 8 to 23C, but reached a maximum at 18C for NO3-.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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