Journal Article

Diel changes in nitrogen and carbon resource status and use for growth in young plants of tomato (<i>Solanum lycopersicum</i>)

Ruth Huanosto Magaña, Stéphane Adamowicz and Loïc Pagès

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 103, issue 7, pages 1025-1037
Published in print May 2009 | ISSN: 0305-7364
Published online March 2009 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcp043
Diel changes in nitrogen and carbon resource status and use for growth in young plants of tomato (Solanum lycopersicum)

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  • Ecology and Conservation
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Background and Aims

Modellers often define growth as the development of plant structures from endogenous resources, thus making a distinction between structural (WS) and total (W) dry biomass, the latter being the sum of WS and the weight of storage compounds. In this study, short-term C and N reserves were characterized experimentally (forms, organ distribution, time changes) in relation to light and nutrition signals, and organ structural growth in response to reserve levels was evaluated.

Methods

Tomato plants (Solanum lycopersicum) were grown hydroponically in a growth room with a 12-h photoperiod and an adequate supply of NO3 (3 mol m−3). Three experiments were carried out 18 d after sowing: [NO3] was either maintained at 3 mol m−3, changed to 0·02 mol m−3 or to 0 mol m−3. Plants were sampled periodically throughout the light/dark cycles over 24–48 h. Organ WS was calculated from W together with the amount of different compounds that act as C and N resources, i.e. non-structural carbohydrates and carboxylates, nitrate and free amino acids.

Key Results

With adequate nutrition, carbohydrates accumulated in leaves during light periods, when photosynthesis exceeded growth needs, but decreased at night when these sugars are the main source of C for growth. At the end of the night, carbohydrates were still high enough to fuel full-rate growth, as WS increased at a near constant rate throughout the light/dark cycle. When nitrate levels were restricted, C reserves increased, but [NO3] decreased progressively in stems, which contain most of the plant N reserves, and rapidly in leaves and roots. This resulted in a rapid restriction of structural growth.

Conclusions

Periodic darkness did not restrict growth because sufficient carbohydrate reserves accumulated during the light period. Structural growth, however, was very responsive to NO3 nutrition, because N reserves were mostly located in stems, which have limited nitrate reduction capacity.

Keywords: Solanum lycopersicum; tomato; nitrogen; carbon; structural growth; reserves; nitrate; amino acids; carbohydrate; carboxylate

Journal Article.  8256 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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