The effect of rhizosphere dissolved inorganic carbon on gas exchange characteristics and growth rates of tomato seedlings
| Autor: | M.B. Richards, Michael D. Cramer |
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| Rok vydání: | 1999 |
| Předmět: | |
| Zdroj: | Journal of Experimental Botany. 50:79-87 |
| ISSN: | 1460-2431 0022-0957 |
| DOI: | 10.1093/jxb/50.330.79 |
| Popis: | The possibility that an enhanced supply of dissolved inorganic carbon (DIC = CO 2 + HCO 3 - ) to the root solution could increase the growth of Lycopersicon esculentum (L.) Mill, cv. F144 was investigated under both saline and non-saline root medium conditions. Tomato seedlings were grown in hydroponic culture with and without NaCl and the root solution was aerated with CO 2 concentrations in the range between 0 and 5000 μmol mol -1 . The biomass of both control and salinity-stressed plants grown at high temperatures (daily maximum of 37°C) and an irradiance of 1500 μmol m -2 s -1 was increased by up to 200% by enriched rhizosphere DIC. The growth rates of plants grown with irradiances of less than 1000 μmol m -2 s -1 were increased by elevated rhizosphere DIC concentrations only when grown at high shoot temperatures (35 C) or with salinity (28°C). At high light intensities, the photosynthetic rate, the CO 2 and light-saturated photosynthetic rate (J max ) and the stomatal conductance of plants grown at high light intensity were lower in plants supplied with enriched compared to ambient DIC. This was interpreted as 'down-regulation' of the photosynthetic system in plants supplied with elevated DIC. Labelled organic carbon in the xylem sap derived from root DI 14 C incorporation was found to be sufficient to deliver carbon to the shoot at rates equivalent to 1% and 10% of the photosynthetic rate of the plants supplied with ambient- and enriched-DIC, respectively. It was concluded that organic carbon derived from DIC incorporation and translocated in the xylem from the root to the shoot may provide a source of carbon for the shoots, especially under conditions where low stomatal conductance may be advantageous, such as salinity stress, high shoot temperatures and high light intensities. |
| Databáze: | OpenAIRE |
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