Effect of sulphate on photosynthesis in greenhouse–grown tomato plants

Abstract

Sulphate accumulates in the rhizosphere of plants grown in hydroponic systems. To avoid such sulphate accumulation and promote the use of environmentally sound hydroponic systems, we examined the effects of four sulphate concentrations (0.1, 5,2, 10.4 and 20.8 mM) on photosynthesis, ribulose‐l,5‐bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) activities and related physiological processes in greenhouse–grown tomato plants (Lycopersicon esculentum Mill. cv. Trust). The lowest sulphate concentration (0.1 mM) significantly decreased photosynthetic capacity (Pc) and Rubisco activities on a leaf area basis. This result was supported by our data for dry matter per plant, which was low for plants in the 0.1 mM treatment. The photosynthesis‐related variables such as leaf conductance, chlorophyll and soluble protein were lowest for the 0.1 mM treatment. Both total Rubisco activity and the activated ratio were reduced with this treatment. However, Rubisco activities expressed per g of protein or per g of chlorophyll were not significantly affected. These results suggest that sulphur deficiency depressed Pc– by reducing the amount of both Rubisco and chlorophyll and by causing an inactivation of Rubisco. The ratio of organic sulphur vs organic nitrogen (S/N) in plants of the 0.1 mM treatment was far below the normal values. This low S/N ratio might be accountable for the negative effect of low sulphate on Pc and plant growth. Pc and dry matter were not affected until sulphate concentration in the nutrient solution reached a high level of 20.8 mM.

Effects of sulfur nutrition on the growth and photosynthesis of rice

“…In young leaves of wheat, the effects of S deprivation on the CO 2 assimilation rates were detected before any decrease in the dry weight was observed (Gilbert et al 1997). Reduced photosynthesis with lower leaf S content has also been observed in other crops (Terry 1976;Xu et al 1996;Leoncini et al 1997;Sexton et al 1997). Although the total leaf N content decreased slightly with the decrease in the sulfate concentration in the medium, the Rubisco and chlorophyll contents of the second fully expanded leaf decreased largely below the 0.1 mM SO/-treatment (Fig.…”

“…Reduced photosynthesis under sulfur-deficient conditions was observed in barley (Karmaker et al 1991;Chen and Huerta 1997), rapeseed (Leoncini et al 1997), spinach (Dietz and Heilos 1990), soybean (Sexton et al 1997), and tomato (Xu et al 1996). S deprivation decreased the CO 2 assimilation rates in all the leaves of young wheat seedlings (Gilbert et al 1997).…”

“…Leaves of S-deficient plants have low chlorophyll contents (Dietz and Heilos 1990;Xu et al 1996;Gilbert et al 1997;Leoncini et al 1997;Blake-Kalff et al 1998). The decrease in the chlorophyll content caused by S deficiency is more evident in expanding young leaves than in old leaves (Dietz and Heilos 1990;Gilbert et aI.…”

Effect of light intensity on the growth and photosynthesis of rice under different sulfur concentrations

“…Leaves of sulfur-deficient plants exhibit low contents of chlorophyll and Rubisco (Dietz and Heilos 1990;Xu et al 1996;Gilbert et al 1997;Leoncini et al 1997;Sexton et al 1997;Blake-Kalff et al 1998). The reduced photosynthesis associated with S deprivation has been attributed to the decline of the amounts of the components of the photosynthetic apparatus.…”

Sulfate Fertilization Preserves Tomato Fruit Nutritional Quality

“…Tomato S deficiencies develop rapidly [19], appearing as purple dots on the leaf blade and necrosis at the margins of mature leaves [20]. The young leaves turn yellow and shrink upwards and later develop necrosis in all leaf parts [21], and photosynthesis is impaired [22].…”