Response of plants to calcium concentration in flowing solution culture with chloride or sulphate as the counter-ion |
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Authors: | A K M S Islam C J Asher D G Edwards |
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Institution: | (1) Department of Agriculture, University of Queensland, 4067 St. Lucia, Queensland, Australia |
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Abstract: | Summary Solution calcium concentrations required for the growth of a range of plant species, including both monocotyledons and dicotyledons,
were determined in two experiments in which plants were grown in flowing solution culture at constantly maintained calcium
concentrations ranging from 0.5 to 3000 μM. Calcium chloride was used as the calcium source in the first experiment, calcium sulphate was used in the second.
At calcium concentrations of 10 μM and below, all species developed calcium deficiency symptoms. The severity of the deficiency was more pronounced in the dicotyledons
than in the monocotyledons. However, cassava was much more tolerant than all other dicotyledons and equally as tolerant as
rice, the most tolerant monocotyledon.
Solution calcium concentrations required for 90% of maximum yield were generally lower for monocotyledons (3 to 20 μM) than for dicotyledons (7 to 720μM) when calcium chloride was used as the calcium source. When calcium sulphate was used, 7 out of 11 species, including 3 monocotyledons,
required external calcium concentrations of 1200 μM and above. The results are discussed in relation to effects of solution composition and the choice of counter-ions on plant
response to calcium and other macronutrient cations. It is concluded that yield depressions due to toxicity of excesses of
chloride, and possibly other counter-ions, can lead to serious underestimation of limiting external cation concentrations
for plant growth. |
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Keywords: | Calcium deficiency symptoms Calcium concentration in tops Chloride toxicity Flowing solution culture Sulphate |
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