Calcium requirement of wheat in saline and non-saline conditions

• Published in: Plant and soil 2010-02, Vol.327 (1-2), p.331-345
• Main Authors: Genc, Y, Tester, M, McDonald, G. K
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Biological and medical sciences; Biomedical and Life Sciences; Calcium; Durum wheat; Ecology; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Genotype & phenotype; Genotypes; Hydroponics; Leaves; Life Sciences; Nutrient solutions; Plant biology; Plant growth; Plant Physiology; Plant Sciences; Plants; Regular Article; Salinity; Salinity tolerance; Salt tolerance; Sodium; Sodium chloride; Soil salinity; Soil Science & Conservation; Soil sciences; Soil solution; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Toy industry; Wheat
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-009-0057-3

Supplemental calcium (Ca²⁺) is used in hydroponic studies on salinity to lessen the potential for Ca²⁺ deficiency. However, the Ca²⁺ concentration and the sodium (Na⁺): Ca²⁺ ratio used vary considerably. The implications of using a wide range of Na⁺: Ca²⁺ ratios for studies of salinity tolerance in wheat are not known. Also, despite the risk of development of Ca²⁺ deficiency under salinity stress, there are few reliable reports on the critical level of Ca²⁺ which can be used to diagnose Ca²⁺ deficiency in wheat. Two experiments were conducted to examine Ca²⁺ requirements of wheat under saline and non-saline conditions and to derive a critical level for Ca²⁺. Four bread wheat genotypes (Triticum aestivum L.) and a durum wheat genotype [Triticum turgidum subsp. durum) (Desf.) Husn.] with known differences in salinity tolerance were grown at 100 mM NaCl for four weeks with varying levels of external Ca²⁺ which resulted in Na⁺:Ca²⁺ ratios of 30, 20, 15, 5 and 2. The critical Ca²⁺ concentration was defined in a second experiment by growing the same wheat genotypes at seven levels of Ca²⁺ (0.05, 0.1, 0.2, 0.5, 1, 2 and 10 mM) under non-saline conditions. When grown at 100 mM NaCl salinity tolerance was greatest when the Na⁺:Ca²⁺ ratio ranged from 5 to 15. Growing plants at lower or higher Na⁺:Ca²⁺ ratios induced nutrient imbalances and additional osmotic stress which reduced the growth of plants. Transient Ca²⁺ deficiency occurred at high Na⁺:Ca²⁺ ratios and low Mg²⁺ occurred at the lowest Na⁺:Ca²⁺ ratio. Adding NaCl raised the tissue Na⁺ concentration and reduced the Ca²⁺ concentration and the most appropriate Na⁺:Ca²⁺ ratio in the solution was that which resulted in tissue Ca²⁺ concentrations similar to those of non-salinised plants. The critical level of Ca²⁺ in the youngest fully emerged leaf blades was 15-23 mmol kg⁻¹ DW (600-900 mg kg⁻¹ DW).