CATION NUTRITION OF BARLEY AS INFLUENCED BY SOIL SOLUTION COMPOSITION IN A SALINE SOIL

Abstract

Identification of nutritional disorders in crops growing on saline soils may facilitate the development of breeding or agronomic practices that improve yields in saline areas. An investigation was conducted under controlled environment conditions to identify possible cation deficiencies in barley (Hordeum vulgare 'Gait') grown under sulfate-dominated salinity stress. Soil was artificially salinized to produce a factorial of five salinity levels (ranging from approximately 6.5 to 17.5 dS m−1) and five salt types containing various ratios of Na:Mg:Ca. A control treatment (3.1 dS m−1) was also included. Barley was grown for 75 d and harvested for analysis of dry matter yield and tissue composition. Yield response of barley to salinity stress was not differentially affected by the type of salt used in salinization. Concentrations of sodium and magnesium in the plant tissue were generally increased by salinity stress, but these accumulations did not restrict yield since no consistent relationship was found between the concentrations of these cations and barley yield. Potassium concentration in the plants was inversely related to level of soil salinity, apparently because of an antagonistic effect of sodium, but was not consistently related to barley dry matter yield. Calcium uptake was also suppressed by soil salinity. In contrast to the results observed for other cations, a very strong relationship indicative of a yield response curve was observed between yield and calcium concentration in the plant tissue, particularly when the latter was expressed as a ratio of total cation concentration (R2 = 0.94). Furthermore, calcium concentration in the plant tissue and estimated calcium activity in the soil solution in highly salinized treatments were well below those considered adequate. These results suggest that calcium deficiency may have played an important role in restricting yield under salinity stress. The apparent calcium deficiency induced by salinity stress was attributed to reduced activity of calcium in the soil solution because of precipitation with sulfate and high ionic strength. Key words: Calcium, magnesium, potassium, sodium, salinity