Department of Food Science and Nutrition, College of Food and Agricultural Sciences, King Saud University, P. O. Box 2460, Riyadh 11451, Kingdom of Saudi Arabia
The grains of four sorghum cultivars (Tabat, Tetrom, WadAhmed and Gadambellia) were grown in a sandy clay soil with a pH 7.2 for two consecutive seasons under different levels (0, 2, 4, and 8 gm/5kg soil) of micronutrients fertilizer and a constant level of macronutrients (6 gm/5kg soil). After addition of the fertilizers and water to the soil, the pH dropped to 5.7. Macroelements (Ca, P, Mg, K and Na) content and extractability (bioavailability) of the harvested grains were investigated. The content of macro-elements of the grains harvested during both growing seasons was significantly (p ? 0.05) increased with increase in micronutrients dose. However, the grains harvested during the second season for all cultivars had significantly (p ? 0.05) higher amount of macroelements than that harvested during the first season. Calcium content of the cultivar Tabat and sodium content of the cultivar Tetron were increased by more than 100% as a maximum values during the second season. Macroelements extractability (bioavailability) was increased with micronutrients fertilization with very few exceptions. The maximum value of extractability recorded was 92.88% for Mg extracted from the grains of Tabat cultivars grown under 8 gm/5kg soil micronutrients. The results revealed that micronutrients fertilization of sorghum cultivars is an ideal method in improving macroelements contents. Moreover, the pH (5.7) is the suitable value for the acquisition of micronutrients by the plant.