INTERACTIONS BETWEEN ALUMINUM, MAGNESIUM AND CALCIUM WITH DIFFERENT MONOCOTYLEDONOUS AND DICOTYLEDONOUS PLANT-SPECIES

Growth inhibition of plants suffering from Al toxicity is generally ac companied by impaired root development which can be quantitatively des cribed by reduced specific root length (m g(-1) dry root). In addition , the uptake of nutrients such as Mg and Ca is inhibited. Increased su pply of either Mg or Ca can significantly diminish the negative effect of Al on root development and improve the Mg or Ca nutrition of the p lants. The positive effect of Ca is well established but the effect of Mg has been observed in only a few plant species. Therefore, the effe cts of increasing Mg and Ca supply on Al toxicity in plants of seven m onocots and eight dicots have been now examined in nutrient solution e xperiments. In general, Mg appears to be more effective than Ca in all eviating Al toxicity with the monocots, whereas the reverse is true fo r the dicots. Increased concentrations of Mg and Ca in solution seem t o protect the plants against Al toxicity by improving the Mg or Ca nut rition and by alleviating the toxic effect of Al on root development.