MICRONUTRIENT CONCENTRATION AND ROOT GROWTH IN RICE VARIETIES EXPOSED TO ALUMINUM

Abstract

Aluminum (Al³⁺) is one of the most limiting factors of agricultural production in acid soils with pH lower than 5 in tropical regions worldwide. Rice (Oryza sativa L.) has showed to be tolerant to this stress factor, and differences in tolerance responses to Al have been observed among genotypes. We evaluated the effect of three Al concentrations (0, 200 and 400 μM AlCl₃ 6H₂O) in the nutrient solution on the foliar concentration of micronutrients (Cu, Fe, Mn y Zn) and root length in four rice genotypes (‘Huimanguillo’, ‘Koshihikari’, ‘Temporalero’ and ‘Tres Ríos’) grown under greenhouse conditions, in a factorial experiment. Interaction between factors evaluated (variety x Al concentration) showed significant effects on the concentrations of the four micronutrients evaluated and on root length as well. In general, as Al concentration was raised in the nutrient solution, an increase of the Cu and Fe concentrations was evident in the four varieties, while Mn and Zn concentrations diminished. The highest reduction on micronutrient concentration was observed in the varieties ‘Huimanguillo’, ‘Koshihikari’ and ‘Tres Ríos’, whereas the variety ‘Temporalero’ was less affected. Concerning root length, the highest levels of Al in the nutrient solution significantly caused a reduction in this variable, and the varieties most affected were ‘Temporalero’ and ‘Tres Ríos’. We conclude that Al differentially affects the rice genotypes evaluated, and that this metal shows diminished to Cu and Fe, and antagonism to Mn and Zn.