PHYSIOLOGICAL AND NUTRIMENTAL RESPONSES OF RICE VARIETIES TO ALUMINIUM CONCENTRATION

Abstract

In acid soils (pH < 5), the high concentration of trivalent aluminum (Al³⁺) in solution reduces crop production and is toxic for most plant species, although different responses to Al are observed among genotypes. In this study we evaluated the effect of three Al concentrations (0, 200 y 400 μM) added to the Steiner´s nutrient solution at 20 % in three Mexican rice varieties (‘Temporalero’, ‘Huimanguillo’, ‘Tres Ríos’) and a japanese one (‘Koshihikari’); under greenhouse conditions, in a factorial 4 x 3 arrangement under a completely randomized experimental design. Both factors (variety and Al concentration) significatively (pH ≤ 5) affected plant height at the end of the experiment. The ‘Koshihikari’ plants treated with 400 μM Al showed the shortest (pH ≤ 5) plants, while ‘Temporalero’ plants were the less affected. With the exception of ‘Tres Ríos’, the other three varieties showed drastic damages on root cell structure. Both factors affected (P ≤ 0.05) the leaf concentrations of Al, Ca, K, Mg and P. The lowest levels of these nutrients were found in ‘Koshihikari’ plants. The Mexican variety ‘Tres Ríos’ concentrated lower amounts of Al in leaves compared to ‘Temporalero’ and ‘Huimanguillo’ (0.57 vs. 0.61 y 0.71 mg kg^-1, respectively), and its Mg concentration was unaffected by the Al treatments; furthermore, the levels of P in ‘Tres Rios’ were less affected by Al since they were diminished only by 5 % in plants treated with 400 μM Al, compared to the control plants (without Al in the solution), while the P levels decreased by 38 % in ‘Temporalero’, and by 55 % in ‘Huimanguillo’. We conclude that the Mexican rice variety ‘Tres Ríos’ is tolerant to Al because it did not show root damages and accumulated less Al and more Mg y P in leaves.