Growth response of coffee tree shoots and roots to subsurface liming

In the greenhouse growth of two coffee-tree varieties, Catuai (sensitive) a nd Icatu (tolerant) to aluminum, was evaluated in surface-fertilized and li med soil following subsurface treatment with seven lime levels (0.0; 0.49; 1.7; 2.9; 4.1; 6.6 and 9.3 t/ha). Plants were grown for 6.5 months in soils in PVC columns, subdivided into two horizons. In the lower 12 - 34 cm dept h horizon, soil Al saturation varied between 93 and 0%. For both varieties evaluated, shoot dry weight and leaf area remained unchanged following lime stone application. This fact shows that surface layer correction permitted normal shoot growth. High Al saturation resulted in decrease of root dry we ight percent, root length percent and root surface percent in the 12-34 cm horizon, which were compensated by higher percentages of these properties i n the upper 0-12 cm horizon. The ratio between root surface - root dry matt er (cm(2)/g) of Catuai variety was increased by limestone application to th e lower soil horizons, indicating that roots turn longer and thinner, when Al soil saturation decreased. This also shows a great sensitivity to Al of the Catuai variety. In contrast, in the Icatu variety, all root characteris tics remained stable at all levels of Al tested.