Induced toxicities of aluminum and manganese in sweet sorghum: IV. Relations between P, K and Al

Abstract

Four sweet sorghum varieties (CMS x S 603,Br 500, Sart and Br 602) were grown in a modified Hoagland's solution in order to supply varying levels of Al, P and K. Dry matter production was measured. The material was analysed for P, K, Ca, Mg and Al. The following conclusions could be drawn: a) a stimulation on growth of some varieties was observed when a given combination among Al and other nutrient levels was provided; b) by increasing K level in the nutrient solution more tolerance to Al toxicity was observed, as long as P was present in high concentration in the substrate; c) a high level of K in the nutrient solution, such as thal given in Hoagland's solution, does not allow to differentiate cultivars with respect to tolerance to Al toxicity; d) there were differences among varieties with respect to tissue P,K, Ca, Mg and Al concentrations wich were associated with maximum and minimum growth.