CLASSIFICATION OF SOYBEAN GENOTYPES AS TO EFFICIENCY AND RESPONSE TO PHOSPHORUS USE IN A SANDY CLAY OF BRAZILIAN CERRADO.

Abstract

Phosphorus (P) deficiency has been identified as one of the main abiotic stresses that limits soybean productivity under tropical conditions - the objective of the research was to evaluate the efficiency of P utilization of 25 soybean cultivars [Glycine max (L. ) Merrill.] Cultivated in a sandy soil of the Brazilian Cerrado. Responsive and efficient soybean genotypes in terms of P utilization were classified by the method of Fageria and Kluthcouski (1980) and the hierarchical method of clustering of minimum variance of Ward to discriminate similar groups. The experiment was carried out in a randomized block design in a 2 × 25 factorial design with four replications. The treatments consisted of two levels of P availability in the soil [low availability (20 mg kg–1) and high availability (200 mg kg–1)] and 25 soybean cultivars where the height of insertion of the first pod was evaluated. , number of pods per plant, number of grains per pod, mass of 1000 grains and grain yield. With the results of grain production, the efficiency of response to phosphate fertilization was calculated for the determination of a new grouping technique according to the similarity between genotypes.