Genetic Divergence in Corn Genotypes for High and Low Phosphorus in Pará, Brazil

Aims: The objective of this study was to estimate the genetic divergence between ten corn genotypes in the 2017/18 crop, under high and low phosphorus. Study Design: The experimental design used in each test was randomized blocks, the treatments were: ten genotypes in two levels of phosphorus and three replications. Place and Duration of Study: Sítio Vitória, municipality of Santa Maria das Barreiras, state of Pará, Brazil, in the 2017/18 crop. Methodology: The experimental plot consisted of four lines five meters long, spaced with 0.90 m between the lines, with approximately 55,000 plants per hectare in the harvest. The genotypes used: 2B655, AG 1051, AG 8088, AL BANDEIRANTE, ANHEMBI, BR 206, BRS 3046, CATIVERDE, ORION e PR 27D28. The following agronomic characteristics were evaluated: plant height, ear height, ear diameter, ear length, number of grains per row, yield per plant and grain yield. Genetic divergence was estimated from Mahalanobis distances and genotypes were grouped by Tocher optimization methods. Results: Genetic dissimilarity measurements, at each dose of phosphorus, showed a high magnitude (D2= 9.72 to 1484.87). Cluster analysis separated the genotypes into four groups at low phosphorus and two groups at high phosphorus. The characteristics that most contributed to genetic divergence, in the two levels of phosphorus, were yield per plant and grain yield. Conclusion: There was a higher genetic divergence between genotypes AG 1051 and BANDEIRANTE in the low phosphorus assay and between the genotypes ANHEMBI and AL BANDEIRANTE in the high phosphorus assay. With this, these crosses are promising to obtain lineages in both tests.