Brazilian maize landraces variability under high and low phosphorus inputs

Landraces are considered important sources of abiotic stress tolerance. Among the different abiotic stresses, phosphorous (P) deficiency is considered one of the limiting factors in tropical and subtropical soils. Thus, the aim of the present work is to evaluate and compare P acquisition and use efficiency in landraces and improved varieties of maize in Brazil and classify varieties based on their performance (yield) under low (efficient versus inefficient)and high (responsive versus non-responsive) P supplementation. It also investigates the relationship among variables in regards to P use efficiency(PUE) and agronomic traits and evaluates genetic diversity among varieties. Thirteen landraces varieties and five improved varieties were evaluated in two P-contrasting experiments (with and without P application during sowing) in two counties (Londrina and Maringá), Paraná, Brazil. There was a wide genetic variability among the varieties for the agronomic and P efficiency traits. P acquisition efficiency(PAE) showed high correlation with PUE and grain yield (GY). On the other hand, no correlation was detected between PUE and GY for P use internal efficiency(PUTE). In the experiment without P at sowing, the improved variety ST0509 showed high values for PUE and GY, whereas, among the landraces, the varieties Amarelão, Caiano and Caiano 2 stood out, being considered promising varieties for future PUE breeding programs