Potassium uptake kinetics in native forage grass species from Pampa Biome

Cinética de absorção de potássio em espécies de gramíneas forrageiras nativas do bioma Pampa

ABSTRACT:

This study quantified K uptake kinetic parameters in grass species Paspalum notatum, Paspalum urvillei and Axonopus affinis to associate them with growth. Ten milliliters (10 ml) of nutrient solution were collected in two-liter pots - with five repetitions in 24 hours - in order to determine K concentrations in the samples. Shoot and root dry matter, root length, volume, diameter and surface area, as well as kinetic parameters associated with nutrient uptake (V_max, K_m, C_min and I) were determined. Species P. notatum was the one presenting the highest root, shoot and total dry matter production, as well as the highest root volume. P. urvillei recorded the highest K content, which may be associated with thinner roots and greater root surface area. A. affinis recorded the highest V_max value, which led to greater K uptake efficiency.

Key words:
Paspalum; Axonopus; kinetic parameters; nutrient uptake; maximum inflow