Potential root depth development and nitrogen uptake by tetraploid bahiagrass hybrids

Abstract

The objectives were to develop a screening technique to evaluate the tetraploid germplasm of Paspalum notatum Flugge (bahiagrass) for potential rate of root depth development (RRDD), estimate the variability for RRDD among hybrids, and analyze the association between RRDD and nitrogen (N) uptake. First, a screening technique was developed based on the evaluation of two clones grown in clear acrylic columns of different sizes, filled with mineral or organic substrates. The RRDD response was determined to be constant across substrates, and tube sizes. Second, differences in RRDD among thirteen clones were compared by growing plants in acrylic columns filled with mineral substrate. Genetic variability was identified among the bahiagrass germplasm for RRDD. Greater RRDD values resulted in greater root and shoot mass, indicating that RRDD was related to early vigor. Finally, to evaluate the relation between RRDD and N uptake, labeled N (15N) was injected either at the depth of the deepest root of each clone or at the maximum depth of all clones. Rapid root depth development was a determining factor for rapid access and uptake of nitrogen present in deep soil layers. This relationship might explain why clones exhibiting rapid root penetration also showed greater early vigor.