Dynamics of Root Development of Spring Wheat Genotypes Varying in Nitrogen Use Efficiency

Abstract

Three spring wheat genotypes (cv. Albis and Toronit and the experimental line L94491) identified to vary in nitrogen use efficiency characteristics, were studied in lysimeters under two levels of N supply (0 and 250 Kg N ha^-1) in 1999 and 2000. No. of roots cm^-2 were obtained from regular minirhizotron observations at soil depths of 0.10, 0.25, 0.45, 0.80 and 1.00 m and fitted to a logistic equation. The parameters of the logistic model were influenced by all study factors, indicating a high plasticity of the root system of spring wheat to respond to different soil conditions. A single main genotype effect was observed among all tested factors: the asymptotic no. of roots cm^-2 was significantly higher for Toronit than Albis and especially L94491 in the topsoil (0.10 and 0.30 m). Contrastingly, the N supply modified the asymptotic growth in 1999 at 0.10 m and in both years at 0.25 m as well as the root growth pattern at 0.80 in 1999 and at 0.10 m and 0.25 m soil depth in both years