Influence of nitrogen deficiency or excess on a root system structure of maize and triticale seedlings grown under low and high soil density

Responses of maize and triticale seedlings, differing in the susceptibility to soil density stress, and grown under low (L-D) or high (H-D) soil density and poor (P-N), high (H-N) or control (C-N) nitrogen content in soil were investigated in relation to changes in physiological parametersdry matter of shoot (S), root (R), shoot to root ratio (S/R), relative growth ratio of shoot and root (RGR), chlorophyll content (SPAD), total roots number and length (TRN, TRL), root penetration ability (RPA) and ratio of deep rooting (RDR). The seedlings grown under high soil density (H-D) and control N-soil content (C-N) in comparison with L-D and C-N treatments showed a decrease in all measured parameters. Under poor and high nitrogen content, changes in the traits were higher for triticale than for maize. Higher differences between resistant and sensitive genotypes in TRN, TRL, RPA and RDR were observed particularly in the seedlings grown under H-D treatment. Differences in parameters values between seedlings grown under control and nitrogen-rich soil may be considered as a positive interaction between stresses. Our results suggest that the type of root structure (scattered, dimorphic) would be helpful in enhancing modelling and agronomic management for improved of plant stress tolerance.