Root morphology determines the nitrogen uptake of wheat species at maturity

Wheat production in the UK relies heavily on nitrogen (N) fertiliser for high yield and protein content. Application of N fertiliser may affect negatively farmers’ revenue and the environment since all amount of fertiliser applied to the field is not taken by the plant. Therefore, the development of wheat genotypes with efficient root systems to uptake more N fertiliser would be beneficial. A controlled environment experiment was conducted to study root morphological traits, plant growth yield and N uptake in different wheat species. Seven genotypes included cultivated emmer (Triticum dicoccum), spelt (T. spelta L.) and modern bread wheat (T. aestivum) under three N levels were examined. A split-plot design was used in the experiment where the main plot factor was N levels and sub-plot factor was genotypes replicated three times. Root samples at five depth layers were scanned and analysed using WinRHIZO software at anthesis and maturity. Total root length, root volume, root biomass, root diameter, root length density, rooting depth and root N uptake efficiency were recorded. Plant N uptake, N uptake efficiency, N utilisation efficiency and N use efficiency were calculated at maturity (excluding N in roots). The interaction effect between main factors and N level was not significantly different for all measured root traits except N uptake efficiency of roots, growth and yield traits at anthesis and maturity while significantly different among genotypes. Spelt genotypes recorded the highest total root length, root volume, root biomass and root length density at all depth layers while emmer genotypes recorded the greatest root N uptake efficiency. Plant N uptake was significantly different between genotypes where all spelt genotypes had high plant N uptake followed by bread wheat and emmer. Plant N uptake of the genotypes had a very strong positive relationship with total root length, root volume, root biomass and rooting depth of the genotypes. Therefore, it could be concluded that the high plant N uptake of spelt may be due to the robust and vigorous growth of root systems.