Nitrate uptake and N allocation in Triticum aestivum L. and Triticum durum Desf. seedlings

Abstract

Inter- and intra-species differences in nitrate uptake and N allocation were studied in wheat seedlings. Two collections of wheat cultivars Triticum aestivum and Triticum durum were grown at controlled conditions in hydroponics (773µM NO<sub>3</sub><sup>–</sup>, i.e. 10.8 ppm N-NO<sub>3</sub><sup>–</sup>). At the age of 3 weeks the net rate of nitrate uptake was measured in depletion experiments and it was expressed as µmol NO<sub>3</sub><sup>– </sup>per g of root fresh weight per hour (µmol/g FW/h). Nitrate uptake capacity of the whole root system was expressed as µmol NO<sub>3</sub><sup>– </sup>per plantper hour (µmol/plant/h). At the same time wheat plants were harvested and analyzed for nitrogen content. In contrast to the net rate of NO<sub>3</sub><sup>– </sup>uptake (3.98–8.57 µmol/g FW/h) the net NO<sub>3</sub><sup>– </sup>uptake capacity of T. aestivum roots (6.37–11.66 µmol/plant/h) significantly differed from T. durum roots (15.26–22.69 µmol/plant/h). Within T. aestivum collection cultivar Roxo exhibits the lowest value in both traits (3.98 µmol NO<sub>3</sub><sup>–</sup>/g FW/h and 6.67 µmol NO<sub>3</sub><sup>–</sup>/plant/h). By contrast Strela was characterized by relatively low NO<sub>3</sub><sup>– </sup>uptake rate (5.47 µmol/g FW/h) and the highest NO<sub>3</sub><sup>– </sup>uptake capacity (11.66 µmol/plant/h). Intra-species differences in T. durum group were not significant. In both species about 70% total nitrogen was found in shoot. Statistically significant differences in nitrogen content and its allocation were affected by growth rate in early stages of development.