Response of wheat cultivars to different soil nitrogen and moisture regimes: II. Nitrogen up‐take, partitioning and influx¹

Published as Paper no. 10506 from the Nebraska Agricultural Experiment Station, Lincoln, NE.

Abstract

Nitrogen (N) is one of the major mineral nutrients required for growth and development of plants. Soil water availability, N concentration at the root surface and the ability of plants to absorb N are the most important factors that affect N uptake and partitioning. The objective of this study was to use greenhouse and growth chamber environments to investigate how two contrasting water regimes (stress and nonstress) and different soil N concentrations affect the uptake and distribution of N among different plant parts of three cultivars of wheat (Triticum aestivum L.) at different stages of development Results showed that at the beginning of stem elongation and under non N limiting conditions, there was a high and positive correlation between shoot dry matter production and shoot N content. Under N deficient soils that received different N rates, shoot N content was more related to shoot N concentration than to dry matter. Root growth and N content of the ‘Saada’ cultivar were negatively affected by high soil N concentration. Under mild water stress or nonstressed conditions, N uptake by the shoot increased with increased soil N in all cultivars. Overall, severe water stress masked the effect of N supply, and decreased N uptake in the case of ‘Merchouch 8’ and ‘Saada’. Root N content was not affected by water stress but increased when N was supplied. At anthesis and after rewatering plants from boot stage to anthesis, the plants fully recovered, and those that were water stressed, increased their N absorption to a rate much higher than those that were stressed. Nitrogen influx (NI) decreased with water stress, but increased more with increased soil N under well watered conditions than under stress. “Merchouch 8’ had higher NI than ‘Saada’. From this study we can conclude that the effect of N supply on N content was masked by severe water stress, and ‘Nesma’ was less sensitive to this stress. At anthesis, plants that were previously water stressed increased their rate of N uptake during the recovery. Root N was not affected by water stress but increased when soil N was increased.

Notes

Published as Paper no. 10506 from the Nebraska Agricultural Experiment Station, Lincoln, NE.

Present address: Aridoculture Center, INRA, Settat, BP 290, Settat, Morocco.