Nitrogen incorporation and remobilization in different shoot components of field-grown winter oilseed rape (Brassica napus L.) as affected by rate of nitrogen application and irrigation

Abstract

The seasonal course of nitrogen uptake, incorporation and remobilization in different shoot components of winter oilseed rape (Brassica napus L.) was studied under field conditions including three rates of 15N labelled nitrogen application (0, 100 or 200 kg N ha 1 ) and two irrigation treatments (rainfed or watered at a deficit of 20 mm) . The total amount of irrigation water applied was 260 mm, split over 13 occasions in a 7-week-period ranging from 1 week before onset of flowering until 4 weeks after flowering .Nitrogen application and irrigation increased plant growth and nitrogen accumulation . Irrespective of N and irrigation treatment more than 50% of total shoot N was present in the stem when flowering started . At the end of flowering, pod walls were the main N store containing about 30-40% of shoot N . The quantities of N remobilized from stems and pod walls amounted in all treatments to about 70% of the N present in these organs at mid-flowering . At harvest, stem and pod walls each contained about 10% of total shoot N, the remaining 80% being incorporated into seeds. The main component contributing to the response of seed N accumulation to nitrogen application and irrigation was pods in axillary racemes . Up to 20 kg N ha 1 , corresponding to about 10% of final shoot N content, was lost from the plants by leaf drop .Irrigation increased the recovery at harvest of applied N from 30% to about 50%, while the level of N application did not affect the N recovery . 15 N labelled (fertilizer derived) nitrogen constituted a greater proportion of the N content in old leaves than in young leaves and increased with age in the former, but not in the latter . Relative to soil N, fertilizer derived N also contributed more to the N content of vegetative than to that of reproductive shoot components . Small net changes in shoot N content after flowering reflected a balance between N import and export, leading to continuous dilution of 15 N labelled N with unlabelled N.

Diverse concepts of breeding for nitrogen use efficiency. A review

“…Not only photosynthesis of siliques but also that of stems plays an important role in providing the assimilates necessary for seed filling (Diepenbrock 2000;Labra et al 2017). However, this cannot last long as the organic nitrogen necessary for seed formation also must come from translocation from these organs (Schjoerring et al 1995).…”

Response of seed tocopherols in oilseed rape to nitrogen fertilizer sources and application rates

“…Rapeseed, in particular the canola type, has a high N demand. Efficient supply of N fertilizer is an important factor affecting its yield and seed quality (Grant and Bailey, 1993;Schjoerring et al, 1995;Weisler et al, 2001). Three main variables, including application rate, timing, and chemical form, are considered important in implementing an efficient N fertilizer management program.…”

Modeling Nitrogen Uptake in Oilseed Rape cv Capitol during a Growth Cycle Using Influx Kinetics of Root Nitrate Transport Systems and Field Experimental Data

“…However, yields remain highly variable. As a consequence, oilseed rape has been extensively studied to identify key components of yield and to improve them by more effective nitrogen (N) application with the target of reducing environmental impacts such as N leaching and improving N use efficiency for seed filling (Boelcke et al, 1991;Habekotté, 1993;Schjoerring et al, 1995;Sieling and Christen, 1997;Vos and van der Putten, 1997). Many mathematical models have been built to simulate crop growth, development, and yield (BRASNAP-PH, Habekotté, 1997a; and LINTUL BRASNAP, Habekotté, 1997b).…”