Stickstoffaufnahme und Stickstoffrückstände von Hauptfrucht‐und Ausfallrapsbeständen

Abstract

Nitrogen Uptake and Nitrogen Residuals of Winter Oil‐Seed Rape and Fallout Rape The objective of the investigation was a study of the relationship between seed dry‐matter production and vegetative dry‐matter production in oil‐seed rape crops and their dependence on the production conditions. In addition to the relationship between the N‐uptake during the vegetation period and the N‐residue after harvest was of major interest. Furthermore the potential for N‐uptake in fallout rape was measured. Over two vegetation periods factorial field experiments with winter oil‐seed rape, cv. Lirabon, different drilling techniques and different nitrogen fertilization levels were tested. Measured traits were: the dry‐matter accumulation including root mass and fall‐off leaf‐material mass, the N‐uptake of both the oil‐seed crops and the fallout rape stands, and, simultaneously, the soil NO3‐N content. Finally the harvest indices and the N‐harvest indices were calculated. Combined with a N‐uptake of up to 330 kg N/ha, oil‐seed rape crops produced up to 200 dt dry matter/ ha. At seed yield levels of 33dt/ha (d.m.), harvest indices varied from 0.14—0.23 and N‐harvest indices varied from 0.30–0.50. As a result of the residue of vegetative plant material at harvest, leaf losses before harvest and the soil NO3‐N‐contents at harvest up to 275 kg N/ha remained in the field. After the harvest of oil‐seed rape, the soil NO3‐N‐contents were quickly reduced by emerging and growing fallout rape stands. However, following soil‐preparation measures in the autumn, a continuous rise in the soil NO3‐N‐content was observed.

Contribution of Nitrogen Uptake and Retranslocation during Reproductive Growth to the Nitrogen Efficiency of Winter Oilseed-Rape Cultivars (Brassica napus L.) Differing in Leaf Senescence

“…Therefore, a high N retranslocation for which the N harvest index (NHI) is an overall indicator, is of greater importance as component of NUE. The NHI was 0.41 and 0.55 for limited (N0) and sufficient N supply (N160), respectively ( Figure 8B) and thus in the range as reported by Aufhammer et al [3]. But depending on environment and agronomic practices the N allocation to the grains can be highly efficient and reach a NHI of up to 0.83 [23].…”

“…For optimum grain yield, winter oilseed-rape requires about 200 kg N¨ha´1 [2]. Under best agronomic practices, a grain yield of 4.5 t¨ha´1 causes an N budget surplus of around 60 kg N¨ha´1 for which an incomplete depletion of plant available soil-N by the crop and an incomplete retranslocation of N from vegetative plans parts into the grains are responsible [3,4]. Thus, a substantial part of the N required for optimal crop development is Remaining green leaves on the main stem of the winter oilseed-rape line-cultivars Apex and Capitol from full flowering until near maturity as affected by the N fertilization rate (N0 and N160).…”

Nitrogen availability impacts oilseed rape (Brassica napus L.) plant water status and proline production efficiency under water-limited conditions

“…A number of traits are targets in an effort to significantly increase NUE such as improved rooting and greater root length density at depth (Svecnjak and Rengel 2006), prolonged N uptake mainly after flowering (Teakle et al 2008), optimized stem N storage and delayed senescence (Malagoli et al 2005), low seed protein and high seed oil contents (Nyikako 2003) and low leaf N loss (Malagoli et al 2005). The low NUE of oilseed rape has been significantly associated with the weak N remobilization that occurs in leaves during vegetative development (Dejoux et al 2000; Malagoli et al 2005) and is affected by senescence (Aufhammer et al 1994; Desclos et al 2009), mainly due to the loss of N-rich leaves (Schjoerring et al 1995; Dreccer et al 2000; Rossato et al 2001). …”

“…Pollution by excessive application of fertilizers and nitrate leaching is a source of environmental and economic concern in agriculture, and new goals are being set to reduce N supply while genetically improving the NUE of crops including oilseed rape (Aufhammer et al 1994; Barlóg and Grzebisz 2004; Masclaux-Daubresse et al 2008). However, lowering N input while optimizing yield may be counterproductive if it compromises how crop plants respond to environmental challenges, like high temperature and low water availability.…”

Nitrogen use efficiency in rapeseed. A review

“…phase sequentially, multiple overlapping source-sink situations are possible in rapeseed. This asynchrony between N source availability in old leaves and N requirements in seeds, along with incomplete protein hydrolyzation in the source organs, can lead to noteworthy N losses from fallen leaves (Aufhammer et al 1994;Diepenbrock 2000;Rossato et al 2001;Malagoli et al 2005a;Ulas et al 2013;Avice and Etienne 2014). Leaf senescence is therefore a critical stage at the intersection of N uptake and N remobilization in the reproductive organs (Schulte auf'm Erley et al 2007).…”