Root‐growth characteristics contributing to genotypic variation in nitrogen efficiency of oilseed rape

Abstract

A 3-year field experiment was carried out to determine the significance of root-growth characteristics contributing to N-uptake efficiency of two oilseed rape (Brassica napus L.) cultivars differing in N efficiency. Two N treatments were applied, and the core and minirhizotron techniques were used to study root-length density and number of living roots, respectively. Fertilizer-N supply increased shoot dry matter, grain yield, total N uptake, and total soil N min contents particularly in the top soil. Although significant differences occurred in all parameters between years, the interactions between years and cultivars were mostly not significant. Compared to cv. Capitol, the N-efficient cv. Apex was characterized by a higher grain yield at N0 and a higher N uptake during reproductive growth. This genotype also had a higher root-length density and more living fine roots particularly in the topsoil layer. Root growth of this genotype was especially high from beginning of shooting to beginning of flowering, while shoot growth and N uptake during vegetative growth were comparatively low. Our results suggest that N-efficient cultivars can be characterized by a high investment in root growth during the vegetative stage with a comparatively slow shoot growth and N-uptake rate until beginning of flowering, which, however, continues during reproductive growth. High root production only during reproductive growth seems to be less effective to achieve high N efficiency, because this may lead to a shortage of assimilates for seed filling. High root-length density at vegetative stages may thus be advantageous for N uptake and reproductive growth and could be a useful morphological character for the selection and breeding of N-efficient cultivars.

Growth, root morphology and leaf physiology of watermelon as affected by various rates and forms of nitrogen in the hydroponic system

“…In agreement with several studies (Wilcox et al, 1985;Sattelmacher et al, 1990;Schulte Auf'm Erley et al, 2007;Ulas et al, 2012;2013;2019), our results clearly demonstrated that nitrogen rates and forms have pronounced effects on the shoot and root growth of watermelon. Moreover, our results are highly corroborating with the results of cereal crop experiments which indicated that the best growth was obtained when a mixture of both N-Forms (ammonium and nitrate) compared to sole nitrate was supplied to the plants (Hageman, 1984;Huffman, 1989).…”

Segmentation of roots in soil with U-Net

“…Plant Methods *Correspondence: ags@di.ku.dk 2 Department of Computer Science, University of Copenhagen, Universitetsparken 1, 2100 Copenhagen Ø, Denmark Full list of author information is available at the end of the article manually using the line-intersect method where the number of roots crossing a line in a grid is counted and correlated to total root length [18,19] or normalised to the total length of grid line [20]. The line-intersect method was originally developed for washed roots but is now also used in rhizotron studies where a grid is either directly superimposed on the soil-rhizotron interface [21,22] or indirectly on recorded images [23,24]. The technique is arduous and has been reported to take 20 min per metre of grid line in minirhizotron studies [25].…”

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

“…Capitol revealed that genotypic variation in N efficiency was at least partially based on a higher biomass allocation efficiency to the grains (Figure 3). However, N efficiency of winter oilseed-rape line-cultivars has been primarily attributed to high N uptake efficiency (NUPT), which mainly results from maintained N uptake during reproductive growth [9,10,12]. Under N-limiting conditions (N0) the N-efficient cv.…”