Nitrogen Use Efficiency in Parent vs. Hybrid Canola under Varying Nitrogen Availabilities

Abstract

Improving nitrogen use efficiency (NUE) is essential for sustainable agriculture, especially in high-N-demanding crops such as canola (Brassica napus). While advancements in above-ground agronomic practices have improved NUE, research on soil and below-ground processes are limited. Plant NUE—and its components, N uptake efficiency (NUpE), and N utilization efficiency (NUtE)—can be further improved by exploring crop variety and soil N cycling. Canola parental genotypes (NAM-0 and NAM-17) and hybrids (H151857 and H151816) were grown on a dark brown chernozem in Saskatchewan, Canada. Soil and plant samples were collected at the 5–6 leaf stage and flowering, and seeds were collected at harvest maturity. Soil N cycling varied with phenotypic stage, with higher potential ammonium oxidation rates at the 5–6 leaf stage and higher urease activity at flowering. Seed N uptake was higher under higher urea-N rates, while the converse was true for NUE metrics. Hybrids had higher yield, seed N uptake, NUtE, and NUE, with higher NUE potentially owing to higher NUtE at flowering, which led to higher yield and seed N allocation. Soil N cycling and soil N concentrations correlated for improved canola NUE, revealing below-ground breeding targets. Future studies should consider multiple root characteristics, including rhizosphere microbial N cycling, root exudates, and root system architecture, to determine the below-ground dynamics of plant NUE.

Deciphering the Genetic Basis of Root and Biomass Traits in Rapeseed (Brassica napus L.) through the Integration of GWAS and RNA-Seq under Nitrogen Stress

“…Root system architecture (RSA) plays a critical role in N acquisition, both in terms of absorption capacity and soil exploration potential. A deeper understanding of how the RSA adapts to N availability seems to be a potential lever for optimizing N acquisition [ 10 , 11 , 12 ]. As a primary step, determining the key traits underpinning genotype variability and RSA adaptability to N availability is required.…”

Oilseed Rape Cultivars Show Diversity of Root Morphologies with the Potential for Better Capture of Nitrogen

“…Thus, improving NUE is essential to ensure the environmental and economic sustainability of that crop production [12,13]. Breeding programs are largely focusing on NUtE in above-ground organs [14][15][16] and research on soil and below-ground processes are limited [17]. Yet, the root organ holds potential for NUpE improvement [18,19].…”

Recent trends in nitrogen cycle and eco-efficient nitrogen management strategies in aerobic rice system

“…Improvements in NUE under aerobic rice systems and other non-N 2 -fixing crops are required to fulfill the future food requirements of the projected inflation in the population via improved and modified N-use efficient varieties along with other crops, irrigation, and fertilizer management practices ( Mboyerwa et al, 2021 ). Management practices that focus on improving plant N uptake and NUE involve irrigation methods, fertilizer input management, crop variety management in terms of water and NUE, plant N uptake management, use of controlled-release N fertilizers, use of NIs and urease inhibitors for synthetic N fertilizers, and other agronomic integrative crop management approaches ( Pan et al, 2017 ; Gweyi-Onyango et al, 2021 ; Williams et al, 2021 ; Ebbisa, 2022 ; Ma X. et al, 2022 ). Several studies regarding NUE have demonstrated that it is majorly associated with the type and method of fertilizer inputs, irrigation methods, availability of soil N, and plant N uptake ( Ye et al, 2013 ; Rawal et al, 2022 ).…”