Effects of nitrogen rates on yield, yield components, and other related attributes of different rapeseed (Brassica napus L.) varieties

Abstract

Rapeseed is one of the most important oilseed crops in the world and, in Morocco, it may contribute to the improvement of food security in edible oils through developing performant cultivars and optimizing the crops management including nitrogen fertilization. The objective of this study was to evaluate the response of different Moroccan varieties to nitrogen application. Field trials were carried out at the experimental station of National School of Agriculture in Meknes, during two cropping seasons (2017–2018 and 2018–2019). Five varieties (“Narjisse”, “Moufida”, “Alia”, “Adila”, and “Lila”) were combined to different nitrogen rates (0, 30, 60, and 90 kg N ha−1). The experimental design adopted is a split split-plot with three replications, where nitrogen treatment was affected to main plot, variety to subplot, and year to sub-subplot. Results showed that dry matter, harvest index, oil content, seed yield per plant and yield components were significantly affected by nitrogen rates, with an upward trend in seed yield as the nitrogen rates increased. On average, seed yield increased by 50.33% for application of 90 kg N ha−1 compared to the control (without N fertilization). However, oil content declined from 41.08% to 37.81% with the increase of nitrogen level from 0 to 90 kg N ha−1. Additionally, for the other traits studied, the highest mean values were observed for 90 kg N ha−1, except harvest index which exhibited the greatest value for 60 kg N ha−1. Variation among the varieties was significantly large for all traits studied with a superiority of the variety “Alia” for seed yield per plant (9.82 g plant−1), number of pods per plant (151), and number of seeds per pod (24.05).

Optimizing nitrogen application rates for winter canola in Mississippi

“…A significant increase in N uptake was found by increasing N rates from 0 to 135 kg N ha −1 ; however, upon exceeding 135 kg N ha −1 , there was a stagnation in N concentration in biomass (Table 7). Previous studies have shown similar results, where N uptake concentration increased with N rates in canola (Chamorro et al., 2002; G. Jackson, 1999; Yahbi et al., 2022). For instance, Williams et al.…”

“…Likewise, previous research under different climatic conditions have observed similar results, where high N rates of 150 and 200 kg N ha −1 produced greater biomass (Ma et al, 2015). Yahbi et al (2022) reported similar results because of the positive correlation of N with biomass production in canola. Karamanos et al (2004) and Malhi et al (2007) have also shown that adequate N application during the vegetative growth stages of canola can lead to increased biomass production at later stages.…”

“…Previous studies have shown similar results, where N uptake concentration increased with N rates in canola (Chamorro et al, 2002;G. Jackson, 1999;Yahbi et al, 2022). For instance, Williams et al (2021) revealed that the N uptake was highest with 100 kg N ha −1 .…”

“…(2002) showed that increasing N rates reduced NUE, whereas Allen and Morgan (1972) and Yahbi et al. (2022) revealed that an increase in seed yield was observed with high N rates. Variable N rates can enhance the seed yield and increase nutrient use efficiency to a certain extent, while the remaining residual N is lost to the environment causing perturbations and soil degradability (Ma et al., 2019).…”

Proximate Composition, Physicochemical, and Lipids Profiling and Elemental Profiling of Rapeseed (Brassica napus L.) and Sunflower (Helianthus annuus L.) Grown in Morocco

“…Currently, rapeseed is gaining importance as one of the main components of the oilseeds sector in Morocco. According to the latest available data, both oilseed crops (sunflower and rapeseed) are cultivated on an area of roughly 36,000 ha, with a total production of nearly 39,000 tons [ 13 ].…”