Introduction: Canola (Brassica napus L.) is one of the most important oilseed crops worldwide, valued for its high oil content and nutritional quality. Cultivating canola in cold regions poses challenges due to environmental stresses such as low temperatures and short growing seasons. Identifying high-yielding and cold-tolerant canola cultivars is essential for optimizing production in these areas. This study aimed to evaluate 24 canola cultivars under cold climatic conditions over two crop years (2021–2023) to determine the most suitable genotypes based on agronomic traits, yield components, and oil content. The findings will assist farmers and breeders in selecting superior cultivars for cold regions, ultimately enhancing canola productivity and oil quality.
Materials and Methods: The experiment was conducted using a completely randomized block design (CRBD) with four replications over two growing seasons. Twenty-four canola cultivars were assessed for key traits, including flowering period, length of growing season, plant height, number of pods per plant, number of seeds per pod, 1000-seed weight, oil content, and seed yield. Data were analyzed using ANOVA, with mean comparisons conducted through LSD tests. To explore relationships between grain yield and other traits, correlation analysis was performed. Cluster analysis, utilizing the heatmap method, grouped genotypes and characteristics. Additionally, principal component analysis (PCA) and biplot visualization were employed to identify superior cultivars based on multiple traits. Data analysis from the experiment was conducted using SAS 9.4 software. Additionally, cluster analysis with Ward's method, factor analysis, and a biplot based on principal component analysis were performed using R software.
Results and Discussion: The results of the combined data analysis showed that the difference between the two experimental years was significant only in terms of grain yield. There was a significant difference between the studied varieties in terms of length of growing season, plant height, number of pods per plant, number of seeds per pod, 1000-seed weight, and oil content. The interaction of year with variety was also significant, but only in terms of grain yield. The results indicated that the Parade cultivar demonstrated exceptional performance in several areas, including growth period length, plant height, seeds per plant, seeds per pod, and 1000-kernel weight. Among the cultivars tested, Coctall, Cwc, Alice, Parade, and VDH8003-98 produced the highest grain yields in both years. Additionally, Regent * Cobra recorded the highest seed oil percentage, making it a promising candidate for oil production. A positive and significant correlation was found between seed yield and two critical yield components: the number of pods per plant and the number of seeds per pod. This indicates that selecting cultivars with a higher number of pods and seeds can improve overall yield potential. The heatmap clustering analysis divided the 24 genotypes into three distinct categories and grouped the traits into four categories: Group 1 (High-yielding genotypes): Parade, Cwc, Eurol, Orient, DP.948, PF.7045/91, and Regent * Cobra. These cultivars exhibited exceptional yield and yield-related characteristics. Groups 2 and 3 consisted of genotypes that exhibited moderate to low performance in the examined traits. PCA identified two primary factors accounting for 54.7% of the overall variance. The biplot analysis demonstrated that Parade, Olara, DP.948, Alice, VDH8003-98, Coctall, and Cwc were situated in the most advantageous area, signifying their well-rounded performance in terms of yield and its components.
Conclusion: This study identified Parade and Cwc as the top-performing canola cultivars based on yield and yield-related traits, making them suitable for cultivation in cold regions. Additionally, Regent * Cobra was noted for its high oil content, which is essential for oil production. The findings highlight the importance of selecting cold-adapted canola cultivars to maximize both productivity and oil quality in challenging environments. It is recommended to cultivate the Parade and Cwc varieties in the cold regions of the northwest of the country to achieve high yields, and the Regent*Cobra variety for oil production.