Multicriteria Analysis of the Effect of Organic Growth Stimulants on Canola

Background and Objectives: Canola (Brassica napus L.) is one of the most important oilseed crops, and its production in arid and semi-arid regions is increasingly constrained by water scarcity and drought stress. Improving water productivity and yield stability under limited irrigation conditions is therefore essential for sustainable canola production. Biostimulants as organic growth stimulants have recently gained attention as an eco-friendly strategy to mitigate drought-induced yield losses. In addition, increasing evidence suggests that the effectiveness of biostimulants is closely related to environmental conditions and plant physiological status, particularly under water-limited scenarios. Under drought stress, these compounds can enhance root development, improve nutrient uptake efficiency, and regulate osmotic balance, leading to better maintenance of photosynthetic activity and yield formation. However, their responses are often variable depending on the type of biostimulant, intensity of water stress, and crop genotype, which makes it necessary to evaluate their performance under field conditions using integrated approaches.
Materials and Methods: This study aimed to evaluate the effects of organic growth stimulants on seed yield, seed oil content, and water productivity of canola under normal irrigation and water stress conditions, and to rank treatments using the VIKOR multi-criteria decision-making method. A split-plot experiment based on a randomized complete block design with three replications was conducted over two growing seasons at the Moghan Agricultural Research Station. Irrigation treatments (main plots) included normal irrigation and water stress, while sub-plots consisted of foliar application of amino acids, humic acid, fulvic acid, seaweed extract, and an untreated control. In addition, a Monte Carlo simulation approach with 2000 iterations was applied to assess the stability of the VIKOR ranking under uncertainty in criterion weights.
Results: Mean comparison results showed that water stress reduced seed yield by 5.4%, seed oil content by 9.2%, and water productivity by 4.5% compared with normal irrigation. In contrast, application of growth stimulants increased seed yield by 10.47–15.03%, seed oil content by 5.76–11.26%, and water productivity by 9.84–17.21% compared with the control. Among treatments, amino acid under water stress produced the highest seed yield (3703 kg ha⁻¹) and water productivity (1.79 kg m⁻³), whereas humic acid under normal irrigation resulted in the highest seed yield (3844 kg ha⁻¹) and seed oil content (43.9%). VIKOR analysis indicated that amino acid under water stress had the lowest Q value (Q = 0.022), ranking first as the most desirable compromise solution. Monte Carlo sensitivity analysis further confirmed the robustness of this treatment, which retained the first rank in 82.65% of simulation scenarios.
Conclusion: Overall, the results demonstrate that drought stress significantly reduces canola yield and quality parameters, while organic growth stimulants effectively mitigate these negative effects. In particular, amino acid application under water stress conditions provided the best trade-off among yield, quality, and water productivity, showing both superior performance and high ranking stability. Therefore, integrating organic biostimulants with deficit irrigation management can be considered an effective strategy for improving canola productivity and sustainability in semi-arid environments. Moreover, the multi-criteria decision-making results highlighted that relying solely on individual performance indicators may lead to suboptimal selection of treatments, as different stimulants showed contrasting advantages across yield, oil content, and water productivity. The VIKOR analysis provided a more balanced and integrated ranking by simultaneously considering all evaluated criteria, thereby identifying compromise solutions that best satisfy the conflicting objectives of productivity and resource efficiency.