The main goal of our study was to find an optimal combination of tested factors to achieve lettuce rich in bioactive compounds sustaining its pleasant taste. We examined three red and three green cultivars in a greenhouse using two microbiological fertilisers (EM Aktiv and Vital Tricho), and their combination. Plants were grown in three consecutive growing seasons (autumn, winter, and spring). Lactones accumulated in autumn, whereas phenolics’ concentration rose during winter. Red cultivars showed higher phenolics and lactone content, where chicoric acid and luteolin-7-glucoside were the most abundant in the ‘Gaugin’ winter trial. Lactucopicrin was the predominant lactone among tested cultivars with the highest value in the red cultivar ‘Carmesi’. Solely applicated, the fertiliser EM Aktiv and Vital Tricho led to significantly higher phenolic acid and dihydrolactucopicrin content, while combined, there were notably increased levels of all detected lactones. Application of single fertilisers had no effect on flavonoid content, while the combination even reduced it. A sensory analysis showed a negative correlation between overall taste and total sesquiterpene lactones, lactucopicrin, caffeoylmalic, and chlorogenic acid, indicating a less bitter taste with decreasing content of these compounds. Our findings indicate that the cultivar, fertiliser, and growing season jointly affected all of the tested parameters, highlighting the differences in the application of EM Aktiv, Vital Tricho, and their combination.

This study assessed the impact of biofertilisers on primary and secondary (specialised) metabolites in six lettuce cultivars (‘Kiribati’, ‘Murai’, ‘Aquino’, ‘Gaugin’, ‘Aleppo’, and ‘Carmesi’) grown in anthropogenic soil during an autumn greenhouse experiment. Four treatments were tested: control (no fertilisation), effective microorganisms (EM), Trichoderma, and their combination. Red cultivars showed higher total antioxidant capacity (TAC) and total phenolic content (TPC), with red Lollo ‘Carmesi’ having the highest TAC, TPC, carotenoids, total soluble solids, sweetness index, and sugars. Red Oak ‘Murai’ exhibited the highest chlorophyll b and total chlorophyll, while green cultivars ‘Kiribati’ and ‘Aquino’ excelled in chlorophyll a and overall taste, respectively. Biofertilisers did not affect TAC or most chlorophyll types but increased TPC (EM by 18.6% and combined treatment by 19.6%) and chlorophyll a (EM by 28.6% and Trichoderma by 23.8%). Combined fertilisers improved taste with reduced glucose and fructose content and sweetness index, though sucrose remained unchanged compared to the control. Major organic acids (malic, citric, and tartaric) were most abundant in ‘Murai’ and ‘Kiribati’, unaffected by treatments. Phenolics content peaked in ‘Murai’ and ‘Carmesi’, characterised by chicoric and chlorogenic acid, caffeoylquinic acid glucoside, and flavonoids (quercetin derivatives, kaempferol); biofertilisers mainly influenced gallic acid, while kaempferol was affected by all biofertilisers and increased in the range of 12.5–25%. The key sesquiterpene lactones identified were lactucin, lactucopicrin-15-oxalate, and 11β,13-dihydrolactucin. The content of sesquiterpene lactones analysed in this study increased significantly, especially with EM treatment (14.7–185.7%) and combined fertilisers (12.5–128.6%), highlighting the lactone-rich cultivars ‘Carmesi’ and ‘Gaugin’. Red cultivars ‘Carmesi’ and ‘Murai’ exhibited the most favourable phytochemical profiles, suitable for cultivation and processing of quality-based products. In contrast, the green cultivar ‘Aquino’ received the highest sensory scores, delivering the most appealing overall taste despite its lower metabolite content. EM treatment and combined fertilisers are recommended for increasing chlorophyll a, myo-inositol, TSS, propionic acid, TPC, kaempferol, and major lactones under greenhouse autumn conditions.

A multi-factor analysis of cultivar, biofertiliser, and growing season was conducted to optimise lettuce agronomic and quality traits in diverse soil conditions. The goal was to identify soil differences and offer practical recommendations to improve lettuce traits and quality for farmers and the processing industry. The study employed a complete block design with four treatments, three involving biofertilisers, applied to six lettuce cultivars grown in two contrasting soil types- Mollic Gleysol (Calcaric)-GL and Hortic Anthrosol (Terric, Transportic)-AT, across three consecutive greenhouse seasons (autumn, winter, and spring). Biofertilisers were applied to the soil before transplanting and foliarly during the growing cycle, with four of the following treatments: control (no fertilisation), a fertiliser containing beneficial microorganisms, a Trichoderma-based fertiliser, and a combination of both. In GL soil, all biofertiliser treatments increased rosette height, leaf number, and stem length, whereas in AT soil, all morphological parameters declined significantly. The green cultivars ‘Aquino’ and ‘Kiribati’ showed superior morphological performance, particularly in spring and winter. Rosette fresh weight, a key indicator of plant biomass, reached 236.4 g in ‘Aquino’ grown in GL soil, and 208.6 g in ‘Kiribati’ grown in AT soil. Dualex™ leaf sensor measurement indicated that ‘Aquino’ exhibited the highest nitrogen balance index (NBI), while the red cultivar ‘Gaugin’ recorded the highest chlorophyll, flavonoid, and anthocyanin contents. Combined fertilisers increased NBI by 6.3% and chlorophyll by 6.8% in GL soil. Trichoderma fertiliser alone raised NBI by 6.8% in GL soil, whereas in AT soil, plants accumulated more flavonoids and anthocyanins (by 9.2% and 8.5%). Optical parameters were highest in autumn. The three-factor experiment demonstrated that cultivar, biofertiliser, and growing season significantly influenced the majority of measured traits. Correlation analysis revealed that rosette fresh weight was positively associated with NBI but negatively correlated with quality-related traits. Based on these findings, cultivars ‘Aquino’, ‘Kiribati’, and ‘Gaugin’ are recommended for both farmers and the processing industry to improve lettuce production quantity and quality. Overall, cultivar, biofertiliser, and season strongly influenced the measured parameters, underscoring the importance of tailoring biofertiliser application to soil type and season to achieve optimal production outcomes.

Five lettuce cultivars ('Kiribati', 'Tourbillon', 'Carmesi', 'Lianabel', and 'Biondonna') were grown in the open-field experiment during the summer of 2018. The aim was to find the optimal summer lettuce cultivar according to morphological and production parameters, suitable for the fresh market and food industry processing by applying the MABAC (Multi-Attributive Border Approximation Area Comparison) method. The correlation analysis was carried out to reduce the number of criteria that have high coefficient values and a double influence on the ranking results. The study involved five alternatives (cultivars) and five different criteria regarding morphological parameters (rosette height, rosette diameter, rosette fresh weight, number of leaves, and stem height). Weight coefficients were determined using the AHP (Analytic Hierarchy Process) method while the stability of the obtained ranking list was determined by applying sensitive analysis through six scenarios. According to the selected criteria, the obtained results showed that the green cultivar 'Tourbillon' has the best results, while the least favorable results were obtained by the red cultivar 'Carmesi'. Furthermore, this study tends to facilitate cultivar selection by farmers to avoid economic losses and sustain the required quantity and quality standard demands for the fresh product and food industry market.

Lettuce (Lactuca sativa L.) is an annual leafy vegetable crop from the Asteraceae family with the possibility to grow all year round. Two lettuce cultivars (red 'Murai' and green 'Aleppo') were cultivated in a greenhouse using two biofertilizers (a mixture of different effective microorganisms and Trichoderma spp. fertilizer), and their combination, during three consecutive growing seasons. This study aimed to find the optimal combination of fertilization treatments and growing seasons depending on different production criteria, using a multi-criteria decision-making (MCDM) method, Measurement of Alternatives and Ranking according to COmpromise Solution (MARCOS). A total number of 12 lettuce production models (alternatives) were proposed regarding fertilization treatments and planting dates. The study analyzed 12 criteria, which were divided into three groups: quantity, quality, and economic criteria. Weight coefficients were determined using the Analytic Hierarchy Process (AHP) method while, the stability of the obtained ranking list was investigated by applying comparative analysis using four other MCDM methods, as well as by performing sensitivity analysis through four scenarios. Cultivar 'Murai' showed the best results in the winter growing season with the application of Trichoderma spp. fertilizer, while cultivar 'Aleppo' in the spring with the combined fertilizers (effective microorganisms + Trichoderma spp). This study supports farmers and agricultural companies in optimizing planting schedules and biofertilizer selectiontailored to specific cultivars, integrating quantity, quality, and economic criteria to enhance productivity and sustainability. Furthermore, it reveals the significant role of cultivar choice in optimizing biofertilizer type and growing season selection for lettuce production, demonstrating the MARCOS method’s robustness as a decision-support tool in agricultural planning and management.

Although greenhouse vegetable production is rapidly shifting toward innovative soilless systems, soil-based conventional cultivation still dominates globally. This production system faces growing pressure to transition to sustainable practices. However, introducing biofertilisers into intensive systems often yields inconsistent results. Specifically, their effects on different lettuce traits vary due to complex relationships between genotype, biofertiliser, environmental conditions, and market demands. Single-parameter evaluations fail to balance conflicting criteria, necessitating multi-criteria decision-making (MCDM) methods for selecting optimal choices. This study aims to overcome these inconsistencies through an integrated fuzzy MCDM-based optimisation model. Three lettuce cultivars (‘Carmesi’, ‘Aquino’, and ‘Gaugin’) were grown in an unheated Surčin (Serbia) greenhouse during a 58-day autumn experiment using a complete block design. Four treatments were applied: a control (without fertilisation), effective microorganisms, a Trichoderma-based fertiliser, and their combination. Biofertilisers were applied before transplanting and four times foliarly during the vegetation period via battery sprayer. This defined 12 production models (cultivar–fertiliser pairs), evaluated across 10 criteria: agronomic (core ratio, number of leaves), quality (nitrate content, total antioxidant capacity, total soluble solids, and chlorogenic acid), sensory (overall taste, overall quality), and economic (total variable costs, total income). Four decision-making experts from the Faculty of Agriculture and the ready-to-eat salad industry assessed weighting coefficients using the fuzzy PIPRECIA (PIvot Pairwise RElative Criteria Importance Assessment) method. The fuzzy MARCOS (Measurement Alternatives and Ranking according to COmpromise Solution) method was used to rank the alternatives. To confirm the stability of the obtained ranking with the fuzzy MARCOS method, we performed sensitivity analysis through 20 different scenarios. Applied fuzzy methods identified alternative A11—‘Aquino’ cultivar with combined biofertilisers—as the best-ranked option, followed by A6 and A7. This study validates fuzzy PIPRECIA and fuzzy MARCOS as effective tools for optimising lettuce production models. They support farmers in selecting the most favourable solution based on multiple criteria, aiding the shift from mineral fertilisers to sustainable biofertiliser-based systems in intensive production—especially helpful for producers making this transition.