The genus Trichoderma is widely used in agriculture as a biological agent and biofertilizer, enhancing crop yield and quality. However, its use in hydroponic systems is limited. This study evaluated the potential of Trichoderma asperellum as a growth promoter for lettuce (Lactuca sativa L.) cv. Starfighter RZ in a floating-root hydroponic system (FHS). T. asperellum strains (TaMFP1 and TaMFP2) were isolated from soil and identified morphologically and molecularly. The experiment used a completely randomized design with the following four treatments (n = 4): root spraying with TaMFP1, TaMFP2, T. harzianum (Trichospore^®), and uninoculated plants (control). After 30 days, morphological, biochemical, and quality parameters were analyzed. All Trichoderma treatments significantly increased plant height (19.0%), root length (25.7%), total fresh biomass (76.4%), total dry biomass (82.63%), and number of leaves (18.18%). The nitrate levels in leaves were unaffected by TaMFP1 and TaMFP2, while Trichospore^® reduced the nitrate content by 24.94%. The foliar nitrogen content increased with specific treatments, though the phosphorus and magnesium levels decreased. Visual quality traits, including appearance and firmness, remained unchanged. T. asperellum strains TaMFP1 and TaMFP2 enhanced vegetative growth without compromising quality, demonstrating their potential as sustainable tools for hydroponic lettuce production in controlled environments.

The study evaluated the effect of Bacillus thuringiensis (Bt) and Trichoderma asperellum (Ta) as biostimulants in hydroponically grown tendril pea (Pisum sativum) microgreens. A completely randomized experimental design was conducted under controlled conditions; the study included the root pea-spraying treatment with Bt, Ta, and their combination, alongside a non-inoculated control. The results showed that treatments with Ta significantly enhanced growth parameters, such as stem length and diameter, stipular leaf area, and fresh weight of the microgreens. Specifically, fresh biomass increased by 140% and dry biomass by 80% with Ta compared to the control, while combined treatment with Bt and Ta reduced nitrates by 39.6%. Bt and Bt + Ta increased chlorophyll b and carotenoids contents, suggesting improved photosynthetic activity. No significant differences in visual appearance were observed. In conclusion, the application of Ta and Bt can enhance tendril pea microgreens’ yield and certain biochemical (chlorophyll b and carotenoids) qualities without affecting their visual quality, supporting the application of these microorganisms as biostimulants. These findings underscore the potential to scale these treatments in commercial hydroponic systems, offering a sustainable approach to optimizing the production of this emerging crop type.

Using beneficial microorganisms as biostimulants is a promising strategy to enhance crop growth and productivity in hydroponic systems. Trichoderma asperellum has demonstrated plant growth-promoting effects in soil cultivation; however, its efficacy in hydroponic Deep-Water Culture (DWC) systems remains underexplored. This research evaluated the effect of T. asperellum strains TaMFP1 and TaMFP2 on the growth, nutrient uptake, and visual quality of hydroponically grown spinach cv. Stella Plus F-1 (Spinacia oleracea L.). A randomized complete design was used, comparing inoculated plants with a control and a commercial Trichoderma harzianum product. After 28 days, the results showed that T. asperellum significantly increased plant height (23.1%), collar diameter (21.8%), root length (39.6%), leaf area (22.0%), number of leaves (18.05), and fresh biomass accumulation (23.5%) compared to non-inoculated plants. Furthermore, inoculation with TaMFP1 improved spinach yield by 34.5%, while nutrient analysis indicated enhanced phosphorus and calcium uptake. No significant changes were observed in photosynthetic pigment concentrations, and the visual quality of the harvested spinach was unaffected. These findings highlight the potential of T. asperellum as a sustainable biostimulant in hydroponic spinach production. These results contribute to developing beneficial microorganism-based strategies to enhance the sustainability of hydroponic agriculture.

Introduction. The Bacillus genus has been used as a biostimulant with positive effects on crop yield and quality. However, there are few studies on its application in microgreens. Objective. To evaluate the effect of Bacillus subtilis (BsC4 and BsPC) and Bacillus thuringiensis (Bt24) as biostimulants on the germination and growth of red cabbage (Brassica oleracea var. capitata) and kale (Brassica oleracea var. sabellica) microgreens under controlled environmental conditions. Materials and methods. The study was conducted at the Universidad Autónoma de Chihuahua, Mexico, in 2023. Four treatments were assessed: Bt24, BsC4, BsPC, and seedlings without microorganisms (control) on red cabbage and kale seeds, under a completely randomized design (n = 5). Germination was monitored in the first trial, and microgreens development was assessed in the second. After 15 days, morphological variables, photosynthetic pigments, nitrate content, quality, and yield were measured. Data were analyzed using analysis of variance and Tukey’s tests (p < 0.05). Results. For kale, Bt24 improved germination speed (31.17 %) and reduced germination time (4.61 %), with no significant effect on red cabbage. In kale, yield increased (62.60 %) with Bt24, particularly in fresh biomass (63.3 %) and cotyledon area (61.57 %). In cabbage, BsC4 increased yield (44.31 %) and improved fresh biomass (42.21 %) and cotyledon area (50.57 %). Nitrate content was highest in kale with BsPC (138.30 %) and in red cabbage with Bt24 (65.14 %), while remaining within safe consumption limits. For visual quality, both crops achieved the “Good” and “Excellent” categories, with no differences between treatments. Conclusions. B. thuringiensis and B. subtilis could be used as growth biostimulants for cabbage and kale microgreens, offering a promising approach to optimize microgreen production under controlled environmental conditions.

One of the great challenges that apple producers face is to substantially improve the quality of fruit, including after harvest. A balanced and timely supply of calcium (Ca) during growth and in the post-harvest stage is considered a technique that could improve shelf life and fruit quality; thus calcium plays a key role during post-harvest, with calcium carbonate and calcium sulphate being an alternative of foliar spraying. The study was carried out on ‘Top Red’ and ‘Golden Delicious’ apple cultivars, in a randomized complete block design with 13 treatments (referring to different commercial presentations of calcium) and 6 repetitions; 8 foliar sprays were applied weekly, from June 22 until harvest; ‘Top Red’ (151 days after full flowering, DDCF) and ‘Golden Delicious’ (145 DDCF) fruit were evaluated in regard with fruit traits (diameter, weight and colour) and maturity (pulp firmness, total soluble solids, titratable acidity and sugar acidity ratio). In ‘Top Red’ cv., calcium carbonate presented the best results, with intermediate to high quality apple fruit, while for cv. ‘Golden Delicious’ the best results were obtained with calcium sulphate, which increased fruits’ diameter, weight, colour and titratable acidity. Even more, of the products evaluated, CaCO3 and CaSO4 had the lowest costs, and can be considered as good alternatives of foliar calcium supplement applied in order to preserve the quality of the apple during post-harvest. ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

The cultivation of apple (Malus domestica (Borkh.) Borkh.) holds significant global importance due to their flavor and nutritional value. In Mexico, Chihuahua leads in production, yet the response of the Golden Glory variety to biostimulants remains unstudied. This study aimed to evaluate the effect of biostimulants on fruit quality in Golden Glory apple. Conducted in Namiquipa, Chihuahua, during the 2023 season, the study employed randomized experimental design with treatments (amino acids, algae, fulvic acids, and a control) spraying weekly from flowering to near harvest. Fruit characteristics were evaluated 90 days post-initial treatment. Amino acids significantly improve fruit weight (27.98 %), diameters (8.41 % polar and 9.28 % equatorial), color (178.8 %), and total soluble solids (TSS;5.72 %), while reducing malic acid content and enhancing TSS/AT ratio by 23.21 %, with no impact firmness. Fruit quality met marketing standards. Seaweed and fulvic acids treatment showed no significant improvement parameters. These results underscore amino acids ‘efficacy in enhancing 'Golden Glory' apples quality. Keywords: amino acids, seaweed, fulvic acids, Malus domestica Borkh