Trichoderma spp. combination with fatty acid mixtures influence biocontrol activity, growth promotion yield nutritional quality of tomato and lettuce plant species -

Trichoderma spp. combination with fatty acid mixtures influence biocontrol activity, growth promotion yield nutritional quality of tomato and lettuce plant species

This research aimed at developing new biological formulations based on the combination of small microbial consortia containing two Trichoderma spp., with a medium–long chain fatty acids mixture (FAm). The bioactivity of these formulations was investigated on different vegetable crops in terms of biocontrol, growth promotion, yield and quality improvements. FAm application reduced Botrytis cinerea necrosis by up to 90% compared to the infected control plants and some of the assayed Trichoderma spp. + FAm combinations contained Rhizoctonia disease, reaching more than 90% reduction of tomato and lettuce plant mortality.

Fatty Acid Mixture Features (FAm)

The raw material is the by-product redundant from the production process for extra virgin olive oil. Olives are obtained from the Mediterranean region and must meet stringent quality standards and specifications to ensure conformity. The extraction and production processes of mixtures are purely physical processes, excluding the addition of chemical substances.

Extraction is the result of an ISO Quality

Controlled process of multi-stage distillation and fractionation. To ensure solubility in water the unsaturated carboxylic acids are formulated with potassium hydroxide to form potassium salts. The compatibility between FAm and the biological control agents was prepared using different concentrations of FAm (0.3%, 0.5%, 1%, 1.5%, 2%, 3%, 4%) in solid PDA the radial growth of Trichoderma harzianum M10 and Trichoderma virens GV41 on PDA enriched with increasing doses of Fam was compared to the radial growth of the same strains in un-amended PDA. FAm was applied at 0.3%, 0.5%, and 1%, while combined formulations were obtained by diluting Trichoderma spores in the FAm solutions. Two-week-old Lettuce (Lactuca sativa cv. Signorella) and tomato (Solanum lycopersicum cv. San Marzano) plants were transplanted onto 10 cm diameter pots containing Rhizoctonia solani-infested soil. Two days after transplanting, plants were drenched with 10 mL of single (either Trichoderma spp. or FAm) and combined components (Trichoderma spp. + FAm).

The seeds were allowed to germinate in the greenhouse under controlled temperature and humidity conditions. One week after emergence, 15 seedlings/treatment were watered with 5 mL of single and combined solutions (Trichoderma spp. + FAm). Successive applications were performed weekly, for a period of three weeks. Seedlings were then transplanted in soil under plastic tunnels and drenched with 50 mL of single and combined formulations of Trichoderma spp. and FAm (Trichoderma spp. + FAm). Subsequent applications were performed every 15 days for a further two months by watering each plant with 150 mL of the different formulations.

In Vitro and In Vivo FAm Biocontrol Activity

The radial growth of the foliar pathogen Botrytis cinerea on 3% and 4% FAm-containing medium was considerably reduced, compared to the control, 120 h post inoculation (hpi) showing a radial growth inhibition of 51% and 87.5%, respectively. No significant differences were detected comparing the effect of 3% and 4% FAm and thiophanatemethyl (TM) and comparing FAm concentration ranging to 0.3% and 2% with the control. On the other hand, all the assayed FAm concentrations were able to inhibit the growth of the soil-borne pathogen R. solani, reaching a 65% pathogen growth reduction at the lowest concentrations (0.3 and 0.5%). The bioactivity of FAm applications resulted comparable to those observed for commercial fungicide TM. 1% FAm was the most effective treatment in containing B. cinerea infection reducing necrosis by up to 90% compared to the infected control plants. The application M10 + FAm 0.5% and GV41 + FAm 1% did not allow the attack and development of the pathogen. A similar result was obtained when the two strains were used in combination with FAm 1% (M10 + GV41 + FAm 1%)

Growth Promotion Effect of Trichoderma spp. +FAm Combinations

Only the combination of M10 + GV41 + FAm 1% showed a positive effect on both stem and root dry weight. In fact, a 60% increase in root- and 30% increase in stem-dry weight was recorded compared to the untreated control plants. The combination of M10 + GV41 + FAm 1% resulted in increased tomato yield compared to the other treatments. A significant increase in fresh weight of lettuce heads was observed when the combinations M10 + FAm 0.3% and M10 + GV41 + FAm 0.5% were applied, with about a 25% increase compared to the control. M10 + FAm 0.5% increased kohlrabi fresh weight by 64%, 97% and 100% compared to M10, untreated control and FAm 0.5%, respectively

Conclusion

Combined biostimulant applications of Trichoderma spp. with fatty acid mixtures improved biocontrol activity, growth promotion and yield of treated plant species. These innovative bio-formulations were more effective than the treatment with the individual components (microbial or organic) not only in improving yield but also in producing a premium quality marketable vegetable with higher antioxidant content. The combination of specifically selected Trichoderma strains with natural bioactive substances represents a promising, efficient, and sustainable strategy for improving disease management and increasing yields in the context of eco-sustainable agriculture.

Reference:

Lanzuise, S., Manganiello, G., Guastaferro, V.M., Vincenzo, C., Vitaglione, P., Ferracane, R., Vecchi, A., Vinale, F., Kamau, S., Lorito, M. and Woo, S.L., 2022. Combined Biostimulant Applications of Trichoderma spp. with Fatty Acid Mixtures Improve Biocontrol Activity, Horticultural Crop Yield and Nutritional Quality. Agronomy, 12(2), p.275.