Evaluación de paecilomyces variotii pae10773 como agente de control biologico (acb) y hongo promotor del crecimiento de plantas (hpcp)

Abstract

By 2050, is expected an increase in the world population to reach 10 billion. In addition, climate change aggravates such important problems for agricultural production as salinity and drought. This results in a reduction of agronomically suitable for cultivation lands. All of this, leads us to a scenario of food deficit, giving rise to increase crop yields. For this, agrochemicals has traditionally been used. However, its indiscriminate use has generated the appearance of environmental problems (environmental pollution, biodiversity loss, effects on the fertility of farmland, etc.) and human health problems (reduced fertility, hypertension problems or development of different types of cancer, etc.). The growing environmental awareness requires the use of sustainable agricultural techniques. Incorporating microorganisms in crop production is the most promising strategy for maintaining agricultural productivity and reducing the use of inorganic fertilizers and pesticides. This Thesis will focus on the use of microbial formulations as a viable alternative to chemical products inputs. Therefore, the general objective is development a new microbial formulation (Paecilomyces variotii) for use in agriculture, both for plant growth promoting and diseases protection. For this, three independent works were carried out: Chapter 1. Paecilomyces and its importance in the biological control of agricultural pests and diseases. A review of the genus Paecilomyces, composed by species with high growth rates and spore production in numerous substrates ensures the production of viable, affordable and efficient commercial formulations for agricultural use. Paecilomyces is mainly known for its nematophagous capacity, but it has also been described as an insect parasite and a biological control agent of several phytopathogenic fungi and bacteria through different mechanisms of action. This review includes all the information on the genus Paecilomyces as a biological control agent for pests and diseases. Chapter 2. Paecilomyces variotii as a plant-growth promoter in horticulture. To do this, P. variotii was tested to determine the effect on the growth promotion of tomato and pepper seeds and seedlings. The evaluation was carried out through laboratory tests and tests under nursery and greenhouse conditions. Our isolate showed a high ability to produce siderophores and IAA, but low ability to solubilize phosphorus. In addition, its application on horticultural seeds improved the values of germination percentage, vigor and length of roots and shoots. P. variotii applications resulted in improved most of the growth parameters evaluated, for both horticultural crops, with the best results in the development of pepper seedlings. The application of a higher dose of P. variotii improved most of the morphological parameters and the DQI value in tomato seedlings and plants. The establishment of the fungus as an endophyte in the root allowed to continue its effects after transplantation without any additional application. Chapter 3. Biocontrol effect of Paecilomyces variotii against fungal plant diseases. The in vitro and in vivo antagonistic capacity of P. variotii against seven phytopathogens, and its compatibility with 24 commercial fungicides was analyzed. P. variotii was applied to the following pathosystems: B. cinerea, M. melonis, and P. aphanidermatum - melon; F. solani and P. xanthii - zucchini; Sclerotinia sclerotiorum - pepper; and R. solani - tomato. The results showed high reductions in the disease severity index by 78% and 76%, for M. melonis and P. xanthii, respectively. The reduction in the other pathosystems ranged from 29% to 44%. However, application of metabolites did not cause any significant effect on mycelial growth, apart from F. solani, in which up to 12% inhibition was observed in vitro when the extract was applied at a concentration of 15% in the medium. Finally, P. variotii was compatible with most of the tested fungicides. Of the 24 products studied at the maximum authorized dose, 6 acted as fungicides, 4 as fungistatics, and the remaining showed inhibition rates ranging from 18.2% to 95.8%. Therefore, we can conclude that P. variotii is a potential agent for both plant promotion and biological control against diseases, thus it should be integrated into modern fertigation and disease management strategies.