Azospirillum brasilense and Glomus intraradices co-inoculation stimulates growth and yield of cherry tomato under shadehouse conditions La co-inoculación con Azospirillum brasilense y Glomus intraradices estimula el crecimiento y rendimiento de tomate che

Resumen. Se evaluó la respuesta del cultivo de tomate cherry a la biofertilización con microorganismos benéficos bajo condiciones de casasombra. Las semillas fueron inoculadas y co-inoculadas con Azospirillum brasilense (Az) y/o Glomus intraradices (Gi); después del trasplante, las plántulas de seis tratamientos recibieron dos aplicaciones de una solución conteniendo Az + Gi, y fueron comparadas contra el tratamiento testigo que solo recibió fertilización tradicional (NPK). La co-inoculación de las semillas con A. brasilense y G. intraradices más dos aplicaciones de Az + Gi a los 15 y 30 días después del trasplante, incrementaron en promedio 6% la altura de plantas, 11% el área foliar, 10,5% la biomasa seca y 16% el rendimiento de tomate cherry en comparación con la fertilización tradicional. Palabras clave: Micorrizas arbusculares; PGPR; Biofertilizantes; Solanum lycopersicon. Abstract. The response of cherry tomato to biofertilization with beneficial microorganisms was evaluated under shadehouse conditions. Seeds were inoculated and/or co-inoculated with Azospirillum brasilense (Az) and/or Glomus intraradices (Gi). Thereafter, seedlings of six treatments received two applications of a suspension containing Az + Gi at 15 and 30 days after the transplant, and were compared against a non-inoculated treatment which only received conventional inorganic fertilization. Seed co-inoculation with A. brasilense and G. intraradices plus two applications of Az + Gi at 15 and 30 days after transplant increased on average 6% plant height, 11% leaf area, 10.5% dry biomass and 16% yield of cherry tomato in comparison to traditional fertilization

Soil solarization and sustainable agriculture

Pesticide treatments provide an effective control of soilborne pests in vegetable and fruit crops, but their toxicity to animals and people and residual toxicity in plants and soil, and high cost make their use hazardous and economically expensive. Moreover, actual environmental legislation is imposing severe restrictions on the use or the total withdrawal of most soil-applied pesticides. Therefore, an increasing emphasis has been placed on the use of nonchemical or pesticide-reduced control methods. Soil solarization is a nonpesticidal technique which kills a wide range of soil pathogens, nematodes, and weed seeds and seedlings through the high soil temperatures raised by placing plastic sheets on moist soil during periods of high ambient temperature. Direct thermal inactivation of target organisms was found to be the most important mechanism of solarization biocidal effect, contributed also by a heat-induced release of toxic volatile compounds and a shift of soil microflora to microorganisms antagonist of plant pathogens. Soil temperature and moisture are critical variables in solarization thermal effect, though the role of plastic film is also fundamental for the solarizing process, as it should increase soil temperature by allowing the passage of solar radiation while reducing energetic radiative and convective losses. Best solarizing properties were shown by low-density or vynilacetate- coextruded polyethylene formulations, but a wide range of plastic materials were documented as also suitable to soil solarization. Solar heating was normally reported to improve soil structure and increase soil content of soluble nutrients, particularly dissolved organic matter, inorganic nitrogen forms, and available cations, and shift composition and richness of soil microbial communities, with a marked increase of plant growth beneficial, plant pathogen antagonistic or root quick recolonizer microorganisms. As a consequence of these effects, soil solarization was largely documented to increase plant growth and crop yield and quality along more than two crop cycles. Most important fungal plant pathogenic species were found strongly suppressed by the solarizing treatment, as several studies documented an almost complete eradication of economically relevant pathogens, such as Fusarium spp., Phytophthora spp., Pythium spp., Sclerotium spp., Verticillium spp., and their related diseases in many vegetable and fruit crops and in different experimental conditions. Beneficial effects on fungal pathogens were stated to commonly last for about two growing seasons and also longer. Soil solarization demonstrated to be effective for the control of bacterial diseases caused by Agrobacterium spp., Clavibacter michiganensis and Erwinia amylovora, but failed to reduce incidence of tomato diseases caused by Pseudomonas solanacearum. Solarization was generally found less effective on phytoparasitic nematodes than on other organisms, due to their quicker soil recolonization compared to fungal pathogens and weeds, but field and greenhouse studies documented consistant reductions of root-knot severity and population densities of root-knot nematodes, Meloidogyne spp., as well as a satisfactory control of cyst-nematode species, such as Globodera rostochiensis and Heterodera carotae, and bulb nematode Ditylenchus dipsaci. Weeds were variously affected by solar heating, as annual species were generally found almost completely suppressed and perennial species more difficult to control, due to the occurrence deep propagules not exposed to lethal temperature. Residual effect of solarization on weeds was found much more pronounced than on nematodes and most fungal pathogens. Soil solarization may be perfect fit for all situations in which use of pesticides is restricted or completely banned, such as in organic production, or in farms located next to urban areas, or specialty crops with few labeled pesticides. Advantages of solarization also include economic convenience, as demonstrated by many comparative benefit/cost analyses, ease of use by growers, adaptability to many cropping systems, and a full integration with other control tools, which makes this technique perfectly compatible with principles of integrated pest management required by sustainable agriculture