Los hongos micorrícicos, una alternativa agroecológica para el manejo de las variedades tradicionales de tomate en canarias

Abstract

Tomato crops have decreased considerably in the Canary Islands over the last few years. Among other reasons, it is due to parasite and pathogen incidences, use of poor quality irrigation water, the cultivation in more competitive regions and a lack of modern infrastructures. These circumstances lead to a reduction in the production and profitability. Against this background, the cultivation of landraces could be an alternative because they are better adapted to agroclimatic conditions and market requirements, which have consumption preferences for products with better organoleptic characteristics and healthier properties. Landraces show their maximum potential under agroecological farming systems, where rhizosphere beneficial microorganisms in general and mycorrhizal fungi in particular have a positive interference in their development, especially when plants are subjected to biotic or abiotic stresses. This work has been designed in order to optimize tomato crops with agroecological practices. In order to achieve this, different complementary approaches have been evaluated with one the most active components of rhizospheric microbiota such as arbuscular mycorrhizal fungi. The objective of this research is to improve crop conditions and increase the stress tolerance of landraces with local microorganisms and agroecological practices. Different problematic aspects of cultivation in the archipelago have been studied, such as the low quality of irrigation water, root parasites, soil and microbiological characteristics, etc. Firstly, the physical-chemical and biological soil properties and biodiversity of tomato crops under conventional and ecological management systems were evaluated in Tenerife. The results showed higher organic matter and nitrogen content in the soil of ecological management crops as well as higher mycorrhizal fungi propagules, cultivatable filamentous fungi and yeasts, with a consequent increase in biological activity. Also, the identification of cultivatable microorganisms was carried out and specificity with the type of management system was founded. The mycorrhizal dependence (mycotrophic capacity of plants) of six different variants of "Manzana Negra" landrace (Alajeró, Teguise, San Bartolomé, Yaiza, Lanzarote and Tinajo) were studied, using a native “Glomus mosseae” mycorrhizal fungus and watered with different phosphorus levels. All plant variants showed a good mycorrhizal dependence reflected by an increase in the development of plants. In the Canary Islands, the common problem of abiotic stress in tomato cultivation, caused by low quality irrigation waters, was evaluated using Alajeró plants. The results showed native mycorrhizal fungi improved plant growth and nutrition, when they are affected by salinized irrigation waters with chloride and carbonate sodium. Likewise, the combined use of local mycorrhizal fungus and organic matter against the parasite nematodes of the genus Meloidogyne, present in Canarian tomato crops, was studied. A protection was exerted by micorrizal fungus on plants affected by this parasite. Organic matter improved the crop conditions and showed a significant decrease of nematodes on roots. Finally, the effects of mycorrhizal fungi were evaluated for the production and fruit quality of the Alajeró plants under real agroecological crop conditions. The benefits were verified in the yield, which was characterized by having a greater fruit weight and quantity. This hypothesis has been confirmed by the results and supports the suitability of mycorrhizal fungi use on landrace tomato crops in agroecological conditions in the Canary Islands and also provides a tool that benefits the sustainability of these systems.