Background and Aims:

Conifers, such as pines, establish obligate symbioses with ectomycorrhizal fungi and specialized bacteria in their roots. Mexico has a high diversity of species of the genus Pinus, represented by 72 taxa in this country. However, currently the research related to the coinoculation of Mexican pines with ectomycorrhizal fungi and beneficial bacteria has received little attention. In this work, the effect of coinoculation with an edible ectomycorrhizal fungus and three bacterial strains was evaluated in terms of growth, physiological and nutritional variables in plants of Pinus montezumae.

Methods:

Pinus montezumae plants were inoculated and coinoculated with the edible ectomycorrhizal fungus Laccaria laccata, and with three identified bacterial strains: one as Cohnella sp., and two as Azospirillum brasilense (one able to fix nitrogen and the other one able to solubilize phosphates). This research lasted 520 days and was carried out in a greenhouse of the Colegio de Postgraduados, Campus Montecillo, Texcoco, Mexico State, Mexico.

Key results:

Inoculation with the ectomycorrhizal fungus led to an increase in terms of dry weight of up to 7.8 times and photosynthetic rate up to 30 times higher compared with plants without any inoculation. Additionally, a synergistic effect was recorded in terms of shoot and total growth, stem diameter, photosynthetic rate, total chlorophyll and carotene content, as well as nitrogen and potassium content of the mycorrhized plants coinoculated with the ectomycorrhizal fungus and the bacterium A. brasilense able to fix nitrogen.

Conclusions:

This work demonstrates the importance of the coinoculation of an edible ectomycorrhizal fungus and the bacterium A. brasilense, in terms of growth, physiology and nutritional content enhancement of P. montezumae, a pine species of great forest importance in Mexico.

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