Instrumental monitoring of the birth and development of truffles in a Tuber melanosporum orchard

Abstract

Mycorrhizal symbiotic plants, soil suitability, temperature, and humidity are, by general consensus, considered decisive factors in truffle production. However, experimental approaches to define the environmental conditions that stimulate formation of truffle primordia and promote their growth to maturity have been lacking. By analysis of data of many atmospheric and soil parameters collected since 2009 within a Tuber melanosporum orchard, the trends of metabolic activity, detected as CO2 production in the soil, have been identified as the most reliable parameter to indicate the 'birth' of the truffle primordia. They seem to be produced when mycelial activity is intense and undergoes water stress, after which it resumes. About 6-18 days after recovery of metabolic activity, we could collect primordia of T. melanosporum. Many die or develop too early and consequently rot or are eaten by insect larvae. These events occur several times during summer and autumn, those that 'sprout' in late summer or later grow steadily and reach maturity. Using a particular ground-penetrating radar (GPR) setup to discriminate truffles, we could identify individual truffles in the soil after they have enlarged to at least 6 mm in diameter and follow their growth in volume and diameter over time. These two instrumental methods (CO2 sensor and GPR), although yet to be improved, open new important perspectives to better understand truffle biology and manage truffle orchards to support the newly acquired demonstration of the fundamental role of host plants for the nutrient transfer to the ectomycorrhiza-mycelium-fruiting body complex of T. melanosporum.

Edaphic and temporal patterns of Tuber melanosporum fruitbody traits and effect of localised peat-based amendment

“…The number of FBs per dig varied over the fruiting season. If, as hypothesised by Pacioni et al (2014) 6 , the optimal time for fruiting initiation is characterised by a temperature-moisture window of opportunity, our results could be related to the trends in soil conditions during spring, when fruiting initiation is typically triggered. However, our results could also be explained by time-dependent changes in FB mortality.…”

“…Nest installation creates an abrupt discontinuity in the bulk soil/substrate interface. Pacioni et al (2014) 6 hypothesised that fruiting initiation is triggered by a change in soil environment, which has already been found for other fungi 9 . In our study, the different magnitude of the nest effect on each soil supports this hypothesis.…”

The crop of desert truffle depends on agroclimatic parameters during two key annual periods

“…g Vapour pressure deficit. h Mean temperature autumn (Pacioni et al 2014;Bordallo 2007). Moreover, the correlation with soil water potential, the longest correlation between the crop and any other agroclimatic parameters (Fig.…”

Black truffle cultivation: a global reality

“…But it is also essential to know which factors of the soil environment are involved: Pacioni et al (2014) suggested that variations in soil temperature and water content in spring are key, and proposed to use ground penetrating radars to monitor the sporocarps without disturbing their environment.…”