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.
GPR investigations were used to study degraded road pavements built in cutting sections. Road integrity was assessed via quantitative analysis of power curves. 1600 MHz and 600 MHz radar sections were collected in 40 damaged and undamaged road pavement sites. The collected data were processed as follows: (i) linearisation with regression analysis of power curves; (ii) assessment of absorption angleα′ which is directly proportional to absorption coefficientα(this was obtained by setting the e.m. propagation velocity to 10 cm/ns); (iii) comparison of absorption coefficients in both damaged and undamaged zones with respect to road pavement degradation. If the absorption coefficients of damaged and undamaged road sections have nearly the same value, then the likely cause of degradation is the fatigue or the thermal shrinkage; if they are not, then road degradation is due to the different compactness of the soil caused by vehicular traffic load. In a considerable number of sites, the statistical comparison of damaged and undamaged zones through the absorption coefficient analysis shows that surface observations of road pavements are quite consistent with power curve analyses.
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