Effects of Tuber borchii inoculation on Pinus pinea 3 years after establishment along a latitudinal gradient in the Southern Hemisphere

Abstract

Stone pine (Pinus pinea) produces a highly demanded dried fruit, the pine nuts; Tuber borchii produces a well-known commercialized truffle. Thus, the co-culture of P. pinea and T. borchii may represents an interesting productive option. This work evaluated the effect of T. borchii inoculation on stone pine tree growth, survival, health, entry into cone production, and mycorrhization level during the first 3 years after establishment along a 2000 km gradient in Chile. We tested two treatments (inoculation and non-inoculation) in a multi-environment trial (MET) involving seven sites along Chile. Plantations were repeatedly measured during 3 years after establishment. In all environments, inoculation enhanced tree height, root collar diameter (RCD) and crown diameter (6.9, 10 and 8.3% higher for inoculated than for non-inoculated plants). Vigor was also favored (14.1% more vigorous trees). Stone pine performance was enhanced in all sites, but mainly in those with extreme environmental conditions. T. borchii mycorrhizae were abundant (over 60% of mycorrhized root apexes) 3 years after establishment. The truffle-host plant combination was not previously evaluated in Chile. The results showed high root colonization levels and the persistence of mycorrhization 3 years after establishment, and an enhanced effect of mycorrhization on tree growth and vigor under different soil and climate conditions, confirming the high plasticity of both species.