The effects of water activity (aW, 0.994-0.85 = 0.4-21.0 (-)MPa water potential), temperature (5-42 degrees C), and their interactions on microconidial germination of three isolates each of Fusarium moniliforme and Fusarium proliferatum were determined in vitro on a maize meal extract medium. Temporal germination rates of microconidia of isolates of both species were significantly influenced by both aW and temperature. Germination was very rapid at > 0.94 aW with an almost linear increase with time. Germination rates of microconidia of F. moniliforme were slower than those of F. proliferatum isolates at marginal aW levels and 5-25 degrees C, while at higher temperature (30-37 degrees C), the former germinated more rapidly than the latter. The aW minima for germination of isolates of both species was 0.88, with none occurring at 0.85 aW over a 40-day incubation period. At 37 degrees C, isolates of F. moniliforme had slightly lower aW minima than those of F. proliferatum. The narrowest range of aW for germination was at 5 degrees C, and none occurred at 42 degrees C. The effect of aW x temperature interactions on the lag phases (h) prior to germination and the germination rates (h-1) were estimated using the Gompertz model and the Zwietering equation. This showed that lag phases were shorter at 25-30 degrees C and 0.994-0.98 aW, and were increased to 10-500 h at marginal temperatures (5-10 degrees C) for F. proliferatum and longer for F. moniliforme. At marginal aW levels (0.92-0.90), lag times were increased to > 250 h. Germination rates (h-1) were different for the two species. Microconidia of F. moniliforme germinated optimally at 25-37 degrees C and 0.96-0.98 aW, but this changed to 30 degrees C at 0.90-0.94 aW, while germination of microconidia of F. proliferatum remained optimum at 30 degrees C, regardless of aW. There were statistically significant (P < 0.01) effects of aW, temperature, isolate, and two- and three-way interactions for F. proliferatum, but there were no intraisolate effects for F. moniliforme. The ecological significance of these data for understanding colonization patterns of these important fumonisin-producing fungi are discussed.
Stone pine (Pinus pinea) grows in natural stands within the Mediterranean basin and its nut is highly appreciated for its nutritional profile. Nevertheless, a decline in this species due to biotic and abiotic damages is currently being clearly observed. This situation has led to its development as a nut crop, to try to save its production and obtain regular harvests over the years. Under this agronomic scenario, the aim of this work was to compare the behavior of the stone pine grafted onto two rootstocks, P. pinea (PP) and P. halepensis (PH), by evaluating cone productivity, tree growth response, mast seeding patterns and pine nut composition. The field test was composed of 14 PH and 14 PP, randomly distributed into groups of 4–5 trees/rootstock. Data were from seven productive growing seasons. The results show higher growth and ripe cone production on PP rather than PH, although the productivity (cones/m2 canopy) was similar. Any effect of rootstock was observed on the mast seeding pattern and weight of cones, while the pine nut composition showed differences in the fatty acids content. The global quality of production was similar in PH and PP.
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