Results of the analysis of variance are provided in Table 1. In almost all cases salinity and mycorrhiza were significant sources of variation. Interactions between AMF and clone were almost always significant sources of variation, indicating species-specific AMF responses on different eucalyptus clones. Eucalyptus clone and the other interactions were occasionally significant sources of variation as well.
[Insert Table 1 here]
AMF colonization and spore density
Table 2 shows fractional root colonization and spore abundance of AMF at different salinity levels. Control plants were also colonized, as the field inoculation had not been sterilized, however, colonization levels were much lower than in the pre-inoculated seedlings. Colonization declined with increasing salinity levels. Next to mycorrhiza and salinity as significant sources of variation, variety (clone) was also a significant source of variation. Fractional root colonization on H8 was higher than that on H4 and P6. The significant interaction mycorrhiza × variety was due to the fact that Glomus sp.2 reached highest colonization on P6, whereas G. albida achieved highest colonization on H8 and H4. Spore densities were much higher in the pre-inoculated clones that in the clones that did not receive pre-inoculation. Spore densities salinity levels. Variety and the interaction mycorrhiza × variety were also significant sources of variation (Table 1). Like fractional root colonization spore densities with H4 and H8 were highest with G. albida, while spore densities with P6 were highest with Glomus sp.2. Mycorrhizal colonization and spore abundance were very significantly correlated (r = 0.64; n = 36; P < 0.001).
[Insert Table 2 here]
Shoot dry weight was significantly affected by mycorrhiza and salinity. The interaction mycorrhiza × variety was also a significant source of variation (Table 1). Shoot dry weight was negatively influenced by increasing salinity levels, both for pre-inoculated and control plants. The symptoms of salt toxicity were observed, with leaves becoming sapless and showing signs of chlorosis. The damage to plants was more severe in control plants than in pre-inoculated plants at the same salinity level. At all salinity levels, plant pre-inoculated with G. albida usually showed much higher shoot dry weight than plants pre-inoculated with the other AMF or without pre-inoculation. However, at the intermediate salinity levels P6 plants, when pre-inoculated with Glomus sp.2, were significantly heavier than when pre-inoculated with the other AMF or when not pre-inoculated. Under those conditions, plants pre-inoculated with G. albida had lowest shoot dry weight (Table 3). Plant height followed more or less the same pattern as shoot dry weight, with a negative effect of salinity and a positive effect of pre-inoculation by AMF. Plant height of clone H4 was lower than that of the other two clones. Shoot dry weight and plant height were very significantly positively correlated (r = 0.83. n = 36; P < 0.001).
Leaf relative water content was also significantly affected by salinity, mycorrhiza, variety, and the interaction between mycorrhiza × variety and salinity × variety (Table 1). Salinity reduced and mycorrhiza increased LRWC. Again, the combination of clone H8 with G. albida and the combination P6 with Glomus sp.2, resulted in positive interactions. Clone H8 exhibited somewhat lower LRWC than the two other clones (Table 5).
For root dry weight, all three main factors were significant sources as variation. The mycorrhiza × variety interaction was also a significant source of variation (Table 1). Increasing salinity levels reduced root dry weight. Mycorrhizal plants, especially cutting pre-inoculated with G. albida, increased root dry weight. Root dry weight of clone H4 was significantly higher than that of the other two clones, especially at the two higher salinity levels (Table 3). Root dry weight was very significantly correlated with shoot dry weight (r = 0.85, n = 36; P <0.001).
[Insert Table 3 here]
Root length and root surface area were both significantly affected by salinity level, mycorrhiza and the interaction mycorrhiza × variety. In the case of root surface area, the interaction salinity × variety was also a significant source of variation (Table 1). Root length had high significantly positive correlation with leaf relative water content (LRWC) but root diameter had significantly negative with root length, specific root length and root tissue density (Table 4). Salinity reduced, and pre-inoculation with mycorrhiza increased root length and root surface area. Clone H4 and H8 showed the strongest effect in interaction with G. albida, whereas clone P6 showed the strongest interaction with Glomus sp.2 (Table 5)
[Insert Tables 4 & 5 here]
Plant nutrient concentration
AMF, salinity and variety of eucalyptus had significantly with all of nutrients concentration in plant tissue. Especially, the interaction of AMF and salinity had high significantly in concentration of N, Na and K/Na ratio (Table 1). Concentrations of N, P and K in the plant shoots decreased with higher NaCl concentrations, whereas Na increased with higher NaCl concentrations (Table 6). In this study, AMF inoculation was found to enhance nutrient uptake more than the non-AMF plants across all salinity levels. Eucalyptus H4 and H8 strains inoculated with Gi. albida had significantly higher total N, K, and lower Na absorption than the control. In the case of P, the results reveal that H4 and H8 had significantly higher concentrations than the control as a result of the fungus at all salinity levels, with the exception of P at 20 dS m-1. The eucalyptus P6 strain inoculated with Glomus sp.2 showed significantly higher N, P and K, and lower Na absorption than the control (Table 6).
[Insert Table 6 here]
Leaf chlorophyll concentration
Leaf chlorophyll concentration, an important physiological indicator for plant photosynthetic capacity, was significantly affected by all three main factors (salinity, mycorrhiza, variety) and by all two-way and three-way interactions (Table 1). All of chlorophyll had high significant positive correlation but negative correlation with proline concentration (Table7). Mycorrhiza significantly increased leaf chlorophyll concentration, whereas increasing salinity reduced it. In some combinations of variety and AMF species, there was a major effect of increasing salinity levels from 10-15 dS m-1, whereas in other combinations a major decline was observed only when salinity was increased from 15 to 20 dS m-1. Due to the fact that two-way and three-way interactions were significant, other patterns were difficult to explain. Eucalyptus clones H4 and H8 inoculated with G. albida had higher chlorophyll concentration compared to other mycorrhizal treatments, while eucalyptus clone P6 inoculated with Glomus sp.2 had higher leaf chlorophyll concentration (Fig. 1-3) than the other mycorrhizal treatments.
[Insert Table 7 here]
[Insert Figures 1 - 3 here]
Leaf proline concentration
Like chlorophyll, leaf proline concentrations were significantly affected by all main factors (mycorrhiza, salinity, variety) and all two-way and three-way interactions (Table 1). Proline concentrations increased with increasing salinity and were lower for plants that were pre-inoculated than for control plants, At the lowest salinity level there were significant differences between varieties, with H8 showing lowest proline concentration and H4 showing highest concentrations. With increasing salinity levels, the differences between the varieties attenuated. Eucalyptus H4 and H8 inoculated with G. albida and P6 inoculated with Glomus sp.2 had significantly lower proline concentrations across all salinity levels (Fig. 4).
[Insert Figure 4 here]