Effects of soil chemical properties on arbuscular mycorrhizal fungal (AMF) symbiosis with wild service tree (
Arbuscular mycorrhizal fungi (AMF) play a critical role in the early establishment of land plants (
Some soil characteristics have significant influences on the development of mycorrhizal fungi in roots, such as potassium (K), nitrogen (
Wild service tree (
In this study, we hypothesized that AMF colonization of specific plants can vary significantly between sites with different soil characteristics. A comprehensive study was conducted to determine how AMF colonization of a wild service tree (
The study was conducted in a natural mixed forest of northern Iran consisting of
Five
Soil pH was measured in a soil:deionized water suspension of 1:2.5. Due to their alkaline nature, P content in the soil samples was determined using the method developed by
Soil K was extracted using the neutral ammonium acetate method (
The method of
The five root samples from each site were carefully washed to remove soil and organic particles. Root samples were then cut into pieces of one cm and preserved in FAA buffer (5 ml formalin: 5 ml acetic acid in 90 ml of 70% alcohol). Roots were stained using 0.05% trypan blue in lactophenol (
AMF spores were extracted by wet sieving (sieves of size 500 and 38 µm), and decanting (
Statistical analysis was conducted using the package SPSS® v. 16 for Windows. Data was subjected to one-way analysis of variance followed by Tukey’s test (α = 0.05) to detect differences in variable means among the three sites. Student
Average values of the soil nutrients at the three sites are presented in
The value of total nitrogen in the soil was significantly higher for Tarkin than for the other areas in both seasons (p < 0.01 -
The P showed no significant differences among Kheiroud and Takrin during spring and autumn seasons. On the other hand, significant differences among these two sites and Lalis were observed (p < 0.05). In general, the highest amount of P was observed in the autumn samples from Lalis.
The mean values of exchangeable K for the sites ranged between 312.23 (Kheiroud) and 566.41 (Lalis) in spring, and between 311.73 (Kheiroud) and 532.05 (Lalis) in autumn. This represents 81.4% and 70.7% differences between minimum and maximum values of K in spring and autumn, respectively. No significant differences were found between K values observed in the Kheiroud and Takrin sites compared to Lalis. In addition, no significant differences were evident between spring and autumn for all sites.
Soil pH was a significant factor in the three sites during spring and autumn. The lowest pH in this study was 6.15 at Lalis and the highest was 8.75 at Kheiroud.
Concerning OM, Tarkin had the highest values during spring and autumn. There was a significant difference among values for Tarkin and Lalis in the spring. In autumn however, significant differences (p < 0.05) were observed among Tarkin and Kheiroud (
The average colonization rates for all sites during the spring and autumn seasons are presented in
Concerning AMF spore numbers, results showed that there was no significant difference in SD among sites during the spring and autumn seasons (
As shown in
The degree of variation observed indicates that the studied parameters were not equally variable among the sites (
The Pearson’s correlation coefficients between soil chemical properties, SD and root length colonization are presented in
There was a significant and positive relationship between K and P in autumn (r =0.670;
There was a non-significant decrease in pH values from Kheiroud to Lalis (
A negative correlation with moderate magnitude was observed between pH and soil P in spring (r=0.571,
There was a significant negative correlation between SD and CaCO3 in spring and autumn (
No significant correlations between SD and other soil parameters between spring and autumn seasons were detected except for CaCO3. As shown in
The correlation coefficient between soil alkaline phosphatase and pH was positive and significant in the spring with
The significant effect of AMF on plant growth and leaf mineral concentrations has been previously documented (
Forest plantation management could greatly benefit from the use of wild service tree with high levels of root colonization by AMF, in particular in arid environments (
Usually, spore density of AMF can be related to root colonization (
According to
There was a significant difference in total nitrogen among Tarkin and the other two sites for both seasons. In addition, the results indicated that the organic matter, the most important nitrogen source (
Factors such as temperature, moisture content (
Several authors have reported that soil K content is influenced by elevation, total nitrogen, and organic matter (
It is reported that AMF colonization could result in higher acid and alkaline phosphatase activities, leading to higher P, N and K content in plant leaves (
Wild service tree is a rare species in the northern forest of Iran. This species is important due to its economic and ecological value. Our results revealed that different soil chemical properties did not have significant effect on root colonization and spore density in the studied sites. Despite the strong differences in site conditions, our results revealed that up to 68% of roots of wild service trees could be colonized by AMF. Since this species is tolerant to direct sunlight and short-time water deficits, the use of wild service trees colonized by AMF could help in afforestation plans, particularly in arid areas.
We would like to thank the staff of Iranian forest, range and watershed organization. This study was partly supported by University of Tehran.
Basic information of the study sites.
Site | Aspect | Elevation(m a.s.l.) | LatitudeN | LongitudeE | Slope(%) | Rainfall(mm) | SoilTexture | Temperature (°C) | ||
---|---|---|---|---|---|---|---|---|---|---|
Min | Max | Mean | ||||||||
Kheiroud | S | 1000 | 36° 40′ | 51° 43′ | 30-70 | 1457 | clay | 7 | 25 | 16 |
Lalis | N-NW | 1700 | 36° 32′ | 51° 23′ | 0-60 | 731 | clay | -10 | 29 | 10 |
Tarkin | N | 1500 | 36° 28′ | 51° 51′ | 30-80 | 1085 | clay-silt | -13 | 32 | 10 |
Mean soil parameters in different seasons at the three study sites. (TN): total nitrogen; (P): phosphorous; (K): potassium; (OM): organic matter; (RC): root colonization; (SD): spore density; (A.P): acid phosphatase; (Al.P): alkaline phosphatase. (*): μg p-nitrophenol g-1 h-1. Means within columns (in separate sites) followed by the same letters were not significantly different (p>0.05) after Tukey’s test.
Site | Season | TN (%) | P(ppm) | K(ppm) | pH | OM(%) | RC(%) | SD(N/g) | A.P* | ALP* |
---|---|---|---|---|---|---|---|---|---|---|
Kheiroud | Spring | 0.25a | 7.16a | 312.23a | 7.99a | 8.29ab | 59.0a | 69a | 499.51a | 627.76ab |
Autumn | 0.22a | 8.64a | 311.70a | 7.93a | 8.13a | 38.5a | 81a | 554.96a | 608.24a | |
Tarkin | Spring | 0.44b | 10.02ab | 315.60a | 7.69a | 12.72a | 60.0a | 56a | 825.06a | 837.77b |
Autumn | 0.43b | 9.46a | 342.10a | 7.62a | 14.15b | 42.0a | 79a | 891.62a | 843.00a | |
Lalis | Spring | 0.18a | 12.22b | 566.40a | 7.32a | 6.64b | 61.0a | 50a | 597.95a | 408.94a |
Autumn | 0.28a | 14.66b | 532.10a | 7.05a | 9.52ab | 44.5a | 77a | 872.85a | 563.00a |
Correlation coefficients between soil parameters in autumn. (TN): total nitrogen; (P): phosphorous; (K): potassium; (OM): organic matter; (SD): spore density; (A.P): acid phosphatase; (Al.P): alkaline phosphatase; (Elev): elevation; (*): p<0.05. (**): p<0.01.
Parameter | P | OM% | pH | TN% | K | CaCO3 | A.P | Al.P | SD | Elev | Slope% |
---|---|---|---|---|---|---|---|---|---|---|---|
P | 1 | - | - | - | - | - | - | - | - | - | - |
OM% | .161 | 1 | - | - | - | - | - | - | - | - | - |
pH | -.080 | -.032 | 1 | - | - | - | - | - | - | - | - |
TN% | .179 | .844** | .090 | 1 | - | - | - | - | - | - | - |
K | .670** | .089 | -.050 | .168 | 1 | - | - | - | - | - | - |
CaCO3 | -.362 | -.422 | .470 | -.424 | -.367 | 1 | - | - | - | - | - |
A.P | .457 | .739** | -.514* | .603* | .384 | -.553* | 1 | - | - | - | - |
Al.P | .104 | .730** | .549* | .741** | -.035 | .077 | .233 | 1 | - | - | - |
SD | -.030 | .091 | -.434 | .030 | .048 | -.577* | .181 | -.368 | 1 | - | - |
Elev | .594* | .312 | -.416 | .280 | .487 | -.537* | .574* | .055 | .420 | 1 | - |
Slope% | -.340 | .376 | -.113 | .447 | -.249 | -.501 | .162 | .068 | .752** | -.018 | 1 |
Acid and alkaline phosphatase differences between seasons. Values are means ± SE. Means were not significantly different between spring and autumn (p > 0.05) after Student’s
Season | Acid phosphatase(A.P) | Alkaline phosphatase(Al.P) |
---|---|---|
Spring | 640.83 ± 56.90 | 624.82 ± 61.45 |
Autumn | 773.14 ± 68.01 | 671.41 ± 54.37 |
Correlation coefficients between root colonization and soil parameters in spring and autumn. (TN): total nitrogen; (P): phosphorous; (K): potassium; (OM): organic matter; (SD): spore density; (A.P): acid phosphatase; (Al.P): alkaline phosphatase; (Elev): elevation.
Root colonization | pH | P | OM% | TN% | CaCO3 | K | A.P | Al.P | SD | Elev | Slope% |
---|---|---|---|---|---|---|---|---|---|---|---|
Spring | -.425 | .201 | -.114 | -.126 | -.207 | .155 | -.025 | -.240 | -.090 | .158 | -.015 |
Autumn | -.146 | .216 | .091 | .025 | -.326 | -.145 | .011 | -.006 | .043 | .402 | .090 |
Correlation coefficients between soil parameters in spring. (TN): total nitrogen; (P): phosphorous; (K): potassium; (OM): organic matter; (SD): spore density; (A.P): acid phosphatase; (Al.P): alkaline phosphatase; (Elev): elevation; (*): p<0.05; (**): p<0.01.
Parameter | pH | P | OM% | TN% | K | CaCO3 | A.P | Al.P | SD | Elev | Slope% |
---|---|---|---|---|---|---|---|---|---|---|---|
pH | 1 | - | - | - | - | - | - | - | - | - | - |
P | -.571* | 1 | - | - | - | - | - | - | - | - | - |
OM% | .320 | .008 | 1 | - | - | - | - | - | - | - | - |
TN% | .254 | -.009 | .977** | 1 | - | - | - | - | - | - | - |
K | -.345 | .506 | .036 | -.284 | 1 | - | - | - | - | - | - |
CaCO3 | .484 | -.462 | -.298 | -.297 | -.352 | 1 | - | - | - | - | - |
A.P | -.103 | .165 | .776** | .747** | .523 | -.496 | 1 | - | - | - | - |
Al.P | .563* | -.220 | .884** | .882** | -.240 | .091 | .612* | 1 | - | - | - |
SD | -.152 | -.060 | .210 | .235 | .130 | -.515* | .172 | -.040 | 1 | - | - |
Elv | -.498 | .628* | -.016 | -.032 | .481 | -.511 | .314 | -.220 | .230 | 1 | - |
Slope% | -.052 | -.113 | .450 | .560* | -.253 | -.513 | .291 | .272 | .814** | -.018 | 1 |