Mycorrhizal dependency of some foresty tree species saplings.
Arbuscular mycorrhizal (AM) association is the most common symbiotic association of plants with microbes. AM fungi occur in the majority of natural habitats and they provide a range of important biological services, in particular by improving plant nutrition, abiotic resistance, and soil structure and fertility. AM fungi also interact with most crop varieties and forest plants. The possible benefit of AM fungi in forestry can be achieved through a combination of inoculum methods. The mycorrhizal inoculum levels in the soil and their colonization in different forest plant roots which leads to reduce the fertilizers, pathogen effects and fungicides and to protect topsoil, soil erosion, and water-logging. Currently, several reports were suggested that AM symbiosis can improve the potential for different plant species. Two steps could be used to produce high yielding of different plant biomass that would be both mycorrhizal dependency and suitability for sowing into the field with high inoculum levels Therefore, the wide-scale inoculation of AM fungi on forest trees will become economically important. The successful research is required in the area of mass production of AM fungal inoculum and AM fungi associated with roots which will contribute to sustainable forestry.
- sustainable forestry
- mycorrhizal dependency
Arbuscular mycorrhizal fungi are ubiquitous soil microorganisms. AM fungi have great potential to increase plant growth and soil aggregate formation which improves soil quality and development of plant health  AM fungi and microorganisms in the rhizosphere contaminate roots and fabricate rich nutrients condition for plant development . The advantage of AM growths in the field conditions with singular organisms is commonly identified with the rate and degree of mycorrhiza arrangement . Management of AM fungi is required in forestry for high yielding and biomass production to be derived from economic and environmental conditions. Determining the magnitude of benefits from improved AM fungi management the three important factors are required. 1. Mycorrhizal dependency 2. Nutrient status of soil 3. Potential of AM fungal inoculum. The terrestrial plant roots develop AM fungi with natural resources of 80–90% symbiosis . Global occurrence in forest ecosystems and form 50% of microbial biomass in the tropical ecosystem . Among different important functions of the plant-fungal symbiosis, plant growth promotion activity is stimulated by the phosphorus uptake . AMF increase nutrient uptake for the plants, particularly immobile nutrients such as phosphorus (P), copper (Cu), and zinc (Zn) in the soil which are not accessible to plant roots in normal condition due to slow immobility . Moreover, AM fungi support tolerance to the plants from different environmental stresses such as salinity, drought, heat, and pollutants in the rhizosphere soil [8, 9]. Presently, effective management of AM fungi is possible by agronomic practices.
Mycorrhizal dependency (MD) is the most important in developing the management of crop plants and forest trees. Forest plant species derive profit from AM fungi to facilitate equally, another crop species is highly dependent on AM fungi for nutrition, biomass, and growth . The most agricultural plants and forest tree species are hosts of AMF, not all benefit equally. The RFMD (relative field mycorrhizal dependency) proposed by Plenchette et al.  expresses the difference in dry biomass between mycorrhizal and non-mycorrhizal treatments as a percentage of the biomass of mycorrhizal treatment. This method is very useful in the ranking of different host plants with an individual experiment but absolutely the values of RFMD will depend on the nutrient status of the soil. Abbot and Robson  have suggested the need to assess the importance of AM to a host across a full range of soil P levels by determining the response curves for mycorrhizal and non-mycorrhizal plants.
In some forest soils, the response of some crop species to AM fungi is expressed as N as well as phosphate benefits . AM inoculation did not significantly increase shoot dry matter of rice, but it produced significantly higher in biomass than the non-mycorrhizal ones.
A perusal of the Table 1 reveals that all the 10 tree saplings have shown mycorrhizal infection. However, the percent of colonization varied with the tree species. Maximum colonization was observed in
|S. No.||Plant species||% of colonization||P content (%)||Mycorrhizal Dependency|
2. Distribution of AM fungi in forestry
Forests play a progressively more crucial role in gathering the demand for timber and ecological protection, nearly 25% (one fourth) of India’s total land area is now under forest land and tree cover. The diminishing soil quality is the main warning to sustainable forest management, mostly in planted forests. Microorganisms show significant functions in soil formation, aggregation nutrient cycling, nutrient uptake, and reclamation of ecosystems . The arbuscular mycorrhizal fungi (AMF) form symbiotic associations by the plant roots of more than 80% of plants , and they play a crucial role in the successful organization and maintenance of plant communities . AMF hyphae can add phosphorous (P), which cannot be absorbed by root hairs, and the AMF soil mycelial arrangement provides many profits to host plants  as well as plant growth promotion [19, 20] and development of plant resistance to abiotic stress and disease . Additionally, AM fungi can be favorable to soil aggregation as the outcome of the activities of hyphae and glomalin protein secretion  therefore, the incidence and colonization of AM fungi would be helpful to the survival of forest seedlings and the sustainable managing of forests. Furthermore, the AM fungal species associated with plant species have elucidated different functions to host plants and influences on the distribution, diversity, and restoration of plant community . The diversity of AM fungi is significantly important to forest ecosystems and can be important for plant community and productivity [24, 25]. Though, information about the diversity of AMF associated with tree species in forest plants is inadequate. It is a known fact the AM fungi are extensive in different ecosystems, and their colonization and spore propagules are also affected by soil physicochemical characteristics . The abiotic factors could influence on root colonization and fungal spore population.
The AM fungi colonization and spore commune compositions in the rhizosphere of the tree species were estimated. The outcome of this study would provide close on the utilization and supervision of AM fungi to keep sustainable management of forests .
2.1 Forest soils
Table 2 reveals that AM fungal spore population was found highest in Kothagudem soil of
|Location||Plant species||Cumulative spore number||Individual spore incidence|
|Kothagudem||155.0 ± 1.53||98||21||32||4||—|
|92.7 ± 1.45||63||12||11||6||—|
|Bhupalpally||106.7 ± 1.20||76||12||9||6||3|
|137.0 ± 1.73||72||35||16||9||5|
|Godavarikhani||82.3 ± 0.88||48||16||12||—||6|
|63.7 ± 1.45||39||13||8||3||—|
|Yellandu||98.2 ± 0.33||57||23||18||—||—|
|118.7 ± 1.45||80||15||10||7||6|
2.2 Coal mine soils
Table 3 results showed that AM spore number in rhizosphere soil was studied in different Coal mine sites of North Telangana. The results are depicted that AM spore population was observed in two different plant species. AMF root colonization is presented in Figure 2, highest root colonization was recorded in the Kothagudem sample of
|Location||Plant species||Cumulative spore number||Individual spore incidence|
|Kothagudem OCS||79.7 ± 1.45||31||26||11||8||3|
|61.3 ± 1.76||26||15||9||6||4|
|55.7 ± 2.33||33||11||4||5||2|
|63.3 ± 0.88||29||12||10||9||3|
|73.0 ± 1.73||44||14||10||5||—|
|48.7 ± 1.20||17||15||6||6||4|
|53.7 ± 1.45||29||10||7||5||2|
|44.3 ± 0.88||15||13||10||4||2|
|S. No||Treatments||Root colonization|
|Fresh wt.||Dry wt.||Shoot||Root|
Some AM fungi react diversely to soil disturbances, for instance, Hart and Reader  identified that species from the suborder Glomineae were substantially less tough to soil disturbances than species from the suborder Gigasporineae, likely because of the qualities of either colonizing plant roots generally by hyphae or by spores.
Figure 2 shows the highest root colonization in the rhizosphere of
3. AM fungal inoculum development
AMF resting spores collected by stereo binocular microscope were surface sterilized with 200 ppm streptomycin for 15 min and washed in sterile distilled water for several times. The starter culture was prepared by soil funnel techniques . A glass funnel was filled (3/4th) with autoclaved soil and sand (1:1) and the neck was loosely plugged with cotton wool. The funnel was kept over a conical flask (filled with sterile water). Spores were spread near the neck and covered with a thin layer of soil. Seeds of
When an adequate amount of growth was obtained by frequent sowing of seeds, this inoculum was transferred into small plastic pots filled with sand and soil (2:1) and mixed uniformly. Pots were transferred to the greenhouse and seeds of
4. Screening of AM fungal species for efficiency
The effect of native AM fungi on the mycorrhizal intensity in terms of root colonization and spore number in rhizospheric soil of
Biomass of treated plants in the form of fresh weight recorded in
In this study, all the five treatments gave the best results when compared with control (non inoculated tree species)
Among all the five monoculture treatments
5. NPK fertilizers
The use of NPK fertilizers to enhance crop plant production include fertilization is specified to the soil and liquid forms of NPK that are sprayed on top of crop plants. In this time, plants are mostly fulfilled by giving solid fertilizers containing macronutrients, especially N inorganic continuously and without pains to restore the nutrients and absorb the essential elements with plants and causing the decrease of soil fertility [32, 33]. The use of extreme fertilizer is a waste of money and disturbs the stability of nutrients in the soil and increases environmental pollution [34, 35]. To improve the crop productivity and quality of outcome is required to be useful by reasonable fertilizer influences as a result that the proportion of nutrient absorption by plants is balanced and use of one type of fertilizer based on site-specific suggested doses . The site-specific nutrient considers the potential of soils to give usual nutrients recovery . To develop the nutrient status in the soil which administers the N-inorganic fertilizers in the required amounts of P, and K fertilizers are essential to increase crop production.
The compound fertilizers are containing the mineral elements, which need for the successful growth and development of plants. Mineral elements are necessary for optimal doses. Nitrogen, phosphorus, and potassium have enormous effects on plant growth and development. The deficiencies results indicate clear effects on the growth and yield of the crop plants. Nitrogen is a chlorophyll element, which promotes green color and vegetative growth of plants . In agricultural systems, the most important crop nutrients are nitrogen (N), phosphorus (P), and potassium (K) .
Nitrogen fertilizing doses increase the protein levels and crop plant biomass, but the completion of N elements only without P and K will cause plants to simply drop, very sensitive to pest attacks disease, and reduced the quality of crop production . Phosphorus nutrients in the soil absorbed by plants will be supported by P elements specified during fertilization . Nutrient uptake of N, P, and K plants increases with an increasing dosage level of K fertilizer. Potassium is an important component involved in maintaining plant water conditions; it is responsible for regulating stomata opening and closing activities . The multiple inorganic fertilizers added to plants can be either solid form or liquid. The spray of liquid fertilizer to the plants can play a role in improving the properties of the soil and supporting to enhance crop production [41, 42]. The application of liquid inorganic fertilizers is to make it an easy and efficient use of fertilizers by crop plants.
6. Effect of agrochemicals on interactions of Rhizobium and AM fungi on the growth of two forest trees
Different combination of agrochemicals (Captan, Sevin, TCP, Urea, 2, 4-D, DAP) along with Rhizobium and AM fungi were inoculated to test plants combinations are as follows Captan +
AM fungal infection was maximum in plants receiving treatment of E followed by D and F in descending order, while it was low in plants receiving treatment of A and B (Table 5). The spore population also increased in the presence of C, D, and F. Treatments C and D, promoted the plant growth. However, E promoted the maximum height followed by F and D plants, while it was least in B treated plants. Similarly, the treatment of E stimulated nodulation and biomass production. On the other hand, F and D influenced nodulation to an intermediate degree. The addition of tricalcium phosphate adversely affected growth-promoting activity. The degree of nodulation decreased in the presence of captan and sevin which may also partly be due to the absence of
|Trestments||Infection(%)||No. of spores/ 100 g soil||Plant height (cm)||No. of nodules/plant||Biomass||Phosphorus content (mg/plant)|
|Fresh wt.||Dry wt.||Shoot||Root|
|Captan + G.f (A)||47.8 ± 1.28||83.0 ± 0.82||53.0 ± 0.82||—||22.5 ± 0.22||15.4 ± 0.16||0.15 ± 0.01||0.17 ± 0.01|
|Sevin+Gf.(B)||49.0 ± 0.54||104.0 ± 1.63||37.3 ± 1.25||—||20.8 ± 0.29||17.5 ± 0.25||0.28 ± 0.01||0.34 ± 0.02|
|TCP + G.f.(C)||42.5 ± 0.21||114.0 ± 0.82||54.3 ± 1.25||—||35.1 ± 0.53||26.3 ± 0.34||0.22 ± 0.01||0.35 ± 0.02|
|Urea + G.f. + Rhizobium sp.(D)||56.5 ± 1.25||118.0 ± 0.82||62.0 ± 1.63||46.0 ± 1.63||28.0 ± 1.30||18.7 ± 0.17||0.24 ± 0.01||0.34 ± 0.02|
|2,4-D+ G.f. + Rhizobium sp.(E)||58.5 ± 0.22||127.3 ± 1.70||66.0 ± 1.63||56.0 ± 1.63||38.3 ± 0.39||26.6 ± 0.42||0.36 ± 0.02||0.23 ± 0.02|
|DAP+G.f. + Rhizobium sp.(F)||56.4 ± 0.15||112.0 ± 1.63||64.0 ± 1.63||55.3 ± 2.49||37.3 ± 0.70||29.1 ± 0.29||0.14 ± 0.02||0.28 ± 0.01|
|Control+ SS + Rhizobium sp.(G)||46.5 ± 1.25||104.0 ± 1.63||48.0 ± 0.82||—||27.2 ± 0.82||16.4 ± 0.25||0.44 ± 0.22||0.47 ± 0.01|
|Captan + G.f (A)||55.2 ± 0.78||129.0 ± 0.82||52.9 ± 0.29||—||7.06 ± 0.01||3.92 ± 0.02||0.12 ± 0.01||0.15 ± 0.01|
|Sevin+Gf.(B)||64.5 ± 0.50||183.6 ± 2.05||64.4 ± 0.17||—||7.45 ± 0.02||4.14 ± 0.03||0.17 ± 0.01||0.14 ± 0.02|
|TCP + G.f.(C)||61.2 ± 0.49||165.6 ± 2.05||67.4 ± 0.87||—||8.75 ± 0.02||4.56 ± 0.01||0.21 ± 0.01||0.16 ± 0.02|
|Urea + G.f. + Rhizobium sp.(D)||68.1 ± 0.37||212.3 ± 1.70||67.6 ± 0.59||34.0 ± 1.63||9.16 ± 0.02||5.06 ± 0.01||0.22 ± 0.01||0.14 ± 0.01|
|2,4-D+ G.f. + Rhizobium sp.(E)||57.8 ± 1.25||154.3 ± 1.25||63.0 ± 0.62||37.6 ± 1.25||8.05 ± 0.03||6.26 ± 0.01||0.17 ± 0.01||0.13 ± 0.01|
|DAP+G.f. + Rhizobium sp.(F)||54.5 ± 0.68||122.6 ± 1.25||48.3 ± 1.03||27.6 ± 1.25||6.94 ± 0.01||3.72 ± 0.02||0.13 ± 0.01||0.91 ± 0.01|
|Control+ SS + Rhizobium sp.(G)||33.0 ± 0.62||109 ± 0.82||42.7 ± 0.37||—||5.42 ± 0.02||3.03 ± 0.02||0.91 ± 0.01||0.61 ± 0.01|
The biomass production varied with the agrochemicals tried. The maximum AMF root colonization and biomass production was observed in the treatment E, while it was low in sevin treated plants. Similarly, Maximum plant height was recorded with fertilizers, while it was low in F treated plants. Nodulation increased in plants treated with E along with Rhizobium, while it was low in D and F. Treatments of A, B and C were responsible for inhibition of nodulation. On the other hand, the increased biomass production was recorded in plants treated with D and least in F. [43, 44] have recorded the adverse effect of some agrochemicals on AM colonization and growth and development of plants studied by them. Marginal change in physico-chemical characteristics of soils with the addition of different agrochemicals. The pH of the soils ranged between 7.0 and 8.1, and in C, E, and B soil was comparatively more alkaline. Maximum EC was recorded in D plants, while it was least in C plants. Organic matter was maximum in E plants, while it was low in B treated plants. Available phosphorus was also considerably increased in soils receiving different agrochemicals. Maximum available phosphorus was recorded in E treated soils followed by F and D treated plants. Available potassium was maximum in
The root-based hyphal network in soils is the primary inoculum for seedlings that become established on natural grasslands. However, the inoculants colonized roots have some profound disadvantages since they may contain more than one mycorrhizal fungus and may also contain pathogenic organisms. Spores are possibly the best inoculants for laboratory experiments because the features diagnostic of individual species are present only in the spores developed primarily on extra metrical hyphae. Natural soil of crops and forests may contain varying numbers of spores of different AM fungal species. The dual culture using sterile soil with some kind of quality control is believed a practical approach to produce a high level of inoculants for commercial applications. A pot culture of
7. Applications of AM fungi
Arbuscular mycorrhizae show up as an exceptionally encouraging and monetarily reasonable device for the foundation of practical models of rural creation, because of their ability to expand the assimilation of fundamental supplements to plant development and increment their resistance to unfavorable ecological conditions, consequently keeping up soil quality and its gainful potential. Although enhancements in soil quality and plant nutritional status, for mycorrhizae application, was less investigated . Various investigations have indicated that AM Fungi can expand plant health and yield [47, 48]. These symbionts offer an eco-accommodating natural sound substitute to compound composts and pesticides for managing both plant quality and quantity in farming, cultivation, and ranger service. AM Fungi is currently viewed as the base of sustainable farming; so, there is a need to speed up its management in rural establishment frameworks .
The development of AM fungal hyphae is promoted by root exudates and is dependent on the arrangement of an appressorium increases the chance of hyphal entrance in the root framework. Dry weight and mycorrhizal dependence are the two most commonly utilized methods for assess AM fungal impact on plants . Fungal impacts on plant physiology, for example, mineral nutrition especially phosphorus, plant execution, and plant assurance are significant segments in surveying contagious productivity.
AM fungi may similarly have connections among plant development advancing rhizosphere (PGPR) life forms. The impact of AM immunization may shift since numerous elements can impact the event of AM fungi .
The plant root infection and spore population were good in the forest soils and they were less in the overburden coal mine spoils. AMF exhibit different distribution patterns between these two soil types, where
AM fungi and Plant Growth Promoting Rhizobacteria (PGPR) are significant parts in forest development and helps to increase biomass production . There is a need of long term field studies to screen the efficent AM fungi in the revegetation sites and synergistic effects on indigenous microflora on tree growth.