**6. Arbuscular mycorrhizal (AM) fungi**

The symbiotic association between fungus and root systems of higher plants is called mycorrhiza, which literally means root fungus. Ectomycorrhizae and entomycorrhizae or arbuscular mycorrhizae (AM) are playing important role in phosphorus and micronutrients uptake by tree species. The AM fungi association is endotrophic, and has previously been referred to as vesicular-arbuscular mycorrhiza (VAM), this name has been dropped since 1997 in favor of AM fungi, because all fungi are not produced vesicles [46]. Arbuscular mycorrhizal fungi belong to the

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organism applied alone.

*Sustainable Development of Horticulture and Forestry through Bio-Inoculants*

**6.1 A combined effects AM fungi and** *Pseudomonas* **in tree species**

effects on plants on plant growth of AMF and rhizobacteria [61, 62].

The occurrence of AM spores depends upon the environmental conditions, plant species and soil type. There are two different types of AM spores such as *Acaulospora* and *Glomus* were observed in non-rhizosphere soil. Among the two different AM spore, Glomus was the dominant one. Spore density was very low 8 spore/100 g of soil [63, 64]. Analysis of root colonization was higher in mycorrhizal than non- mycorrhizal plants. Santhaguru et al. [65] reported that VAM infection

**6.2 Effect of AM spores in rhizosphere of three species**

The interaction between *Pseudomonas* and the arbuscular mycorrhizal fungus,

The highest mycorrhizal root colonization and number of AM fungal spores, and pseudomonas population were observed when *G. fasciculatum* and *P. monteilii* were coinoculated on to *Coleus forskohlii* plants [56] under organic field condition. Negative effects of *Glomus intraradices* on population of PGPR, *P. fluorescens* DF57 were shown by Ravnskov et al. [57] and suggested that competition for inorganic nutrients might explain the effect, since the mechanism did not require cell-to-cell contact. Marschner et al. [58, 59] suggested that similar negative effects of *Glomus intraradices* on *P. fluorescens* 2-79RL might be due to mycorrhizal induced decreases in root exudation, affecting the composition of the rhizosphere soil solution. *P. fluorescens* 92rk and P190r, and *G. mosseae* BEG12, inoculated alone, promoted tomato plant growth. Plant growth promotion by florescent pseudomonads has been ascribed to the suppression of phytopathogenic soil-borne microorganisms [43, 60]. Moreover, co-inoculation of three microorganisms showed synergistic effects compared with single inoculated plants and reports demonstrate additive

*Glomus clarum* NT4 on spring wheat grown under gnotobiotic condition was investigated [55]. Although plant growth responses varied, positive response to Pseudomonad inoculants was obtained. Shoot biomass enhancement ranged from 16 to 48%, whereas enhancement ranged from 82 to 137% for roots. Typically, dual inoculation positively influenced the magnitude of response associated with any

division Zygomycetes and order Glomales. There are six genera of AM fungi have been identified and are *Glomus, Gigaspora, Aculospora, Scutellospora, Entrophosphora,* and *Sclerocystis. Acaulospora* and *Scutellospora* belong to Gigasporaceae; *Glomus* and *Sclerocystis* belong to Glomaceae [47]. Arbuscular mycorrhizal fungi (AMF), belonging to the phylum *Glomeromycota,* are obligate symbiotic fungi forming mutualistic associations with the roots of most of the tropical plants. Increased access to lowmobility soil mineral nutrients has been considered to be main beneficial effect of AMF on their host plants [48]. In addition, they have been shown to improve the uptake of Zn, Cu, S, Mg, Ca, K and other nutrients [49]. The AM fungal mycelia have been reported to stabilize soil through the formation of soil aggregated [50]. Arbuscular mycorrhizal (AM) fungi are the most widespread type and ecologically important root fungal that form symbiosis with 80% of land plant species which depend upon them for growth [51]. AM fungal symbiosis is characterized by fungal penetration of root cortical cells forming microscopic branched structures called arbuscules that increase that increase efficiency of plant-fungus metabolite exchange [48]. These microsymbionts occur widely under various environmental conditions with beneficial effects on soil structure improvement [52, 53] and have great importance due to their higher capacity to increase growth and yield through efficient nutrient uptake in infertile soils, water uptake and drought resistance in plants [54].

*DOI: http://dx.doi.org/10.5772/intechopen.87148*

#### *Sustainable Development of Horticulture and Forestry through Bio-Inoculants DOI: http://dx.doi.org/10.5772/intechopen.87148*

*Sustainable Crop Production*

**5.3 Pseudomonas**

*Moringa oleifera* [25]*, Acacia nilotica* [26]*, Azadirachta indica* [37]*, Delonix regia* [28]*, Erythrina indica* [29]*, Feronia elephantum* [30]*, Jatropha curcas* [31]. Two years old *Casuarina equisetifolia* plants treated with bio-inoculants in field condition improve the growth of plants by 90% over uninoculated control [32]. *Azospirillum lipoferum* treated with *Jatropha curcas* under field conditions has increased the shoot length by 44.85% and primary and secondary root length by 39.3 and 37.5% respectively. Similarly, the root and shoot biomass also increased by 24.01 and 15.04% leaf area by 28.57% increase over control and the other *Azospirillum* species such as *A. brasilense*, *A. haloference* and *A. amazonense* [33]. The stimulatory effect exerted by *Azospirillum* has been attributed to several mechanisms including secretion of phytohormones (auxins and gibberellins), biological nitrogen fixation, and enhancement of mineral uptake of plants [8] due to the ability of synthesis of in vitro phyto-hormones such as

IAA, gibberellins, cytokinin [34, 35] and produced by ethylene [36].

**5.2 Effect of bio-inoculants and biochemical changes of tree crops**

Plants inoculated with *A. brasilense* were always characterized by a higher chlorophyll concentration. Inoculation of crops caused a statistically significant increase of chlorophyll content in the case of oats in 1996 (15%) and wheat in 1997 (15%). Chlorophyll appeared to be a sensitive indicator of inoculation effect, which was also supported by Bashan et al. [37]. *A. lipoferum* inoculated *Jatropha curcas* seedlings has increase in level of chlorophyll a, b and carotene and such increase was maximum by 31.98, 14.5 and 18.9% and protein content (37.35%) amino acid (26.33), lipids (8.9) and carbohydrates (9.37) when compare to control plant under field conditions [31]. The total chlorophyll and soluble protein content was found to

be higher in the *Moringa oleifera* seedlings inoculated with *A. brasilense* [25].

nutrition [44] and phytohormone synthesis [45].

**6. Arbuscular mycorrhizal (AM) fungi**

The genus *Pseudomonas* is one of the most diverse gram-negative non-spore forming, motile, rod shaped bacteria with an important metabolic versatility and pathogenicity [38]. Morphologically this genus is straight or slightly curved rods and produced yellowish green pigment in King's B. Medium. Plant growth promoting rhizobacteria consisting of primarily *Pseudomonas fluorescens* and *P. putida* were identified as important organisms with ability for plant growth promotion and effective disease management properties. The population density of fluorescent pseudomonas in the rhizosphere in usually reduced by AM fungi colonization [34, 39, 40]. Many strains of genus *Pseudomonas* possess the capability to promote plant growth [41], due to their 1-aminocyclopropane-I carboxylate deaminase activity, indole acetic acid (IAA) and siderophore production [42], PGPR can exert a beneficial effects on plant growth by suppressing soil borne pathogens [43], improving mineral

The symbiotic association between fungus and root systems of higher plants is called mycorrhiza, which literally means root fungus. Ectomycorrhizae and entomycorrhizae or arbuscular mycorrhizae (AM) are playing important role in phosphorus and micronutrients uptake by tree species. The AM fungi association is endotrophic, and has previously been referred to as vesicular-arbuscular mycorrhiza (VAM), this name has been dropped since 1997 in favor of AM fungi, because all fungi are not produced vesicles [46]. Arbuscular mycorrhizal fungi belong to the

**274**

division Zygomycetes and order Glomales. There are six genera of AM fungi have been identified and are *Glomus, Gigaspora, Aculospora, Scutellospora, Entrophosphora,* and *Sclerocystis. Acaulospora* and *Scutellospora* belong to Gigasporaceae; *Glomus* and *Sclerocystis* belong to Glomaceae [47]. Arbuscular mycorrhizal fungi (AMF), belonging to the phylum *Glomeromycota,* are obligate symbiotic fungi forming mutualistic associations with the roots of most of the tropical plants. Increased access to lowmobility soil mineral nutrients has been considered to be main beneficial effect of AMF on their host plants [48]. In addition, they have been shown to improve the uptake of Zn, Cu, S, Mg, Ca, K and other nutrients [49]. The AM fungal mycelia have been reported to stabilize soil through the formation of soil aggregated [50].

Arbuscular mycorrhizal (AM) fungi are the most widespread type and ecologically important root fungal that form symbiosis with 80% of land plant species which depend upon them for growth [51]. AM fungal symbiosis is characterized by fungal penetration of root cortical cells forming microscopic branched structures called arbuscules that increase that increase efficiency of plant-fungus metabolite exchange [48]. These microsymbionts occur widely under various environmental conditions with beneficial effects on soil structure improvement [52, 53] and have great importance due to their higher capacity to increase growth and yield through efficient nutrient uptake in infertile soils, water uptake and drought resistance in plants [54].

#### **6.1 A combined effects AM fungi and** *Pseudomonas* **in tree species**

The interaction between *Pseudomonas* and the arbuscular mycorrhizal fungus, *Glomus clarum* NT4 on spring wheat grown under gnotobiotic condition was investigated [55]. Although plant growth responses varied, positive response to Pseudomonad inoculants was obtained. Shoot biomass enhancement ranged from 16 to 48%, whereas enhancement ranged from 82 to 137% for roots. Typically, dual inoculation positively influenced the magnitude of response associated with any organism applied alone.

The highest mycorrhizal root colonization and number of AM fungal spores, and pseudomonas population were observed when *G. fasciculatum* and *P. monteilii* were coinoculated on to *Coleus forskohlii* plants [56] under organic field condition. Negative effects of *Glomus intraradices* on population of PGPR, *P. fluorescens* DF57 were shown by Ravnskov et al. [57] and suggested that competition for inorganic nutrients might explain the effect, since the mechanism did not require cell-to-cell contact. Marschner et al. [58, 59] suggested that similar negative effects of *Glomus intraradices* on *P. fluorescens* 2-79RL might be due to mycorrhizal induced decreases in root exudation, affecting the composition of the rhizosphere soil solution. *P. fluorescens* 92rk and P190r, and *G. mosseae* BEG12, inoculated alone, promoted tomato plant growth. Plant growth promotion by florescent pseudomonads has been ascribed to the suppression of phytopathogenic soil-borne microorganisms [43, 60]. Moreover, co-inoculation of three microorganisms showed synergistic effects compared with single inoculated plants and reports demonstrate additive effects on plants on plant growth of AMF and rhizobacteria [61, 62].

#### **6.2 Effect of AM spores in rhizosphere of three species**

The occurrence of AM spores depends upon the environmental conditions, plant species and soil type. There are two different types of AM spores such as *Acaulospora* and *Glomus* were observed in non-rhizosphere soil. Among the two different AM spore, Glomus was the dominant one. Spore density was very low 8 spore/100 g of soil [63, 64]. Analysis of root colonization was higher in mycorrhizal than non- mycorrhizal plants. Santhaguru et al. [65] reported that VAM infection

was 100% in *Albizia amara, Peltophorum pterocarpum* and *Pongamia glabra, 80% in Derris scandens* 78% in *Erythrina variegata*, 18% in *Pterlobium* and16% in *Prosopis chilensis*. However, there is no VAM fungi infection in five plant species viz. *Albizia lebbeck, Bauhinia tomentosa, Cassia, Prosopis juliflora* and *Tamarindus indica* at Alagar Hills of Tamil Nadu, India. Similarly, AM Fungi colonized with several tree species semi-arid zone of South India, 1, 2 and 3 years old *Casuarina equisetifolia* [2], *Leucaena leucocephala* [66], *Feronia elephantum* with AM fungi (*Glomus fasciculatum*), *Samanea saman* [67]. Similarly, 16 different species of Arbuscular mycorrhizal fungi were isolated from rhizosphere of teak (*Tectona grandis*) among these *Glomus* and *Aculospora* found in dominant species and seedlings inoculated with combination of Arbuscular fungi had good quality seedlings and increased shoot height compared to with individual AM fungus in *Tectona grandis* [68].

#### **6.3 Role of bio-inoculants on plant growth and metabolites**

*Leucaena leucocephala* seedlings were inoculated with different types of vesiculararbuscular mycorrhizal fungi found that the collar diameter increment of between 18 and 123% [66]. Similarly, *Pterocarpus indicus* inoculated with vesicular-arbuscular mycorrhizal fungi improve the shoot diameter [69], root collar diameter in sweet gum seedlings by 268% [70]. *Feronia elephantum* with AM fungi (*Glomus fasciculatum*) increase the plant growth especially root length and was recorded the root length increment was up to 84% [30]. Similarly shoot length was higher in *Samanea saman* [67] Mycorrhiza colonization also protect the roots from the soil pathogens [71]. AM fungi significantly increase the net photosynthesis by increasing total chlorophyll and carotenoid contents ultimately increasing carbohydrate accumulation. The chlorophyll content, fresh weight and leaf area are higher in mycorrhizal plants than in non-mycorrhizal plants but differences are significant only under draught stress conditions [72]. In mycorrhizal infected groundnut roots, high concentrations of ortho-hydroxy phenols were present. This type of phenols has been known to play an important role in plant disease resistance [73]. Inoculation of AM fungi is enhancing the plant quality by stimulating the synthesis of secondary metabolites which can be important for plant tolerance to abiotic and biotic stresses [74]. According to Morandi et al. [75] the Phenolic substances, such as phytotoxins are synthesized when the root is infected by a pathogen. They are non-specific toxic substances, which can be considered to play a role in disease resistance. Kapoor et al. [76] observed a significant increase in the density of glandular trichomes in the medicinal plant *Artemisia annua* following inoculation with the AM fungi *G. macrocarpum* and *G. fasciculatum* contributing to enhance artemisinin content in the plants.

The chlorophyll a, chlorophyll b, total chlorophyll and Carotenoid contents increased in mycorrhizal seedlings compared with non-mycorrhizal tree seedlings of *Cassia siamea*, *Delonix regia*, *Erythrina variegata*, *Samanea saman* and *Sterculia foetida* [77]. A significant enhancement in biochemical parameters like total chlorophyll content, soluble protein and NRase activity in *Pongamia pinnata* seedling 10.7, 48.5 and 43.6% increase over control with the combined inoculation of Rhizobium, Phosphobacteria and AM fungi [78]. Similarly, an increase in chlorophyll content and soluble protein was observed in *Ziziphus mauritiana* when inoculated with AM fungi [79] and *Dalbergia sissoo* inoculated with Rhizobium and mycorrhizae [80] and in Shola species inoculated with Azospirillum + Phosphobacteria and AM fungi [22]. Eucalyptus seedlings inoculated with mixed *Glomus mosseae, Trichoderma viride* and *Glomus fasciculatum* increases the phosphorous content of shoot and root over control. Then increased rate of P uptake and inflow in roots is regarded as the major contribution of AM infection [81]. The AM colonization increased initially up to 45 days but decreased thereafter [82].

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*Sustainable Development of Horticulture and Forestry through Bio-Inoculants*

The fundamental importance of the mycorrhizal associations in restoration and to improve the revegetation is well recognized [83]. Arbuscular mycorrhiza colonized plants showed significant increment in height, biomass production and girth as compared to non mycorrhizal plats. Growth, biomass and P uptake were higher were higher on dual inoculation of *G. fasciculatum* and *G. macrocarpum* as compared to uninoculated tree species under both nursery and field condition. Tropical trees inoculated with AM fungi have shown increased nutrient uptake and growth, withstanding the transplant stock, hostile conditions like drought resistance and survival of *Acacia holosericea* [84]. *Casuarina equisetifolia* seedlings inoculated with AM (*Glomus fasciculatum*) increased shoot and root biomass [23, 24], *Eucalyptus tereticornis* [85] *Tectona grandis* [68] *Santalum album*, *Acacia auriculiformis*, *Grevillea robusta*, *Eucalyptus camaldulensis*, *Bombax ceiba* [86, 87]

Inoculation with *Glomus mosseae* and *G. fasciculatum* along with other nitrogen fixing and phosphate solubilizing organism improved the quality and growth of neem seedlings, owing to greater absorption of nutrients, under nursery conditions in unsterilized soil [89], AM fungus (*G. fasciculatum*) and Rhizobium treated *Acacia nilotica* seedlings recorded an increase in shoot and root biomass [90]. Beneficial effects of AMF, such as growth promotion, increased root branching, lengths of lateral roots, specific root length and root diameter [91], protection against pathogens [92] and tolerance to abiotic stresses [93], could be due to positive interactions between mycorrhizae and associated microorganisms such as Pseudomonas, Arthrobacter and Burkholderia in a particular environment [94]. Combined inoculation of *Glomus fasciculatum* and Rhizobium on the growth of *Prosopis juliflora* seedlings showed better growth on shoot length and biomass. It was found that *G. fasciculatum,* Scutellospora sp., *G. leptotichum* and *G. mossease* were most efficient for *Dalbergia sissoo*, *Acacia auriculiformis*, *A. nilotica* and *Dalbergia latifolia,* respectively, and increase in plant biomass and height was to the extent of 34 and 24%, respectively, in *Dalbergia sissoo*, 126 and 50% in *A. auriculiformis*, 48 and 24% in *Dalbergia latifolia* and 100 and 112% in *Acacia nilotica* [95].

The genus Trichoderma is the most common fungi found in all climatic condition. It can be isolated in all type of soil. It is also found in plant root, rotting wood, plant litter and seed. Fungi of the genus Trichoderma are important biocontrol agents (BCAs) of several soil borne phytopathogens. Trichoderma use different mechanisms for the control of phytopathogens which include mycoparasitism, competition for space and nutrients, secretion of antibiotics and fungal cell wall degrading enzymes. In addition, *Trichoderma* could have a stimulatory effect on

Shoot length and fresh weight were more in *Eucalyptus saligna* seedlings inoculated with *Trichoderma viride*. The greater height and fresh weight of *Acacia nilotica* inoculated with Trichoderma due to the Trichoderma species produce growth hormones which result in better growth of shoots. *Trichoderma* sp. co-inoculated with *Azotobacter* sp. and *Bacillus megaterium* showed a significant increase on the growth of Teak and Indian red wood under nursery condition [96]. The growth promoting substances are known to cause enhanced cell division and root development [97]. Similarly, many strains of Bacillus pseudomonas and Trichoderma have been

plant growth 48 as a result of modification of soil conditions.

implicated in improvement of overall growth of many crop plants [98].

**6.4 Effect of AM fungi on growth and nutrient content**

*DOI: http://dx.doi.org/10.5772/intechopen.87148*

and *Albizia lebbeck* [88].

**7. Trichoderma**

#### **6.4 Effect of AM fungi on growth and nutrient content**

The fundamental importance of the mycorrhizal associations in restoration and to improve the revegetation is well recognized [83]. Arbuscular mycorrhiza colonized plants showed significant increment in height, biomass production and girth as compared to non mycorrhizal plats. Growth, biomass and P uptake were higher were higher on dual inoculation of *G. fasciculatum* and *G. macrocarpum* as compared to uninoculated tree species under both nursery and field condition. Tropical trees inoculated with AM fungi have shown increased nutrient uptake and growth, withstanding the transplant stock, hostile conditions like drought resistance and survival of *Acacia holosericea* [84]. *Casuarina equisetifolia* seedlings inoculated with AM (*Glomus fasciculatum*) increased shoot and root biomass [23, 24], *Eucalyptus tereticornis* [85] *Tectona grandis* [68] *Santalum album*, *Acacia auriculiformis*, *Grevillea robusta*, *Eucalyptus camaldulensis*, *Bombax ceiba* [86, 87] and *Albizia lebbeck* [88].

Inoculation with *Glomus mosseae* and *G. fasciculatum* along with other nitrogen fixing and phosphate solubilizing organism improved the quality and growth of neem seedlings, owing to greater absorption of nutrients, under nursery conditions in unsterilized soil [89], AM fungus (*G. fasciculatum*) and Rhizobium treated *Acacia nilotica* seedlings recorded an increase in shoot and root biomass [90]. Beneficial effects of AMF, such as growth promotion, increased root branching, lengths of lateral roots, specific root length and root diameter [91], protection against pathogens [92] and tolerance to abiotic stresses [93], could be due to positive interactions between mycorrhizae and associated microorganisms such as Pseudomonas, Arthrobacter and Burkholderia in a particular environment [94].

Combined inoculation of *Glomus fasciculatum* and Rhizobium on the growth of *Prosopis juliflora* seedlings showed better growth on shoot length and biomass. It was found that *G. fasciculatum,* Scutellospora sp., *G. leptotichum* and *G. mossease* were most efficient for *Dalbergia sissoo*, *Acacia auriculiformis*, *A. nilotica* and *Dalbergia latifolia,* respectively, and increase in plant biomass and height was to the extent of 34 and 24%, respectively, in *Dalbergia sissoo*, 126 and 50% in *A. auriculiformis*, 48 and 24% in *Dalbergia latifolia* and 100 and 112% in *Acacia nilotica* [95].
