**4.1 Impact of PGPF on seed germination and seedling vigor**

Seed germination and germinant growth are critical developmental periods of the young plantlet until it begins producing its own food by photosynthesis. Treatment with PGPF, particularly of the genus *Aspergillus*, *Alternaria*, *Trichoderma*, *Penicillium, Fusarium, Sphaerodes* and *Phoma* has been reported to improve seed germination and seedling vigor in different agronomic and horticultural crops (**Table 2**). Scarified seeds inoculated with spores from *Aspergillus* and *Alternaria* had significant increases in germination of Utah milkvetch (*Astragalus utahensis*) *in vitro*, and in greenhouse and fall-seeded plots near Fountain Green and Nephi [55]. The *Aspergillus*-treated seeds performed out seeds inoculated with *Alternaria*. An increase of 30% in seedling emergence was observed in cucumber plant raised upon the treatment of *T. harzianum* [47]. Application of *T. harzianum* also significantly increased seed germination, emergence index, seedling vigor and successful transplantation percentage in muskmelon compared to the untreated controls [59]. Early seedling emergence and enhanced vigor were observed in bacterial wilt susceptible tomato cultivar treated with *T. harzianum*, *Phoma multirostrata*, and *Penicillium chrysogenum* compared to untreated controls [34]. The culture filtrate of *Penicillium* was as effective as the living inocula in improving seed germination of tomato [70]. Significantly, higher germination and vigor index were observed in Indian spinach, when seeds were sown in sterilized field soil amended with wheat grain inoculum of *Fusarium* spp. PPF1 [27]. *Sphaerodes mycoparasitica*, a biotrophic mycoparasite of *Fusarium* species, improved wheat seed germination and seedling growth *in vitro* compared to *T. harzianum,* while under phytotron conditions, both *S. mycoparasitica* and *T. harzianum* had positive impact on wheat seedlings growth in the presence of *F. graminearum* [12]. These results show the positive impact of PGPF on seed germination and seedlings growth of a wide arrays of hosts.

### **4.2 Impact of PGPF on shoot growth**

The most common form of growth promotion by PGPF is the augmented shoot in colonized plants. Shoot growth promotion has been shown by a great diversity of PGPF across a large number of plant species. Isolates of *Aspergillus, Trichoderma, Penicillium*, and *Fusarium* were capable of enhancing the shoot growth in model plant Arabidopsis [9, 20, 28, 33, 48]. Different species of *Aspergillus* are known to support shoot growth in chickpea [16], Chinese cabbage [56], cucumber [17], soybean [18, 65] and wheat [76]. Species of nonpathogenic *Fusarium* were reported to stimulate shoot growth in Indian spinach [27] and banana [29]. Application of barley grain inoculum of *Penicillium viridicatum* GP15-1 to the potting medium resulted in 26–42% increase in stem length, 37–46% increase in shoot fresh weight and 100–176% increase in shoot dry weight of cucumber plants [35]. Similarly, inoculation of cucumber plants with *Pe. menonorum* KNU3 increased cucumber shoot dry biomass by as much as 52% [36]. Stimulated shoot growth by *Penicillium* spp. was also reported in tomato [69], Waito-c rice [37, 38], chili [23, 39] and sesame [74]. Application of *T. longipile* and *T. tomentosum* increased shoot dry weight of cabbage seedlings by 91–102% in glasshouse trials [57]. Likewise, cottonseeds pretreated with *T. viride* showed four-fold increases in shoot length elongation and an almost 40-fold increase in plant dry weight compared to the control [66]. Augmented shoot growth by *Trichoderma* has also been reported in chickpea [16], wheat [79], maize [78], cucumber [60] and other plant species (**Table 2**). Isolates of *Phoma* were found to be an efficient stimulator of plant shoot [15, 41, 62]. A few hypovirulent *Rhizoctonia* isolates were able to induce significantly higher fresh leaves and stems weights in tomato plants grown in greenhouse [13]. Enhancement of shoot growth was also observed

**71**

*Application and Mechanisms of Plant Growth Promoting Fungi (PGPF) for Phytostimulation*

*Trichoderma virens* Gv. *29-8* Biomass, lateral root

**Test crop PGPF strain Improvement References**

*Aspergillus ustus* Shoot growth, lateral root, root

development

hair numbers

chlorophyll content

chlorophyll content, photosynthesis

area, chlorophyll content

area, chlorophyll contents, photosynthetic rate

area, chlorophyll contents, photosynthetic rate

*Aspergillus* spp., *Alternaria* spp. Seed germination [55]

*Talaromyces wortmannii* FS2 Shoot fresh weight [40]

*T. longipile, T. tomentosum* Shoot dry weight, leaf area [57]

*Chaetomium globosum* CAC-1G Plant biomass, root-shoot growth [23]

*T. harzianum* T-75 Yield [58]

vigor

*Pe. viridicatum* GP15-1 Root-shoot length, biomass [35] *T. harzianum* GT3-2 Root-shoot growth [60] *F. equiseti* GF19-1 Root-shoot growth [61]

salinity

field

*Phoma* sp. GS8-2, GS8-3 Root-shoot growth [63]

*T. harzianum* T-22 Root growth, development [64]

*Phoma herbarum*TK-2-4 Plant length, biomass [41]

weight

*Aspergillus* spp. PPA1 Root-shoot length, biomass, leaf

*Exophiala* sp. *LHL08* Plant growth under drought and

*Phoma* sp. Root-shoot growth, yield in the

*A. fumigatus LH02* Shoot growth, biomass, leaf

*T. viride* Root-shoot length, plant dry

Shoot-root growth [28]

shoot-root growth, leaf area, leaf

Plant growth [16]

*Penicillium janthinellum* GP16-2 Shoot biomass, leaf number [33] *Pe. simplicissimum* GP17-2 Shoot biomass, leaf number [9]

[48]

[20]

[27]

[39]

[59]

[17]

[26]

[62]

[65]

[18]

[66]

*DOI: http://dx.doi.org/10.5772/intechopen.92338*

38335,

*Cicer arietinum A. niger* BHUAS01, *Pe. citrinum*

BHUPC01, *T. harzinum*

*Fusarium oxysporum* NRRL 38499, NRRL 26379 and NRRL

*Basella alba Fusarium* spp. PPF1 Germination, seedling vigor,

*Cucumis melo T. harzianum* Bi Germination, seedling health,

*Glycine max A. fumigatus* HK-5-2 Shoot growth, biomass, leaf

*Cucumis sativus Pe. simplicissimum* GP17-2 Root-shoot growth [4]

*B. chinensis A. niger* 1B and 6A Plant dry weight, N and P content [56]

*Pe. resedanum* LK6 Shoot length, biomass,

*Arabidopsis thaliana*

*Astragalus utahensis*

*Brassica campestris*

*B. oleracea* var. *capitata*

*Capsicum annuum*

GiSeLa6® (*Prunus cerasus × P. canescens*)

*Gossypium arboreum L* *Application and Mechanisms of Plant Growth Promoting Fungi (PGPF) for Phytostimulation DOI: http://dx.doi.org/10.5772/intechopen.92338*


*Organic Agriculture*

**4.1 Impact of PGPF on seed germination and seedling vigor**

on seed germination and seedlings growth of a wide arrays of hosts.

The most common form of growth promotion by PGPF is the augmented shoot in colonized plants. Shoot growth promotion has been shown by a great diversity of PGPF across a large number of plant species. Isolates of *Aspergillus, Trichoderma, Penicillium*, and *Fusarium* were capable of enhancing the shoot growth in model plant Arabidopsis [9, 20, 28, 33, 48]. Different species of *Aspergillus* are known to support shoot growth in chickpea [16], Chinese cabbage [56], cucumber [17], soybean [18, 65] and wheat [76]. Species of nonpathogenic *Fusarium* were reported to stimulate shoot growth in Indian spinach [27] and banana [29]. Application of barley grain inoculum of *Penicillium viridicatum* GP15-1 to the potting medium resulted in 26–42% increase in stem length, 37–46% increase in shoot fresh weight and 100–176% increase in shoot dry weight of cucumber plants [35]. Similarly, inoculation of cucumber plants with *Pe. menonorum* KNU3 increased cucumber shoot dry biomass by as much as 52% [36]. Stimulated shoot growth by *Penicillium* spp. was also reported in tomato [69], Waito-c rice [37, 38], chili [23, 39] and sesame [74]. Application of *T. longipile* and *T. tomentosum* increased shoot dry weight of cabbage seedlings by 91–102% in glasshouse trials [57]. Likewise, cottonseeds pretreated with *T. viride* showed four-fold increases in shoot length elongation and an almost 40-fold increase in plant dry weight compared to the control [66]. Augmented shoot growth by *Trichoderma* has also been reported in chickpea [16], wheat [79], maize [78], cucumber [60] and other plant species (**Table 2**). Isolates of *Phoma* were found to be an efficient stimulator of plant shoot [15, 41, 62]. A few hypovirulent *Rhizoctonia* isolates were able to induce significantly higher fresh leaves and stems weights in tomato plants grown in greenhouse [13]. Enhancement of shoot growth was also observed

**4.2 Impact of PGPF on shoot growth**

Seed germination and germinant growth are critical developmental periods of the young plantlet until it begins producing its own food by photosynthesis. Treatment with PGPF, particularly of the genus *Aspergillus*, *Alternaria*, *Trichoderma*, *Penicillium, Fusarium, Sphaerodes* and *Phoma* has been reported to improve seed germination and seedling vigor in different agronomic and horticultural crops (**Table 2**). Scarified seeds inoculated with spores from *Aspergillus* and *Alternaria* had significant increases in germination of Utah milkvetch (*Astragalus utahensis*) *in vitro*, and in greenhouse and fall-seeded plots near Fountain Green and Nephi [55]. The *Aspergillus*-treated seeds performed out seeds inoculated with *Alternaria*. An increase of 30% in seedling emergence was observed in cucumber plant raised upon the treatment of *T. harzianum* [47]. Application of *T. harzianum* also significantly increased seed germination, emergence index, seedling vigor and successful transplantation percentage in muskmelon compared to the untreated controls [59]. Early seedling emergence and enhanced vigor were observed in bacterial wilt susceptible tomato cultivar treated with *T. harzianum*, *Phoma multirostrata*, and *Penicillium chrysogenum* compared to untreated controls [34]. The culture filtrate of *Penicillium* was as effective as the living inocula in improving seed germination of tomato [70]. Significantly, higher germination and vigor index were observed in Indian spinach, when seeds were sown in sterilized field soil amended with wheat grain inoculum of *Fusarium* spp. PPF1 [27]. *Sphaerodes mycoparasitica*, a biotrophic mycoparasite of *Fusarium* species, improved wheat seed germination and seedling growth *in vitro* compared to *T. harzianum,* while under phytotron conditions, both *S. mycoparasitica* and *T. harzianum* had positive impact on wheat seedlings growth in the presence of *F. graminearum* [12]. These results show the positive impact of PGPF

**70**


#### **Table 2.**

*Effect of different plant growth promoting fungi (PGPF) on seed germination, plant growth and yield in various plants.*

by *Talaromyces wortmannii* in cabbage [40], *Chaetomium globosum* in chili [23], *Colletotrichum* sp. in tobacco and *Exophiala* sp. in cucumber [26]. The results from these studies are consistent with numerous field and growth chamber experiments that have shown that PGPF inoculants can mediate shoot growth improvement.

**73**

conditions.

**4.5 Impact of PGPF on flowering**

*Application and Mechanisms of Plant Growth Promoting Fungi (PGPF) for Phytostimulation*

The plant growth promotion in some plant-PGPF interaction is occasionally associated with improvement in state and function of the photosynthetic apparatus of plants. Treatment with *T. longipile* and *T. tomentosum* increased leaf area of cabbage by 58–71% in glasshouse trials [57]. Tomato plants grown with HBNR isolates had significantly higher leaf fresh weight than control plants in greenhouse [13]. Arabidopsis grown in soil amended with *Pe. simplicissimum* GP17-2 and *Pe. janthinellum* GP16-2 were more greener and had approximately 1 more leaflet per plant than control plants 4 weeks after treatment [9]. *Penicillium* spp. also enhanced leaf chlorophyll content in cucumber and chili [36, 39]. Soil amendment with *Aspergillus* spp. PPA1 and *Fusarium* spp. PPF1 significantly increased leaf area and leaf chlorophyll content in cucumber and Indian spinach, respectively [27]. Improvement in leaf number, leaf area and leaf chlorophyll levels would contribute to increases in photosynthesis rate and net accumulation of carbohydrate in plants.

Roots are vital plant organs that remain below the surface of the soil. The root system is important for plant fitness because it facilitates the absorption of water and nutrients, provides anchorage of the plant body to the ground and contributes to overall growth of plants. Root functions as the major interface between the plant and the microbes in the soil environment. The bulk of previous studies have evidenced the immense ability of PGPF in enhancement of root growth in different plants (**Table 2**). Plants forming association with PGPF show faster and larger root growth resulting in a rapid increase in the root biomass [27, 35, 50, 57]. Moreover, root length, root surface area, root diameter and branch number are under direct influence of intimate interaction with PGPF. Application of *T. virens* ZT05 increased root length, root surface area, average root diameter, root tip number and root branch number of pines by 25.11, 98.19, 5.66, 45.89 and 74.42%, respectively [72]. *A. ustus* is known to cause alterations in the root system architecture by promoting the formation of secondary roots in Arabidopsis and potato [20]. In maize (*Zea mays*), *Trichoderma* inoculation enhanced root biomass production and increased root hair development [78]. The abundance in root hair formation significantly increases root surface area, suggesting that PGPF inoculants could enhance the potential for plant roots to acquire nutrients under nutrient-limited

The application of PGPF may influence the number, size and timing of flower in flowering plants. *Tagetes* (marigolds) grown with companion of *Pe. simplicissimum* flowered earlier and had greater flower size and weight [80]. Steamed or raw soil infested with *T. harzianum* hastened flowering of periwinkle and increased the number of blooms per plant on chrysanthemums [77]. Under greenhouse conditions, *T. harzianum* TriH\_ JSB27 and *Pe. Chrysogenum* PenC\_ JSB41 accelerated the flowering time in tomato [34]. Similarly, root colonization by the nematophagous fungus *Pochonia chlamydosporia* hurried flowering in *Arabidopsis thaliana* [81]. Root colonization by *Piriformospora indica* also results in early flowering in *Coleus forskohlii*, bottle gourd and *Nicotiana tabacum* [82]. Flowering time has commercial significance for crops and ornamental plants by shortening crop duration and improving productivity. A short duration crop would have several advantages over a long duration crop, even with equal total yields such as require less water, expose less to stresses and

*DOI: http://dx.doi.org/10.5772/intechopen.92338*

**4.3 Impact of PGPF on photosynthesis**

**4.4 Impact of PGPF on root growth and architecture**

*Application and Mechanisms of Plant Growth Promoting Fungi (PGPF) for Phytostimulation DOI: http://dx.doi.org/10.5772/intechopen.92338*

#### **4.3 Impact of PGPF on photosynthesis**

*Organic Agriculture*

*Helianthus annuus*

*Lycopersicon lycopersicum*

*Nicotiana tabacum*

*Pinus sylvestris* var. *mongolica*

*Saccharum officinarum*

*Sesamum indicum*

*Solanum tuberosum*

*Spinacia oleracea*

*Suaeda japonica*

*Triticum aestivum*

**72**

**Table 2.**

*various plants.*

by *Talaromyces wortmannii* in cabbage [40], *Chaetomium globosum* in chili [23], *Colletotrichum* sp. in tobacco and *Exophiala* sp. in cucumber [26]. The results from these studies are consistent with numerous field and growth chamber experiments that have shown that PGPF inoculants can mediate shoot growth improvement.

*Effect of different plant growth promoting fungi (PGPF) on seed germination, plant growth and yield in* 

**Test crop PGPF strain Improvement References**

content

*T. harzianum* T-22 Seed germination under stress [69]

growth

activity

*T. viride* Yield [73]

*F. equiseti* Plant biomass, root-shoot growth [75]

*Penicillium* sp. Sj-2-2 Plant length [38] *Cladosporium* sp. MH-6 Shoot length [24] *Pe. citrinum* IR-3-3 Root-shoot length [37] *Phoma herbarum* TK-2-4 Plant length [41]

growth.

growth

main and secondary roots

*A. niger* NCIM Shoot and total plant length ratio [76]

*F. equiseti* GF19-1 Plant biomass, root-shoot growth [71]

*Penicillium* spp. Seed germination, root-shoot

*T. harzianum* E15*, T. virens* ZT05 Seedling biomass, root structure,

*Penicillium* spp. NICS01, DFC01 Root-shoot growth, chlorophylls,

*A. ustus* Root-shoot growth, lateral root,

*T. harzianum, T. koningii* Plant biomass, root-shoot

*Sphaerodes mycoparasitica* Seed germination, seedling

*Vinca minor T. harzianum* Flowering, plant height, weight [77]

*Zea mays T. harzianum* T22 Shoot growth, area and size of

*Lactuca sativus F. oxysporum* MSA 35 Root-shoot growth, chlorophyll

Seed germination, seedling vigor [67]

Seedling emergence, vigor [34]

Yield [29]

Root-shoot growth, chlorophylls, soluble sugars, plant biomass

soil nutrients, soil enzyme

proteins, amino acids, lignans

root hair numbers

[68]

[70]

[15]

[72]

[74]

[20]

[4]

[12]

[78]

*Trichoderma* sp., *Aspergillus* sp., *Penicillium* sp., *Phoma* sp.,

*T. harzianum* TriH\_ JSB27*, Phoma multirostrata* PhoM\_ JSB17, *T. harzianum* TriH\_ JSB36*, Pe. chrysogenum* PenC\_ JSB41

*Alternaria* sp., *Phomopsis* sp., *Cladosporium* sp., *Colletotrichum*

*Fusarium* sp.

*Musa* sp. *F. oxysporum* V5W2, Eny 7.11o, Emb 2.4o

sp., *Phoma* sp.

The plant growth promotion in some plant-PGPF interaction is occasionally associated with improvement in state and function of the photosynthetic apparatus of plants. Treatment with *T. longipile* and *T. tomentosum* increased leaf area of cabbage by 58–71% in glasshouse trials [57]. Tomato plants grown with HBNR isolates had significantly higher leaf fresh weight than control plants in greenhouse [13]. Arabidopsis grown in soil amended with *Pe. simplicissimum* GP17-2 and *Pe. janthinellum* GP16-2 were more greener and had approximately 1 more leaflet per plant than control plants 4 weeks after treatment [9]. *Penicillium* spp. also enhanced leaf chlorophyll content in cucumber and chili [36, 39]. Soil amendment with *Aspergillus* spp. PPA1 and *Fusarium* spp. PPF1 significantly increased leaf area and leaf chlorophyll content in cucumber and Indian spinach, respectively [27]. Improvement in leaf number, leaf area and leaf chlorophyll levels would contribute to increases in photosynthesis rate and net accumulation of carbohydrate in plants.

#### **4.4 Impact of PGPF on root growth and architecture**

Roots are vital plant organs that remain below the surface of the soil. The root system is important for plant fitness because it facilitates the absorption of water and nutrients, provides anchorage of the plant body to the ground and contributes to overall growth of plants. Root functions as the major interface between the plant and the microbes in the soil environment. The bulk of previous studies have evidenced the immense ability of PGPF in enhancement of root growth in different plants (**Table 2**). Plants forming association with PGPF show faster and larger root growth resulting in a rapid increase in the root biomass [27, 35, 50, 57]. Moreover, root length, root surface area, root diameter and branch number are under direct influence of intimate interaction with PGPF. Application of *T. virens* ZT05 increased root length, root surface area, average root diameter, root tip number and root branch number of pines by 25.11, 98.19, 5.66, 45.89 and 74.42%, respectively [72]. *A. ustus* is known to cause alterations in the root system architecture by promoting the formation of secondary roots in Arabidopsis and potato [20]. In maize (*Zea mays*), *Trichoderma* inoculation enhanced root biomass production and increased root hair development [78]. The abundance in root hair formation significantly increases root surface area, suggesting that PGPF inoculants could enhance the potential for plant roots to acquire nutrients under nutrient-limited conditions.

#### **4.5 Impact of PGPF on flowering**

The application of PGPF may influence the number, size and timing of flower in flowering plants. *Tagetes* (marigolds) grown with companion of *Pe. simplicissimum* flowered earlier and had greater flower size and weight [80]. Steamed or raw soil infested with *T. harzianum* hastened flowering of periwinkle and increased the number of blooms per plant on chrysanthemums [77]. Under greenhouse conditions, *T. harzianum* TriH\_ JSB27 and *Pe. Chrysogenum* PenC\_ JSB41 accelerated the flowering time in tomato [34]. Similarly, root colonization by the nematophagous fungus *Pochonia chlamydosporia* hurried flowering in *Arabidopsis thaliana* [81]. Root colonization by *Piriformospora indica* also results in early flowering in *Coleus forskohlii*, bottle gourd and *Nicotiana tabacum* [82]. Flowering time has commercial significance for crops and ornamental plants by shortening crop duration and improving productivity. A short duration crop would have several advantages over a long duration crop, even with equal total yields such as require less water, expose less to stresses and

increase the availability of the land for subsequent cropping. This indicates that PGPF improve the plasticity of complex plant traits.

### **4.6 Impact of PGPF on yield**

PGPF show promising ability to promote growth through extensive improvements and betterment of fundamental processes operating in the plants, all of which directly and indirectly contributes to the crop yield increase. Inoculation of banana (cv. Giant Cavendish and Grand Nain) with *F. oxysporum* resulted in 20–36% yield increase in the field [29]. Soil treatment with *T. harzianum* alone or in combination with organic amendment and fungicide significantly improved seed yield in pea [83] and chickpea [58]. Similarly, soil treatment with *T. viride* produced significantly the highest number of fruits per plant, number of seeds per fruit, fruit weight and dry weight of 100 seeds as compared to untreated control [84]. The beneficial association of plants with nonpathogenic binucleate *Rhizoctonia* spp. resulted in increase in yield of carrot, lettuce, cucumber, cotton, radish, wheat, tomato, Chinese mustard and potato [13, 45, 46]. These results demonstrate that PGPF hold great promise in the improvement of agriculture yields.
