lmscussmNj

I I

DISCUSSION

During the present study, aeromycoflora in relation to leaf surface mycoflora of

Mentha arvensis Linn. was observed from March 2004 to February 2006. Overall 56

fungal species belonging to 28 genera of fungi were recorded from aeromycoflora and

leaf surface mycoflora. Meteorological factors play a very important role in the

distribution of mycoflora in the air as well as on the leaf surface.

Atmosphere is the reservoir of organisms, which contain a variety of micro­

organisms along with airborne fungal spores. Air is not a natural environment for the

growth and reproduction of microorganisms. It does not contain the necessary amount

of moisture and utilizable form of nutrients. Yet organisms are found in air, though they

have a transient survival. The number and kind of fungal spores in the air depends on

the activity in the environment and upon the amount of dust stirred up. Fungal spores

survive in the air for varying period of time. The quality and quantity of air borne fungal

spores vary, mainly depending on the source of contamination (soil, vegetation, organic

wastes of man, animals and plants etc.) in the environment and the locality as well as

climatic conclitions.

During the present investigation a total of 52 fungal species (643 colonies) were

recorded from the aeromycoflora over Mentha arvensis Linn. plants. the total fungal

species, maximum 40 species belong to Anamorphic fungi, 06 species to Mycelia sterilia,

03 species each to Zygomycotina and Ascomycotina, (Table-1). Out of the total

aeromycoflora, Zygomycotina contribute 3.10%, Ascomycotina 5.44%, Anamorphic

fungi 86.78% and Mycelia sterilia contribute 4.67%, (Table-XIII, Fig- 21).

Deuteromycotina was found to be the dominant fungal group of the aeromycoflora.

Similar results have also been reported by Jadhav and Tiwari (1994) after their studies of

aeromycoflora of Ravan village. They found that out of total mycoflora, Zygomycotina

contribute 13.04%, Ascomycotina 30.04%, Deuteromycotina 52.17% and Mycelia sterilia

4.34%.Naike and Pande (1994) reported the order of dominance of airborne fungal

groups after a two year survey (1990 & 1991) of aeromycoflora over sunflower fields at

115

Aurangabad as Deuteromycotina 77.46% and 79.80% followed by

Basidiomycotina15.00% and 8.81%, other types 4.87% and 9.65%, Ascomycotina 2.41%

and 1.70% and Zygomycotina 0.25% and 0.16%. The percentage contribution of different

fungal groups as reported by Sahu et al. (1994) was 7.14% for Zygomycotina, 42.85% for

Ascomycotina, 42.85% Deuteromycotina and 7.14% for Mycelia sterilia. Singh and Devi

(1994) studied the aeromycoflora over black gram field in Imphal and reported that the

Deuteromycotina spore types dominated the airspora by contributing the highest

percentage 68.9% in 1989 and 69.8% in 1990 followed by Ascomycotina 11.2% in1989

and 9.8% in 1990, and Zygomycotina 1.8% in 1989 and 1.40% in 1990. Sharma (2001) also

reported Deuteromycotina as dominated (57.55%) fungal group of the aeromycoflora

over Ocimum sanctum plants. This is also in agreement with the observations made by

Kalkar and Patil (1994). They studies the fungal airspora of a groundnut field at Nagpur

and reported maximum percentage contribution for Deuteromycotina (52.24%)

moderate for Basidiomycotina (6.56%) and minimum for Zygomycotina (2.84%). Jadhav

(1996) after his studies of the aeromycoflora over rice field at Balodabazar, Raipur

reported that the dass Deuteromycotina contributed the highest percentage 82.44% to

the total aeromycoflora, followed by Zygomycotina 8.55% and Mycelia sterilia8.70%.

The fungal population was not homogenous throughout the year and show

seasonal variations. Seasonal variations in the concentration of fungal species take place

due to changes in the meteorological conditions like temperature, relative humidity and

rainfall. Out of the 52 fungal species, maximum 35 species were recorded during winter

season (mean maximum temperature, 29.l"C and mean relative humidity, 62.1%)

moderate 25 species during rainy season (mean maximum temperature, 30.8°C and

mean relative humidity, 80.1%) and minimum 19 species during summer season (mean

maximum temperature, 38.4°C and mean relative humidity, 46.1%), (Fig-1). Jadhav and

Tiwari (1994) also reported maximum19 fungal types during winter, moderate 16

during rainy season and minimum 11 during summer season in Rawan village

Balodabazar. This is in agreement with the observations of Tilak and Sreeramulu (1967)

for Aurangabad, Rai (1969) for Varanasi, Ramalingam (1971) for Mysore, Bhati and Gaur

(1979) for Nagpur, Satpute et al. (1987) for Shilong; Manoharachari et al. (1988) for

Andhra Pradesh; Mari and Rajasab (1988) for Gulberga; Kumar and Prasad (1991) for

Nalanda; Singh and Rakhi (2003) for a Pharmacy in Hardwar. The maximum fungal

count in the atmosphere was during winter, moderate during rainy season and

minimum during summer season was also reported by Tilak and Bhalkc(1976-a & b)

116

from Aurangabad, Jagdishprasad and Narayan (1982) from Bangalore, Singh and Babu

(1983) from Delhi, Singh and Mishra (1988) around Gaya, Pandey and Tiwari (1991)

from Raipur, Tiwari and Sahu (1991-a) and Tiwari (1999) from Raipur, Sateesh et al.

(1993) from the atmosphere of Tiruchirapaili, Giri and Saoji (1996) from Nagpur, Bera

and Khandelwal (2002) over Southern ocean and Schirmacher Oasis, East Antarctica

during IX and XI Indian Antarctic Expedition, Udaya Prakash et al. (2003) from coastal

environment in Chennai, India, Padmanabhan and Nayar (2005) from sawmill

environment in Palakkad District, Kerala, India.

Similar observations were also reported by Mishra and Srivastava (1971-a) for

aeromycoflora over rice field, Kumar and Gupta (1976-b) for potato field, Ramchander

Rao (1987) for bajra field, Atiuri and Subba Reddi (1988) rice crop, Sahu (1995) for

spinach, Jadhav (1996) for rice, Sahu (1998) for wheat, Tiwari (1999) for air spora of

Raipur, Sharma (2001) for Ocimum sanctum plants, Aher et al. (2002) for groundnut field,

Lokhande and Pande (2004) for spinach field respectively.

During the course of investigation of aeromycoflora, maximum fungal incidence

(22 species with 106 colonies) was recorded during the month of January .in winter

season (mean maximum temperature, 27.5 'C and mean relative humidity, 65%) and

minimum 04 species in the month of May (mean maximum temperature, 41.1 'C and

mean relative humidity, 35%).(Fig-6). The average number of fungal species in the

atmosphere was minimum during summer (19) thereafter increasing in rainy season

(25) and reaching maximum level during winter season (35). (Fig-1) The total

aeromycoflora collected from experimental plants showed winter maxima (51.32%)

followed by rainy season (26.90%) and summer season (21.77%), (Table- XV). This was

probably due to favorable moderate humidity and temperature for the dispersion of

fungal spores. This is in agreement with the observation made by Mishra (1972), Naike

and Pande (1994) Singh and Rakhi (2003) etc.

The biggest toll of group Anamorphic Fungi, as a whole, dominated the entire

aeromycoflora. Cladosporium has been always a dominant fungus every where in the

world. The spores abundantly get trapped through out the year except April to July.

Cladosporium contributed 24 .88% of the total aeromycoflora (Table·IX). Cladosporium is

regarded as "Universal dominant" due to its dominance in showing high percentage

contribution in air by works in India and abroad. Next to C/adospo1ium, the airspora was

dominated by Aspergillus (22.55%), Curvularia (10.41%), Altcman·a (9.18%), Pmicillium

117

(5.28) and Fusarium (2.80%),(Table-IV). According to Gregory (1961) the high incidence

of Cladosporium, Aspergillus and other dominant types in the air was due to their high

degree of saprophytic and fruitlessness ability with passive spore liberations. The

natural and artificial mechanical disturbances and gentle wind current helped in

liberating enormous quantity of spores into the air. Sreeramulu and Ramalingam (1966)

have also reported Cladosporium as the most dominant spore type with a percentage

contribution of 50.64% to the total airspora after their two years survey over the paddy

fields at Vishakhapattanam. Kalkar and Patil (1994), Bhandari et al. (1999) also reported

similar observations. Cladosporium has also been reported as the dominant fungal species

from different countries and places of the world i.e. Canada (Paddy and Kapica, 1956);

England (Ainsworth, 1952; Gregory, 1961; Gregory and Hirst, 1957); West lndes

(Meredith, 1962).Pande (1976) also reported Cladosporium as a major component of air

spora with the percentage contribution of 34.24% to the total air spora at Nanded.

Ecological studies reveal that the members of the group Anamorphic fungi

Aspergillus (40.74%), Alternaria (22.22%), Curvularia (11.11%), Drechslera (11.11%),

Penicillium (11.11%), Phoma (11.11 %), Acremonium (7.40%) and Fusarium (7.40%) were

encountered as most frequent fungal genus of the total aeromycoflora.(Table-V)

Aspergillus was recorded as the predominant fungal genus in our studies. Singh and

Rakhi (2003) have made an aerobiological survey of a pharmacy in Hardwar and

reported that the dominant fungal forms of pharmacy air in 04 sampling sites were

Aspergillus (45.98%) followed by 03 species of Penicillium (16.43%), Cladosporium (6.5%),

Curvularia (6.34%) and Mucor (6.25%) where as Alternaria (2.5%), Fusarium (3.67%) and

Rhizopus (2.48%) were obtained in low frequency. Jadhav and Tiwari, (1994) reported

Aspergillus (95%), Curvularia (54%), Fusarium (41%) and Penicillium (8.33%) as most

frequent fungal types in their studies. Similar observations were also reported by Mishra

and Kamal (1971), Ramalingam (1971), Vittal and Punnuswami (1979), Roy (1988), Baig

(1991), Pandey and Tiwari (1991), Verma and Chile (1991), Ghani and Kale (1992), Singh

and Devi (1994), Jadhav and Tiwari (1994), and Millington & Carden (2004). Naik and

Pande (1994) reported the higher incidence of dominant spore types like Cladosporium,

Altemaria, Penicillium, Curvularia, Aspergillus etc in the air over sunflower fields. Uddin

(2004) reported that Penicillium and Aspergillus were most dominant saprophytes

followed by Curvularia and Cladospon·um.

During the present investigation, density of fungal species of aeromycoflora was

also observed (Table-VII). Maximum density was recorded for Cladosporium

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cladosporoides (13.33) followed by Curvularia lunata (3.75), Aspergillus japonicus (3.41}

and A. fumigatus (2.46). On the contrary minimum density 0.08 was observed for

Acremonium sp., Aspergillus terreus, A. parasiticus, Chaetomella raphigera, Penicillium

funiculosum and Trichurus spiralis.

The study of the percentage contribution of the fungal species to the total

aeromycoflora (Table-XV) reveals that the percentage contribution of different

fungal species varies with season. The maximum percentage contribution was

recorded for Zygomycotina in rainy season (1.86%), moderate in winter season

(0.93%) and minimum in summer season (0.31%), for Ascomycotina maximum in

rainy season (2.33%), moderate in winter season (2.02%) and minimum in summer

season (1.09%), for Anamorphic fungi maximum in winter season (46.19%),

moderate in rainy season (21.62%) and minimum in summer season (18.97%) and

Mycelia sterilia also show winter maxima (2.18%). During the present investigation,

maximum percentage contribution was recorded for Cladosporium cladosporoides

(24.88%) followed by Curvularia lunata (6.99%), Aspergillus japonicus (6.38%}, A. niger

(5.60%) and A. fumigatus (4.98%). The minimum percentage contribution 0.15% was

recorded for Acremonium sp., A. parasiticus, Chaetomella raphigera, Penicillium

funiculosum, and Trichurus spiralis. (Table-IX)

Oass wise percentage contribution to the total aeromycoflora was also observed

and maximum percentage contribution 86.78% was recorded for Anamorphic fungi

followed by Ascomycotina 5.44%, Mycelia sterilia 4.67% and minimum 3.10% for

Zygomycotina (Table-XIII). Kalkar and Patil (1994) also observed similar observations

over groundnut field at Nagpur and reported that the aeromycoflora was dominated by

Deuteromycotina (56.14%) followed by Basidiomycotina (6.56%) and Ascomycotina

(2.84%).The occurrence of the members of anamorphic fungi (Deuteromycotina) was

irrespective of weather conditions hence their spores were noticed throughout the

investigation period. This is in agreement with the observation made by Singh and Devi

(1994).

The class Zygomycotina was represented by 03 fungal species from

aeromycoflora i.e. Mucor lziemalis f silvaticus, Rhiwpus on;zae and Synceplwlastrum

racemoswn. Maximum percentage contribution 1.08% was recorded in August and then

decreased (Table-XIII). Jadhav (1996) reported 05 species of the class Zygomycotina i.e.

Circinella, Cumzinghamcl/a, Mucor, Plzytoptlzora and Rhiwpus. TI1e percentage contribution

119

gradually increased from July to August then decreased later on. In general the

members of the group Zygomycotina recorded from the aeromycoflora dominated in

the month of July to October, when there was a considerable amount of moisture

contents with high percentage relative humidity in the atmosphere. Obviously these are

prerequisites in inducing them to release spores in the atmosphere.

During the present investigation total 45 fungal species (597 colonies) were

recorded from the leaf surface mycoflora over Mentha arvensis Linn. plants. Of the total

fungal species, maximum 34 species belonging to Anamorphic fungi, 05 species to

Mycelia sterilia, 03 species to Zygomycotina and 03 species to Ascomycotina,(Table-11).

Similarly Prasad and Bilgrami (1969) isolated 28 fungi from the phylloplane of Litchi

chinensis. Mishra and Shrivastava (1970-c) recorded 23 fungi from yellow leaves and 22

fungi from green leaves of Oryza sativa. Sinha (1971) isolated 55 fungi from Capsicum

annuum and 44 fungi from Lycapersicum esculentum. Kumar and Sinha (1975) reported 36

fungi from leaf surface microflora of wheat. Tiwari (1977) recorded 54 fungal species

from the leaf surface of some solanaceous crop plants. Sahu and Tiwari (1988) isolated

31 fungal species from phylloplane mycoflora of Momordica charantia. Sahu et al. (1986)

has been reported 22 fungi from the leaf surface of Cymopsis tetragonoloba. Tiwari and

Sahu (1991-b) have isolated 30 and 21 fungal species from the leaf surface mycoflora of

pea. Sahu (1995) also isolated 16 fungal species from the leaf surface mycoflora of onion.

Bhat and Kaveriappa (1998) recorded 72 species on Myristica fatua and 61 on Myristica

malabarica . Almost similar findings were also reported by Sharma and Mukherjee

(1980), Tyagi et al. (1983) Shrestha and Sharma (1994), Sahu and Gupta (1995), Tiwari

and Sahu (1996, 1997), Tiwari and Sharma (2003) isolated 33 fungal species from the leaf

surface of Ocimum sanctum. Osono and Mori (2005) isolated 15 species from leaf surface

mycoflora of Suida controversa. Vegetation adds different fungal types in to the air and

their number vary according to vegetation type and weather conditions (Abdel, 2005).

Out of 45 fungal species, maximum 29 species recorded during winter season

(mean maximum temperature, 29.1 OC and relative humidity, 62.1 %) moderate 19 species

during rainy season (mean maximum temperature, 30.8T and mean relative humidity,

80.1 %) and minimum 15 species during summer season (mean maximum temperature,

38.4°C and mean relative humidity, 46.1%, (Table-XVIII & Fig-1). The maximum fungal

population was observed during winter season due to favourable temperatures and

relative humidity, moderate during rainy season and minimum during summer season,

120

possibly due to the unfavorable temperature and relative humidity for mycoflora. The

periodicity and occurrence of different fungal species in relation to meteorological

conditions are in agreement with the observations made by Tiwari (1977), Verma and

Khare (1987-b) . They also reported the occurrence of maximum fungal population

during winter season and minimum during summer season. These statements were

supported by Sahu (1995) and Tiwari and Sahu (1995-b). In winter season the

temperature ranges from 27.5 to 30.4 OC, which is optimum for the growth of most of the

fungal species hence the maximum number of fungal species recorded during this

season. The fungal population gradually decreases with the increase of temperature and

decrease with the decreases of relative humidity in the month of March to May.

During the study of leaf surface mycoflora, highest fungal incidence (15 species

with 117 colonies) was found during the month of January. Maximum 15 fungal species

were observed in the month of January during winter season (mean maximum

temperature, 27.5 OC and mean relative humidity, 65%) and minimum 03 species in the

month of May (mean maximum temperature, 41.1 OC and mean relative humidity,

35%), (Table- II, XVIII & Fig-8). Sahu (1996) has also recorded maximum number of

fungal species (34) in the month of January.

The average number of fungal species trapped from leaf surface were minimum

during summer (15) thereafter increasing in rainy season (19) and reaching maximum

level during winter season (29). (Fig-1) The total aeromycoflora collected over

experimental plants showed winter maxima (56.28%) followed by rainy season (24.79%)

and summer season (18.94%), (Table-XVI). This was due to favorable moderate

humidity and temperature for the dispersion of fungal spores.

The number of fungal species and the specific composition of the mycoflora were

affected by weather conditions. Some of the fungi were present throughout the season,

whereas others were exclusively associated with a particular climatic condition. This

tendency was found during the present investigation. This is in confirmation with

similar studies conducted by De menna (1959), Tiwari (1977), Tiwari and Sahu (1986,

1989-a, band 1991-a, b), Sahu and Tiwari (1985, 1988 and 1994), Sahu et al. (1986, 1988

and 1994), Verdavakis (1988), Chandel (1990), Sahu (1995), Tiwari and Sharma (2003).

Meteorological factors sud1 as temperature and relati\'e humidity were the

important factors influencing the leaf surface mycoflora. 1l1ese factors influence the

121

growth and sustenance of the micro-organisms of the phyllosphere region. Gregory

(1961), Kumar and Gupta (1976-a), Sahu and Tiwari (1985), Sharma and Tiwari (1981),

Navneet and Mehrotra (1987), Sahu et al. (1986), Tiwari and Sahu (1986, 1989-a, 1996 and

1997), Sahu et al. (1986), Pandey et al. (1989), Sahu (1995), Bhat and Kaveriappa (1998).

Dickinson (1967), Mishra and Kamal (1972), Dickinson (1976), Sharma and Mukhe*e

(1974-a & b), Devi et al. (2003), Devi and Singh (2003) reported that temperature and

humidity are the most important physical factors affecting the type and number of

fungal species found on the leaf surface. It was also observed that the fungal population

was not homogeneous throughout the year and showed seasonal variations.

Like aeromycoflora, the biggest toll of group Anamorphic Fungi, as a whole,

dominated the entire leaf surface mycoflora. Cladosporium has been always a dominant

fungus every where in the world. The spores are abundantly trapped through out the

year except in April May and July. Cladosporium contributed 46.06% of the total leaf

surface mycoflora. Cladosporium is regarded as 'Universal dominant" due to its

dominance in showing high percentage contribution in leaf surface by works in India

and abroad.

Ecological studies reveal that Aspergillus, Cladosporium, Curvularia, Alternaria, and

Penicillium were encountered as most frequent fungal types of the leaf surface

mycoflora. This is in agreement with similar studies of Sreerarnulu and Ramalingarn

(1963), Dickinson (1967), Sinha (1971), Kumar and Gupta (1976-a, b), Sahu and Tiwari

(1985 and 1994), Sahu et al. (1986), Sahu et al. (1988), Pandey et al. 1989), Sahu (1992 and

1995).

During the present investigation density of fungal species recorded from leaf

surface mycoflora was also observed. Maximum density was recorded for

Cladosporium cladosporoides (22.91) followed by Penicillium frequentans (4.41),

Aspergillus fumigatus (3.33), Mycelia sterilia white -I (1.91), Aspergillus niger (1.66)

and Chaetomella raphigera (1.16) and minimum density 0.08 was observed for

Rhizopus oryzae, Syncephalastrum racemosum, Alternaria radicina, A. triticina,

Arhtririnium sphaerospermum, Aspergillus carneus, A jlavus var. columnaris, Drechslera

australiensis, Drechslera biseptata, Fusarium equiseti, Papularia sp., Trichurus spiralis

and Mycelia sterilia white (iii).(Table-VIII)

122

The percentage contribution of the fungal species of the leaf surface

mycoflora was also observed. The percentage contribution of different fungal

species varies with season. During the present investigation, maximum percentage

contribution was recorded for Cladosporium cladosporoides (46.08%) followed by

Penicillium frequentans (8.88%), Aspergillus fumigatus (6.70%), Mycelia sterilia white-I

(3.85%) and Aspergillus niger (3.35%).The minimum percentage contribution 0.17% was

encountered for Rhizopus oryzae, Syncephalastrum racemosum, Alternaria radicina, A.

triticina, Arhtririnium sphaerospermum, Aspergillus carneus, A. flavus var. columnaris,

A. ochraceous, Drechslera australiensis, D. biseptata, Fusarium equiseti, Papularia sp.,

Trichurus spiralis and Mycelia sterilia white (iii). (Table-X)

Class wise percentage contribution to the total leaf surface mycoflora was also

observed and maximum percentage contribution 86.10% was recorded for

Anamorphic fungi followed by Mycelia sterilia 9.37%, Ascomycotina 3.85%, and

minimum 0.67% for Zygomycotina.(Table-14)

In leaf surface mycoflora the Cladosporium also was observed as the predominant

fungal genus in our studies. This fungus found to be growing on dead and decaying

leaves. As, the plants of Mentha arvensis Linn. are smaller in size and the number of

fallen decaying leaves is greater hence the incidence of Cladosporium over this plant was

found to be maximum. The Cladosporium species has also been described as the

dominant component of the atmosphere from Australia (Frey and Durie 1962); from

England (Ainsworth1952, Gregory 1973); from Canada (Pady and Kapica 1953); from

Jamaica (Meredith 1962) and from India (Sreeramulu 1961).

The nature and behaviour of fungal assemblages associated with leaf surface is

affected by a wide range of interacting meteorological factors. Living plants provide

wide variety of microbial habitats. One such habitat is the phylloplane (Bhat and

Kaveriappa, 1998). The phylloplane microflora is also reported to be antagonistic to

some pathogens (Blackman, 1981). The Leaf surface mycoflora survive under the

influence of environmental factors such as temperature, humidity and exudates of host

plants. A number of plant species have been reported to posses some natural substances

in their exudates and tissue sap, which were toxic to fungi. It is observed that a variety of

substances which may leach out from the aerial part of the plants. The substances whid1

leach out from plant surface along with water are called exudates. 1l1e composition of

the leaf surface mycoflora is influenced and to some extent regubted by the host

123

exudates on the leaf surface (Toppas and Wain, 1957; Bahadur and Sinha, 1966 & 1970;

Sharma and Sinha, 1971).

The result indicating that the percentage of germination of spores/conidia in all

the tested fungi was more in control in comparison to leaf exudates and leaf tissue sap

i.e. Alternaria altm1ata (96.52% ), Curvularia clavata (92% ), Curvularia ovoidea (84.09% ),

Curvulan·a lunata (80.28%) and Aspergillus niger (5.94%),(Fig -23). Sharma (2001) also

reported similar observations during the study of aeromycoflora in relation to leaf

surface mycoflora for Alternaria altm1ata (98%), Aspergillus niger (96%), Cladosporium

oxysporum (96%), Curvularia lunata (96%) and Nigrospora sphaerica (96%).

During the present investigation it is found that, the percentage of germination of

spores/conidia in all the tested fungi is higher in control (DW) and is inhibited gradually

in leaf exudates and leaf tissue sap as compared to control. In all cases the percentage of

germination is decreasing and percentage of inhibition of germination is increasing in

leaf exudates and leaf tissue sap. Chandrol and Karkun (2000) also reported the

antifungal properties of some plant extracts and reported that out of 40 plant species, the

extracts of 10 plants species showed marked inhibiting effect on germination while the

extracts of 15 plant species exhibited suppressive effect on germ tube elongation. Similar

findings have also been reported by Kono (1960), Kasuge and Hewitt (1964), Bahadur

and Sinha (1966), Dunn et al. (1969), Godferey (1976), Kamble and Bhale (2004), Mace

and Veechi (1973); Brillova (1971) and Godferey and Clements (1978) reported that leaf

exudates contain some specific substances which is responsible for the inhibition of

germination of spores/conidia The inhibition of germination is due to fungistatic

properties of leaf exudates (Toppas and Wain, 1957).

The percentage of inhibition of spore germination was less in case of leaf

exudates and more in case of leaf tissue sap. In case of Alternaria alt~?rnata, 24.51%

inhibition was observed in leaf exudates whereas in leaf tissue sap, inhibition was

75.85%. In Curvularia c/avata, inhibition was 31.50% in leaf exudates and 46.30% in leaf

tissue sap. Maximum inhibition was recorded in leaf tissue sap. In case of Curvularia

lunata, 30.12% inhibition was observed in leaf exudates whereas in leaf tissue sap,

inhibition was 45%. In Curvularia ovoidea, inhibition was 32.95% in leaf exudates and

52.50% in leaf tissue sap, (Table-XVII, Fig -23). Similar results were obtained by many

other workers. The inhibitory effect of leaf extracts of Ocimrmr sanctum plants on

124

Curvularia lunata, Pestalotia machrotricha, Mammaria echinobotryoides and Chaetomium

globosum was studied and reported by Chandra! and Karkun (2000). They also reported

the effect of leaf extracts Mentha viridis L. on the Curoularia lunata and found 43%

germination and 57% inhibition in it. Sharma (2001) reported fungistatic properties of

leaf extracts and leaf tissue sap of Ocimum ~anctum plants against Alternaria alternata,

Aspergillus nig~?r, Cladosporium oxysporum, Curoularia lunata and Nigrospora sphaerica.

On the basis of studies of genus wise overall aeromycoflora and leaf surface

mycoflora of Mentha aroensis Linn. plants, it is concluded that maximum contribution

(21.4%) was recorded for genus Asp!?rgillus with 12 species followed by genus Alternaria

with 06 species (10.71%), Penicillium with 04 species (7.14%), genus Curoularia, Drechslera

and Phoma each with 03 species (5.35%), genus Acremonium, Fusarium each with 02

species (3.57%) and remaining genera each with 01 species (1.78%). Pepeljnjak and

Segvic (2003) reported Cladosporium (65.3%-74%), Penicillium (4.43-13.9%), Alternaria (2-

4.7%) and sterile mycelium (7.4%-15%) were the most prevalent fungi in the air of all the

three climatic regions of Croatia, while Fusarium (20.3-36.2%) was the most prevalent

fungal genera on the plant samples. Abdel and A wad (2005) stated on the basis of their

studies on vegetation, a source of air fungal bio-contaminant that the Alternaria (7.4 -

59.9%) and Asp!?rgillus (11.2-38.9%), Penicillium (9.5-15%) and Cladosporium (7.78-17.5%)

were the predominant fungal genera found in all sampling sites. Alternaria (42-59.9 %%)

and Asp!?rgillus (11.2~38.9%), were the common fungal genera in the cultivated and

urban areas. Asp~?rgillus and Penicillium spores were present in the air of Derby

. throughout the year and often reached maximum monthly cumulative concentration in

the autumn, although they were occasionally the dominant spores in winter when total

spore concentration was low (Millington et al., 2005). The Penicillium showed a reverse

picture, their predominance increased with the termination of winter season and

simultaneously increased with the increase in temperature up to February. Only one

species of Penicillium (P. citrinum). was recorded in higher temperature of summer ' ' ' - - .

season.

The Cladosporium was the predominant fungal genus in our studies. It is a fungus

found to be growing on dead and decaying leaves. As the plants of Mentha mwnsis

Linn. are smaller in size and number of fallen decaying leaves is greater hence the

incidence of Cladosporium over this plant was found to be maximum. 1111:! CladoEporium

species has also been described as the dominant component of the atma5pherc from

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England (Ainsworth1952, Gregory 1973), from Canada (Paddy and Kapica 1953), from

Jamaica (Meredith 1962) and from India (Sreeramulu 1961). Uddin (2004) reported

Cladosporium as dominant genus, their concentration declined with the onset of summer

season. The genus Cladosporium is also reported as most common dominant fungal spore

type from different atmosphere by Sahu and Tiwari (1994), Sahu (1995), Tiwari et al.

(1995), Sharma (2001), from Raipur, Jadhav and Tiwari (1994) from Ravan village and

Jadhav et al. (1995) from Balodabazar.

The number of colonies of fungi recorded from aeromycoflora was greater than

the number of colonies recorded from leaf surface mycoflora in all the three season

(Table-1, III and Fig-1). The Number of colonies is inversely proportional to maximum

temperature. Minimum number of colonies (21) were recorded from aeromycoflora in

the month of May when mean temperature was maximum (4l.l"C) and mean R.H.

(35%) was minimum. On the contrary maximum number of colonies i.e. 106 was

recorded during the month of January, when maximum temperature and R.H. (27SC

and 65% respectively) was optimum. (Fig-7)

Similarly in case of leaf surface mycoflora, minimum number of colonies i.e.l2

recorded in the month of May when, mean temperature was recorded maximum

(41.1 "C) and mean R.H. was minimum (35%) because both factors have inhibitory effect

on fungal population. In leaf surface mycoflora, maximum number of colonies i.e. 117

was recorded in the month of January when mean maximum temperature (27.5) and

mean R.H. was optimum (65%). (Fig- 9)

The number of species recorded from aeromycoflora was also greater (52) than

the number of species recorded from leaf surface mycoflora ( 45) in all the three seasons

(Table-III, IV).Minimum number of species i.e. 04 was recorded from aeromycoflora in

May when mean temperature was maximum (4Lrq and mean R.H. was minimum

(35%). On the contrary maximum number of species i.e. 22 was recorded in the month

of January when mean temperature was maximum 27.5 and mean R.H. was optimum

(65%), (Fig-6). In case of leaf surface mycoflora, minimum number of fungal species (03)

was recorded in the month of May, when mean temperature was maximum (41.1"C)

and mean R.H. was minimum (35%). On the contrary maximum number of fungal

species (15) was recorded in the month of January, when mean temperature was

maximum 27SC and mean R.H. was optimum (65%). (Fig-S) Bhandari ct al. (1999)

reported that hot and dry climate during summer (mean maximum temperature, 39SC

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and mean relative humidity, 34.05%) decreased the spore load in the atmosphere, while

moderate climatic conditions (mean maximum temperature, 30.31 "C and mean relative

humidity, 62.42%) favored the spore load in the atmosphere. The low occurrence of the

fungi in the air during hot months have also been reported by Gregory (1973), Kamal

and Verma (1977) and Bhati and Gaur (1979).

From the aerobiological studies of aeromycoflora and leaf surface mycoflora it is

evident that, hot and dry climate during summer (mean maximum temperature, 38.4 "C

and relative humidity, 46.1%) decreases the number of fungal species in the atmosphere,

whereas the moderate climatic conditions during winter (maximum temperature, 29.1

"C and mean relative humidity, 62.1%) favored an increase in the number of species in

the atmosphere. Thus dry conditions have an adverse effect on the number of fungal

species in the environment. 11ris is in agreement with similar studies of Bhandari et al.,

(1999), Singh and Rakhi (2003). Ingold (1953) reported that the high temperature and

relative humidity check the spore discharge of some fungi. The low occurrence of fungi

during hot month (summer) has also been reported by Gregory (1973, Kamal and

Verma (1977) and Bhati and Gaur (1979).

Hence, it is evident from the above findings that the climatic factors do influence

the fungal airspora as they exhibit seasonal fluctuations but they are not the deciding

factors. Vegetation adds different fungal types in to the air and their number may vary . .

according to vegetation types and weather conditions. Other local and biological factors

like population, vegetation, buildings, garbage etc. also influence their occurrence in the

atmosphere. The contents of leaf exudates and leaf tissue sap variously affect the leaf

surface fungi. A number of plant species have been reported to posses one or more

natural substances in their leaves which were toxic to those fungi causing plant diseases.

The substances obtained from various plants have been reported to control a number of

fungal diseases of crop plants.( Singh et al.1967; Pandey and Pant, 1997 and Ghose et al.

2000)

Thus the ultimate aim of present work is to have a systematic record of fungal

flora types occurring over the aeromycoflora and on the leaf surface rnycoflora of

Mentha arvensis Linn. The above findings serve as a convenient basis for further

aerobiological studies over other economically important medicinal and agricultural

plants. 11ris kind of shtdy could serve an idea for forecasting as well as control of plant

diseases.

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