ABSTRACT

Lenses are a group of pulses having a socio-economic and nutritional significance. The study was conducted on two fields of Lens culinaris in Constantine region contaminated with molds, had the objective to put a relationship between pathogenic molds associated with these plants and their environment. This study revealed the presence of 20 genera in soils (Absidia, Acremonium, Alternaria, Aspergillus, Bysochlamyces, Chaetomium, Cladosporium, Emericella, Eurotium, Fusarium, Mucor, Paecilomyces, Penicillium, Peronospora, Phytophotora, Pseudalesheria, Scopulariopsis, Scytaldium, Trichoderma and Ulocladium) and 20 genera also in plants (Absidia, Acremonium, Alternaria, Aspergillus, Botrytis, Chaetomium, Cladosporium, Cylindrosporium, Curvularia, Eurotium, Fusarium, Myrothecium, Onychocola, Phytophthora, Pseudalescheria, Penicillium, Peronospora, Rhizoctonia, Trichoderma and Ulocladium). They contribute approximately 54% of the total micropopulation enumerated in studied samples. The development of these pathogenic strains is governed by environmental conditions namely the chemical elements in soil, pH, electrical conductivity, Nitrogen, Carbon and saturation. The results we have obtained shows that the chemical variations ground contribute to the right development fungi and their transfer to plants

Key words: Lens culinaris, soil, fungi.

Studied area

 

The field experiments were conducted in 2011 and 2012 on two agricultural soils: AIN SEMARA and BARAOUIA situated in the North East of Algeria.

 

Sampling procedures in the study area:

 

Soil sampling

 

Soil samples taken at 5, 10 and 15 cm from the soil surface were collected from four locations in the vicinity of the two areas (AIN SEMARA and BARAOUIA), in sterile paper bags. The soils collected are ground and passed through 0.2 mm sieve and were used for the analysis.

 

Plant sampling

 

Lentil plants from Metropole variety (20 samples), were collected from different places in fields infected by many types of mold. These plants were collected in sterile paper bags.

 

Physical and chemical properties analysis

 

The physiochemical properties are executed in a laboratory of soil chemistry. The important parameters studied are: available Nitrogen, Organic Carbon, Electrical conductivity and pH value.

 

Available Nitrogen

 

The dosage of Nitrogen is effected using berthelot reaction (Krom, 1980; Searle, 1984, EN ISO 11732 (2013)) modified by Belahrache (Benlahrache, 2013).

 

Organic Carbon

 

The Walkey and Black (1934) method described by Nelson and Sommers in 1982 is used for assaying the organic carbon in simple soils.

 

Electrical conductivity

 

The assay method involves wet ground with 100 g of distilled water slurry. The paste obtained was centrifuged at 300 revolutions / min for 30 min. In the end, the temperature of the float is noted in the resistance, is measured after adjusting the temperature to 25°C, using a conductivity meter (Anonymous, 1954).

 

pH

 

The method relies on the preparation of a solution (diluted suspension) of ground 10 g and 25 mL of distilled water, after magnetic stirring, the pH is measured at room temperature using a pH meter (Boudoudou et al., 2009).

 

Mycoflora isolation

                       

From soil (Dilution plating method)

 

To isolate the fungi from the soil sample, 1 g was diluted in 9 mL of saline solution. 1 mL of the diluted sample was poured and spread on Petri plates containing sterilized PDA medium. The inoculated plates were incubated at a temperature of 27°C for 3 days (Warcup, 1950). To prevent bacterial growth, one milligram of chloramphenicol was added to the medium.

 

From plants

 

Infected plants collected from the websites surveyed (AIN SEMARA and ABARAOUIA), was cut into small pieces of about 0.5 cm. The pieces are disinfected with sodium hypochlorite (2%) for 3 min, then rinsed several times with sterile distilled water and ethanol (70%) and dried between sterile filter paper, then placed in Petri dishes (5 piece / Petri plates) containing a culture medium PDA, MEA5 or MS. Finally, the Petri plates were incubated at 27°C for 4 days (Belabid et al., 2000).

 

Mycoflora identification

 

Colony colour, odor, morphology and growth rate were noted besides hyphal structure, spore size, shapes and spores bearing structures. They were compared with the standard works of Packer and Thomas (1990), Rinaldi et al. (1998), Gams et al. (1998), Botton et al. (1999), and Snavi (1999).

 

Presentation of data

 

The number of genera is referred to as genera diversity. Population density is expressed in terms of colony forming unit (CFU) per gram of soil with dilution factors. In order to assert the dominance of the genus in site, percentage contribution was worked out as follows:

 

 

 

 

 

 

 

 

Physical and chemical properties analysis

The results of the physical and chemical properties analysis of two soil samples (with different depth), have revealed that soils of AIN SEMARA and BARAQUIA are rich in organic matter (>1) and by consequence Carbon and Nitrogen. In addition, the organic matter is rich in carbon and poor in Nitrogen. Furthermore, results of pH analysis show that values are slightly alkaline (between 7.69 and 7.86). The measure of electrical conductivity (EC) and the salinity factor are indicated to lower than 1; which means that the soils were not salty (Table 1).

Mycoflora isolation

From soil

Altogether, six soil samples from two different stations representing the entire Constantine district were examined for fungal diversity. The study resulted in the presence of 44 species of fungi belonging to 14 genera from BARAOUIA and 42 species of fungi belonging to 16 genera from AIN SEMARA (Figure 1).

Indeed, the soil sample of BARAOUIA is characterized by the presence of 68.21% Deutromycetes, 20.43% Ascomycetes, 6.82% Oomycetes and 2.27% of Phycomycetes and Zygomycetes. The soil samples of AIN SAMARA contain less Deutromycetes (50%), Ascomycetes (35.72%) and Zygomycetes (9.52%) but more Oomycetes (4.76%) (Figure 2).

The quantitative comparison of genera shows that high percentage belongs to the Fusarium, Penicilum and Aspergilus in two studied areas. By contrast, the other genera have variable percentages in both sites (Figure 3).

The dominant genera from the field soils of BARAOUIA are Fusarium and Penicillium (9 species  each),  followed by Aspergillus (8 species), Phytophtora (3 species), Acremonium, Alternaria, Chaetomium, Cladosporium and Paecilomyces (2 species each) and finally Mucor, Peronospora, Scopulariopsis, Trichoderma and Ulocladium (1 species each); whereas in AIN SEMARA soils, the dominant species were Aspergillus (9 species), Penicillium (5 species) and Fusarium and Absidia (4 species each) followed by Eurotium and Scytalidium (3 species each), Alternaria, Paecilomyces, Phytophtora and Ulocladium (2 species each), and finally Acremonium, Bysochlamyces, Cladosporium, Emericella, Pseudallesheria and Trichoderma (1 species each).

From plants

A total number of 110 species belonging to 18 genera of fungi: Absidia, Acremonium, Alternaria, Aspergillus, Botrytis, Chaetomium, Cladosporium, Cylindrosporium, Curvularia, Eurotium, Fusarium, Myrothecium, Onychocola, Penicillium, Peronospora, Phytophtora, Pseudalescheraia and Rhizoctonia (Figure 4), were isolated from lentil plants (root, stem and leaf) in two areas of BARAOUIA and AIN SEMARA. These genera are classified in six divisions for BARAOUIA (Ascomycetes 66.24%, Basidiomyctes 1.78%, Deutromycetes 12.52%, Oomyctes 1.78%, Phycomycetes 12.5% and Zygomyctes 3.57%) and four divisions for AIN SEMARA (Ascomyctes 79.63%, Basidiomyctes 1.85%, Deutromycetes and Phycomycetes 9.25%).

The major genus in the area of BARAOUIA is Fusarium (9 species) and Alternaria and Apergillus (8 species each). The other genera have a variable number of species: Phytophtora (7 species), Penicillium (4 species), Cladosporium, Curvularia and Ulocladium (3 species each), Absidia, Acremonium and Chaetomium (2 species each) and finally Botrytis, Cylindrosporium, Myrothecium, Peronospora and Rhizoctonia (1 species each). The Alternaria was the major genus with 11 species in the area of AIN SEMARA, followed by Fusarium (8 species), Aspergillus (6 species), Curvularia, Penicillium and Phytophtora  (5 species  each),  Ulocladium (4  species),

 

Acremonium, Onychocola and Trichoderma (2 species) and finally Rhizoctonia (1 species) (Figure 5).

 

 REFERENCES