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Monday, 4 June 2018

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In the present communication, the effect of seasonal changes, soil depths, amendment of soil with fungal spores, fungal culture filtrate, mycelial extract and certain plant materials on fungistasis property of some soil samples has been reported.

Materials and Methods:
Three localites, viz., forest area (F), cultivated field (C) and grassland locality (G), situated in close proximity, were selected for the present investigation. 100 x 100 x100 cm size pits were dug at three different places in each locality. The soil was sampled from eight different depths, viz., 0- 2 (1), 2 - 7 (2), 7 -12 (3), 12 - 17(4), 17-25 (5), 25 -35(6), 35 - 45 (7) and 45-60 (8) cms. The soil was aseptically collected from each locality in sterilized soil containers. Sampling of soil was done in summer, rainy and winter seasons of the year 1970 -71. The samples from the same depth of each locality were mixed together before assession of fungistasis and fungal population. For enumeration of soil fungistasis the method adopted was that of Lingappa and Lockwood (1963). Two fungi, Curvularia lunata and Fusarium nivale were selected as the test organisms. For assession of fungal population, the procedure adopted was as followed by Mishra (1966). The population was expressed on the basis of one g dry weight of the soil. The moisture content and organic matter content of the soil were determined as described by Piper (1966). In one experiment, the equal amount of sterilized soil (120°C for 2 hours) was amended with fresh cultures of Rhizopus nigricans, Mucor hiemalis, Trichoderma viride, Aspergillus fumigatus, A. flavus, A. niger, A. aculeatus, A. ochraceus, A. terreus, Cladosporium herbarium, Alternaria tennis, Curvularia lunata and Fusarium nivale separately. Ten circular pieces, each measuring 1cm diameter, of freshly sporing mycelial mat of the above fungi were mixed with 50 g of sterilized soil in each case. The plates were incubated at 25 + 2°C for 15 days and thereafter fungistasis was determined. The effect of culture filtrate of the above-mentioned fungi on fungistatic property was also studied. The fungi were separately inoculated in 250-ml sterilized conical flasks containing 100 ml of sterilized Czapek's liquid medium. The flasks were incubated at 25 +/- 2°C for 15 days and thereafter the liquid remained therein was filtered through Whatman paper No. 1. This liquid was designated as culture filtrate of a fungus. The filtrate was mixed with sterilized soil at the rate of 1 ml per 10 g of soil and the fungistasis was assessed by using C. lunata and F. nivale as test fungi. The fungal extract used was sterilised at 120°C for 15 min. Remaining mycelial mats in the above experiment were collected and were thoroughly washed with sterilized distilled water. The 5 g of material was mortared separately in 50 ml sterilized distilled water. The solutions were filtered and were mixed separetely with the sterilized soil at the rate of 1 ml per 10 g of soil. The soil was then packed into sterilized petri plates of equal size and was surface smoothed. This soil was tested for the fungistasis. For the study of fungistasis in sterilized soil caused by amendment of root, stem, and leaf of Argemone mexicana, Croton sparsifloyus, Ipomoea fistulosa, Equisetum species (Rhizome, stem, root), Launea species, Heliotyopium indicum and Nastaurtium species the plant materials were collected separately and were washed with several changes of sterilized distilled water. 100 g of each of the samples was thoroughly washed and mortared nicely and the pulp thus prepared was mixed separately at the rate of 1 gm per 10 gm of sterilized soil, The soil with plant material was kept for 8 days and the fungistasis of this soil was then studied. 

Different levels of inhibition in germination of fungal spores of Curvularia lunata and Fusarium nivale were observed in various soil samples obtained in different seasons. Fungistatic property of the different soil samples is described as follows:
Fungistasis in relation to cover vegetation: As evident from Figure 1, higher inhibition in the case of both the test organisms was recorded in forest area and the minimum values were noticed in grassland soil.
Fungistasis in relation to soil depth: With minor exceptions as detailed in Figure 1, in all the three seasons the inhibition in spore germination of the two test fungi was  highest in the soil samples obtained from upper layers. Increased soil depth resulted to a gradual decrease in fungistatic property. The pattern in cultivated locality, however, was different in winter season for both the test fungi (Figure 1).
Fungistasis in relation to seasonal changes: The higher fungistatic property in all the depths was observed in rainy season in forest and cultivated localities. Lowest values in corresponding depths in these localities were observed during summer season. In grassland locality, however, the trend was different. In this locality maxima for fungistasis was observed during winter whereas minimum values were obtained during summer. Both the test organisms behaved nearly alike except that percentage inhibition was higher in F. nivale. (Figure 1)
Fungistasis of soil amended with different fungal isolates: Fungistasis of various samples amended with different isolates varied differently. The maximum inhibition for both the test fungi was observed from the samples amended with A.flavus. Lowest values for C. lunata and F. nivale were observed from samples amended with Alternaria tennis and Aspergillus ochraceus respectively. Higher fungistasis was also observed in the case of Rhizopus nigricans, Mucor hiemalis, Trichoderma viride, Aspergillus aculeatus, A. terreus and A. niger for both the test fungi . As evident from Figure1, however, the percentage inhibition varied in different way for the two test organisms.

 Fungistasis o f soil amended with culture filtrate of different fungi: The culture filtrate of different fungal isolates induced different levels of inhibition. The maximum inhibition was noted in the soil sample to which culture filtrate of Aspergillus flavus was added. The lowest values for Curvularia and Fusarium were exhibited by the filtrates of C. herbarum and A. tennis respectively. Details are given in the Table 1.
 Fungistasis o f soil amended with mycelial extract o f the fungal isolates: Fungistasis property of soil samples amended with mycelial extract of 15-day-old cultures of different organisms differed in all the cases. The highest values for Curvularia and Fusarium were exhibited by the samples amended with the extract of A. flavus and lowest from A.tennis and F. nivale for C. lunata and F . nivale respectively. A sort of promotion in the germination of spores of both the test fungi was noticed in M. iemalis, T. viride, A. terreus, C. herbarum amended sets (Table 1).

Fungistasis o f soil amended with Plant materials: The different parts of the plants resulted to different degree of inhibition. The highest inhibition of fungal spore germination in both C. lunata and F. nivale was observed in the case of Argemone mexicana root, stem and leaf whereas the lowest value for both the fungi was obtained in the soil amended with different parts of Launea species. Other plants affected the inhibition of the spores of the two test fungi differently and the result is tabulated in Table 2.
Fungal Population and physico-chemical characters of the soil samples: Mycofloral population and physico-chemical characters of different soils were also determined. The variation in the fungal population of different soil samples, was both in quality and quantity. In the present paper mostly quantitative data have been incorporated (Figure 2).

 The dominant fungi in the different soil samples were Rhizopus nigricans, Mucor hiemalis, Trichoderma viride, Aspergillus niger, A. flavus, A. fumigatus, A. aculeatus, A. terreus, A. ochraceus, A. sydowi, A. nidulans, A. flavipes, Penicillium chrysogenum, Paecilomyces fusisporus, Cladosporium herbarum, Alternaria tenuis, Fusarium oxysporum, F. nivale and white sterile colonies. The organic matter content and moisture content of the different soil samples have been presented in the figure. (Original link)

Cited this as: Mishra R.R. and R.S. Kanaujia (1973): Observation of soil fungistasis III. Fungistasis in relation to soil depths, seasonal changes, soil amendments and physio-chemical characteristics of the soils. Plant and Soil. 38: 321-330. https://doi.org/10.1007/BF00779016


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