Fungal invasion of red clover roots in a soil naturally infested with a complex of pathogens: effects of soil temperature and moisture content
1991
Nan, Z.B. | Skipp, R.A. | Long, P.G.
A quantitative method employing tissue maceration and plating was used to determine the internal fungal flora of roots of red clover (Trifolium pratense) plants, 4, 8 and 12 weeks after sowing in field plots, and in pots of field soil kept at different constant temperatures (10, 15, 20 or 25 degrees C) and moisture contents (40, 60 or 80% of soil water holding capacity) in the glasshouse. In field plots, the total number of colonies isolated per root increased at each successive harvest whereas the extent of fungal invasion (number of fungal colonies g-1 root tissue) decreased. A similar decrease in the invasion of roots of plants in pots reflected a slow rate of fungal infection and an accelerating production of lateral roots. Plant growth in pots was greatest at 25 degrees C and 60% WHC but slowed in most treatments between 8 and 12 weeks as plants became potbound. The fungi which dominated at 4 weeks (Verticillium dahliae and Fusarium solani) were isolated most commonly from plants grown at 10 degrees C, while at 12 weeks most colonies of the dominant fungi (Cylindrocladium scoparium, F. oxysporum, F. solani, and Trichocladium basicola) were obtained from plants grown at 20 and 25 degrees C. Roots from soil at high moisture content (80% WHC) yielded more fungal colonies in total than those from less moist soil at 4 and 12 weeks, however, during the first 8 weeks, F. solani was most often recovered from dry soil (40% WHC). Since the root mycoflora of field-grown and pot-grown plants was similar, choice of appropriate soil temperature and moisture conditions for glasshouse experiments would allow simulation of events in the field.
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