Agriculture Reference
In-Depth Information
The lowest rate of growth of the fungus was recorded at 5°C. Beginning of the
growth in this variation was observed on the 8th day after sowing. Fungal colonies
reached the diameter of Petri dishes on 42th day, with sporulation recorded only on
56th day (Figure 11.2).
At a temperature of 10°C on the 4th day of the experiment, the diameter of the
colony was equal to 12.5 mm, and after 28 days Petri dish was completely occupied
by the fungus. In this variant sporulation happened much earlier—on the 16th day. The
fastest growth of
Fusarium nivale
Ces. colony was observed at 20°C. The active be-
ginning of growth was already evident on the second day, sporulation was observed on
the sixth, while on eighth day of the experiment the colony's diameter reached 90 mm.
20°С
10°С
5°С
Beginning of the growth
2 days
4 days
8 days
Start
sporulation
6 days
16 days
56 days
The diameter of the colony
87.7 ± 2.03 mm
33.0 ± 2.00 mm
90.0 ± 0.00 mm
FIGURE 11.2
Temperature dependence of the development of fungus Fusarium nivale Ces.
Development of snow mold is determined by weather conditions of the spring
period and is not observed every year, so any conclusion on plant resistance can only
be made in the years of strong manifestation of the disease. One of the conditions to
obtain reliable results in the determination of resistance is the creation of artifi cial
conditions ensuring optimal infection load. This background on the experimental site
was created by application into soil of an aqueous suspension of spores and mycelia
of pure 14-day culture of
Fusarium nivale
Ces. Infectious load was 10
6
conidia/ml
of inoculum (500 ml/m
2
of soil). Infection was carried out in autumn in the phase of
bushing out before snow cover. Estimate of snow mold infection of plants was carried
out 10 days after snow melting in the early resumption of the growing season accord-
ing to methodical guidelines of Kobylyansky [14], on a scale developed by Andreev
and Molchanova [15] and Geshele [16].
A study of infection in vivo under hard infectious background revealed that harm-
fulness of snow mold manifested in the reduction of such morphometric characteris-
tics of winter rye as plant height, leaf area, and productivity traits. Decline by more
than 50 percent was observed in leaf area per 1 m
2
, number of grains per plant, grain
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