Sorghum Diseases in India

tention is therefore being given to a type of resistance
expressed by a lower rate of disease development
over a certain period of time. The
evaluation of sorghum genotypes for this resistance
is made by creating artificial epidemics in
microfield test plots by inoculating a spreader
row of a susceptible cultivar with a spore suspension
of the pathogen. The inoculum multiplies
and disseminates toward the screening
plots. The interplot interference in the screening
plots is reduced by using a border row of a resistant
cultivar (Fig. 1). The disease intensity at
three different points in the screening plot (0.5,
3.0, and 5.5 m from the source of inoculum) is
measured on regular schedule as percentage of
leaf area affected by the pathogen, in accordance
to a standard disease scale (Sharma 1983).
The data were transformed into AUDPC (Area
Under Disease Progress Curve) (Vanderplank
1963). AUDPC values of some experimental hybrids
are listed in Table 3.
Values in the same column not followed
by the same letter are significantly different
(P=0.05), according to Duncan's test.
Table 3. Area under anthracnose progress curve of 12 sorghum cultivars, evaluated under decreasing
levels of inoculum, at three distances (0.5 m, 3.0 m, and 5.5 m) from a spreader row. 1
Table 3. Area under anthracnose progress curve of 12 sorghum cultivars, evaluated under decreasing
levels of inoculum, at three distances (0.5 m, 3.0 m, and 5.5 m) from a spreader row. 1
AUDP curve
Distance from susceptible border row
Cultivar (0.5 m) (3.0 m) (5.5 m)
Tx623 2501.0a 1890.0a 1885.3a
CMSXS 359 2080.0b 882.0b 858.7b
CMSXS 357 1660.2c 623.0c 591.5c
CMSXS 354 1473.5d 417.7d 327.8ef
CMSXS 366 1415.2de 306.8e 257.8g
CMSXS 352 1321.8c 417.7d 366.3e
CMSXS 356 1181.8f 563.5c 450.3d
CMSXS 358 995.2g 311.5e 291.7fg
CMSXS 357 976.5g 168.0f 112.0h
BR 302 962.5g 399.0d 364.0e
BR 007 B 862.2gh 430.5d 260.2g
BR 300 621.8i 179.7d 110.8h
1. Values in the same column not followed by the same letter are significantly different (P = 0.05) according to
Duncan's Multiple Range test.
1.0 m
Resistant 2
Cultivar
Resistant
Cultivar
Resistant
5.0 m
8.0 m
1.0 m
1. BR 001 (Tx 623) - Inoculated 40-50 days after sowing with
a spore suspension of 10 6 conidia mL -1
2. SC 283
Figure 1. Diagram of field plots used to evaluate
resistance to anthracnose in field conditions
under a disease gradient
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