Sorghum Diseases in India

70
60
50
40
30
20
10
0
Floaters (%):
1 = 0 to 10% floaters
2 = 10 to 20% floaters
3 = 20 to 30% floaters
4 = 30 to 40% floaters
5 = 40 to 50% floaters
6 = 50 to 60% floaters
7 = 60 to 70% floaters
8 = 70 to 80% floaters
9 = 80 to 90% floaters
10 = 90 to 100% floaters
1 2 3 4 5 6 7 8 9 10
Figure 4. Frequency distribution of floaters (%) among white, red, and brown-grain F2 segregates
derived from a cross between IS 14384 (red-grained) and ICSV 1 (white-grained) sorghums.
vanced selections were calculated. Here again
floater and dehulling recovery (0.8087 and -
0.8381, respectively, P = 0.01) were highly correlated
with mold resistance. Tannin was not
correlated with mold resistance (0.1801), since
the advanced selections did not have the testa
layer and were low in tannin content. Flavan-4ol
was highly correlated (-0.6612, P = 0.01)
with mold resistance, confirming reports (Jambunathan
et al. 1986) that high flavan-4-ol was
responsible for resistance in low-tannin coloredgrain
sorghums. All the white-grained, moldresistant
advanced selections had zero or small
amounts of flavan-4-ol.
We evaluated the stability of mold resistance
and grain hardness in six low-tannin lines at
ICRISAT Center during rainy season 1987. We
scored mold resistance and determined floater
percentage of the grains of each of these lines at
physiological maturity, and at 1, 2, and 3 weeks
Floaters (%)
White-grained
Red-grained
Brown-grained
after physiological maturity (Table 4). In general,
severity of mold increased and grain hardness
decreased from physiological maturity to 3
weeks after physiological maturity. The increase
was very small for the colored-grain mold-resistant
IS 14384. Grain mold scores and floater percentage
values of ICSV1 and IS 14332 were very
low and at physiological maturity not significantly
different from IS 14384, but increased significantly
during the first week of physiological
maturity. This suggests that for genotypes to be
mold-resistant their grains must remain hard
and vitreous in the field under wet and warm
conditions—the ideal environment for grain
mold development. Sorghum grains with a hard
and vitreous endosperm are also known to be
least susceptible to storage weevils. However, it
was reported that grains with a harder, more
vitreous endosperm were less digestible than
those having soft endosperm. Studies on grain
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