Sorghum Diseases in India

Grains of all the F1S were brown and possessed
the tannin-containing testa layers; all
were resistant to molds. All the F2s segregated
into white-, red- (without the testa layer), and
brown-grained (with the testa layer) (Fig. 1).
Few segregates for each F2 population were
white-grained; only 12-27% of the total F2 population
was in this category (Table 1). Whitegrained
F2 segregates resistant to grain mold
(TGMR = 3 or below) were also very few compared
to red- and brown-grained segregates
(Figs. 2, 3).
We selected all white-grained F2 segregates
with Threshed Grain Mold Rating (TGMR) of 3
or less but selected only a few highly mold-resistant
red-, and brown-grained segregates with
TGMR of 2. The selected mold-resistant F2 segregates
were advanced during the postrainy sea­
276
500
400
300
200
100
0
Crosses:
1. IS 14384 x ICSV 1
2. IS 14384 x SPV 104
3. ICSV 1 x IS 14385
4. SPV 104 x IS 14385
5. IS 14388 x ICSV 1
6. IS 14388 x SPV 104
White-grained
Red-grained
Brown-grained
1 2 3 4 5 6
Crosses
Figure 1. Frequency distribution of white, red, and brown grained F2 segregates derived from
each of six crosses between colored grain and white-grain sorghums.
sons and screened and reselected for mold resistance
during rainy seasons 1983 and 1984. Selection
and advancement of red- or brown-grained
F2 segregates proved very useful as a number of
them were heterozygous for grain color and
therefore segregated for white-grained types;
these were screened and selected for GM-resistance
in later generations.
Evaluation in Advanced Selections
Advanced mold-resistant selections were evaluated
for resistance in a randomized-block design
with three replications at ICRISAT Center during
rainy season 1985. We included in the trial
(as controls) the three colored parental lines (IS
14384, IS 14385, and IS 14388), two white-grained