ICRISAT Archival Report 2006 - The seedlings of success in the ...

conditions, fully expanded quadrifoliate leaves of 45 days old plants (third or fourth from the top) of each line were
excised and planted in sand cultures (roughly 1.5 cm thick) in plastic trays (39.5 × 29 × 7 cm). In each tray, 20
leaflets were planted and the trays were covered with plastic bags and incubated in the growth chamber at 24 ºC and
85% relative humidity. The LLS inoculum (30000 spores ml -1 ) was sprayed on both the surfaces of each leaflet.
Some plants showed latent period (LP) of 30 - 36 days after inoculation and 2 - 5 lesions with minimum lesion
diameter (6.0. Data
showed that the segregation is very high in the crosses, and there were no differences in the parent line plants (Table
4).
Table 4. Area under the disease progress curve (AUDPC), disease score, and leaf area damage (LAD) in F 3
progenies (ICRISAT, Patancheru, 2006 rainy season).
Crosses
No of AUDPC Score * LAD (%) *
Progenies Mean Min Max Mean Min Max Mean Min Max
(JL 24-P2 x ICG
11337-P2) 166 1567 500 2581 6 2 9 51 5 95
(JL 24-P5 x ICG
11337-P5) 18 1687 816 2485 6 3 8 41 10 80
(JL 24-P6 x ICG
13919-P6) 134 1411 568 2265 6 2 9 43 5 95
(JL 24-P8 x ICG
13919-P8) 118 1534 511 2459 6 4 9 46 10 95
ICG 11337 1 752 647 935 3 3 3 9 6 10
ICG 13919 1 719 593 813 3 3 4 10 6 12
JL 24 1 1779 1553 1987 9 9 9 100 95 100
* Score = Late leaf spot disease score on 1 - 9 scale; LAD = Leaf area damage (%) at 110 days after sowing.
Based on mean data of all the plants in each progeny, four progenies and two parent lines showed resistance to LLS
with score of 3.0, 38 progenies showed a disease score of 4.0, 79 had score of 5.0, and the remaining progenies
recorded a score of 6 - 9 on 1 - 9 scale. Leaf area damage was 7.5 - 95.5%. Area under the disease progress curve
(AUDPC) was observed in a range from 615 to 2285 among the progenies at 110 days after sowing. Taking the
mean data of all the plants and progenies in each cross, it was observed that the AUDPC, disease score and leaf area
damage were more than double in JL 24 and in crosses, compared to ICG 11337 and ICG 13919 parent lines (Fig.
4a, b).
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