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

equired for disease development. Diseases (LLS and rust) were scored on a 1 - 9 rating scale (1 = highly resistant,
and 9 = highly susceptible) at 89 and 105 days after sowing.
Development of LLS and rust was uniform throughout the infector rows, and 100% infection was observed in the
susceptible controls. Highly significant differences were observed among the genotypes in all the trials against LLS
and rust. For all the trials, coefficient of variation was in the range of 4 to 22% for LLS, and 5 to 15% for rust . Of
101 breeding lines tested, none of the test lines was resistant to LLS. Twenty-four lines showed an overall disease
severity score of 4.0. Another 16 lines had a score of 4.5, 29 lines were scored 5.0, and 15 lines rated as moderately
resistant (score 5.5) (Table 1). Eighty-eight of these lines showed good resistance to rust (disease score of 2); 11
lines scored 2.5 to 3; and the remaining two lines ICGV 05092 recorded 8.0 and ICGV 06160 scored as 6.5 at 105
days after sowing (Table 1).
Table 1: Evaluation of advanced breeding lines for late leaf spot and rust resistance (ICRISAT, Patancheru,
2006 rainy season)
Disease severity rating
Trial
No. of lines LLS
Rust
tested 1-3* 4-6* 7-9* 1-3* 4-6* 7-9*
EFDRGVT (SB) 11 Nil 10 1 11 Nil Nil
EFDRGVT (VB) 5 Nil 5 Nil 5 Nil Nil
AFDRGVT (SB) 15 Nil 14 1 14 Nil 1
AFDRGVT (VB) 16 Nil 16 Nil 16 Nil Nil
PFDRGVT (SB) 28 Nil 24 4 27 Nil 1
PFDRGVT (VB) 26 Nil 25 1 26 Nil Nil
Total 101 Nil 94 7 99 Nil 2
*Disease score on a 1 - 9 scale, where 1 = highly resistant, and 9 = highly susceptible for LLS and rust.
Preliminary evaluation for resistance to foliar diseases: Two foliar disease-resistant groundnut variety (PFDRG -
VT) trials consisting of 164 lines were screened against LLS and rust. Six lines showed resistance to LLS with a
score of 3.0, while 121 had a score of 4 - 6. For rust, 137 lines showed high levels of resistance (disease score 2.0).
The remaining lines had a score of >3.0 on a 1 - 9 scale.
Farid Waliyar, Lava Kumar, SN Nigam and R Aruna
Performance of F 2 to F 6 populations for resistance to LLS and rust under field conditions: Five breeding
populations (F 2 to F 6 , 118 lines) were evaluated for resistance to LLS and rust under field conditions during the 2006
rainy season in an un-replicated, 9 m row plot, with 60 cm inter-row spacing, and 10 cm distance between the plants.
TMV 2, a highly susceptible cultivar to both LLS and rust, was sown in infector rows after every five test rows.
Forty-five days after sowing, plots were inoculated by spraying 30 L of mixed suspension of P. personata conidia
and P. arachidis urediniospores. One day after inoculation, perfo-irrigation was provided daily for 30 minutes in the
evening up to 30 days to favor disease development. All the populations were evaluated on a 1 - 9 rating scale for
reaction to foliar disease at harvest. The development of LLS was uniform throughout the infector rows. The
breeding populations were categorized as resistant (disease score 1 - 3), moderately resistant (disease score 4 - 6)
and susceptible (disease score 7 - 9). A few single plants from F 6 population showed moderate levels of resistance
to LLS.
Farid Waliyar, Lava Kumar, SN Nigam and R Aruna
Screening of advanced breeding lines for resistance to Aspergillus flavus infection and aflatoxin contamination:
During the 2005 post-rainy season, 106 advanced breeding lines were evaluated for resistance to Aspergillus flavus
seed infection and aflatoxin contamination. The breeding lines were planted in five separate trials in the A. flavus
sick plot. The fungal inoculum multiplied on sorghum and maize grains was applied in the soil at two-weekly
intervals during the crop growth period, and end of season drought stress was imposed 30 days before harvest to
facilitate seed infection. Harvesting was done manually and pods were sun dried for 2 - 3 days. Pods from each plot
were collected separately, shelled manually and kernel sub-samples were analyzed for A. flavus seed infection by
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