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

ICRISAT, 8 lines (2.6-1.6 ± 0.13 t ha -1 ) outperformed the best yielding control TAG 24 (1.3 t ha - ) and 13 lines (2.6 -
1.4 ± 0.13 t ha -1 ) significantly outperformed ICGV 91114 (1.0 t ha -1 ). When the same trial was evaluated under
irrigation, 7 lines (3.2 - 2.4 ± 0.16 t ha -1 ) outperformed the highest yielding control TAG 24 (2.1 t ha -1 ). The top
seven lines were common in both the environments. The best line ICGV 06436 came from (TAG 24 x ICGV 86300)
cross. In another trial, 7 out of 16 lines (2.9 - 2.1 ± 0.16 t ha -1 ) outperformed the best control ICGV 00350 (1.7 t ha -1 )
under rainfed conditions at ICRISAT. Under irrigation, none of the entries significantly outyielded the best control.
The best entry ICGV 06456 came from (AK 12-24 x ICGV 99032) cross.
Milestone: Physiological traits in 3 – 4 superior sources for drought tolerance dissected (VV/SNN/RA) 2010
An experiment was carried out to test the effect of a water deficit applied at different stages (early flowering, lateflowering,
and pod-filling) on pod yield and pod number. We used standard dry-down technique to apply the stress
at these stages. At each stage, stress was imposed according to dry-down technique, whereby the WS set was rewatered
when the relative transpiration was between 10 - 20% of control. We based the analysis on pod number per
plant relative to control. Water stress at mid-pod filling stage had no large influence on the pod number relative to
the control (pod number was 90% of control across genotypes), although a few genotypes such as ICR 48 and JUG
26 had relatively lower pod number under stress. By contrast, the relative pod number of plants exposed to stress at
early- and late-flowering was 63 and 76% of that of control across all genotypes tested, with a fairly large variation
across genotypes (35 - 93% for early-flowering stage, and 49 - 98% for late-flowering stage). During the earlyflowering
stage, the drought tolerant genotype ICGV 91114 was able to maintain 93% of control pod number.
Vincent Vadez
Activity 6B.1.2: Mapping and marker-assisted breeding for drought tolerance in groundnut
Milestone: QTL mapping of component traits of drought tolerance (TE) using available and suitable populations
(VV/RA/SNN/RKV) 2008
One population [ICGV 86031 (high TE) x TAG 24 (low TE)] has been phenotyped for two consecutive years for TE
in pot experiments in outdoor conditions during the Feb - April. Transpiration efficiency (TE) data have shown a
good agreement between years. Usual surrogates for TE [specific leaf area(SLA), and Spad chlorophyll meter
reading (SCMR), and the carbon discrimination ratio, Δ 13 C] have shown poor relation with the TE values, indicating
that, though the use of these surrogates remains valid to carry out large scale screening of germplasm, they have to
be used carefully for phenotyping, and measurement of TE itself is advised.
The parental genotypes of the mapping population were screened with >500 microsatellite markers and the
polymorphic markers were identified. Genotyping of the mapping population has been initiated. Based on
genotyping data of >50 markers on the population, a preliminary map-free linkage analysis has been undertaken.
The analysis revealed a few markers linked to TE, and to several surrogates (SCMR). However, these markers
explained 10% of the phenotypic variation. A larger number of markers would be needed in groundnut, as well as a
larger range of variation in TE, to find out robust QTLs for TE. In this direction screening of the parental genotypes
with a larger number of markers and genotyping of the mapping populations with more polymorphic markers is in
progress.
Vincent Vadez, Rajeev Varshney and L Krishnamurthy
Milestone: Mapping populations between contrasting parents developed to identify QTLs for component traits of
drought tolerance (root traits) (VV/RA/SNN) 2009
Screening for TE was undertaken in 2006 on 440 genotypes, including the mini-core collection of groundnut, which
showed over 5-fold variation for TE. This range is higher than the variation observed in 45 lines tested previously
(mostly breeding lines) to identify contrasting parents for TE, from which 2 segregating populations for TE have
been developed. Similarly the germplasm collection was genotyped with 21 microsatellite markers to assess the
molecular diversity. In a subset of the germplasm (189 accessions), the microsatellite markers yielded 3 to 20 alleles
with an average of 12.4 alleles per marker with an average PIC value of 0.84. A repeat of the TE screening will be
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