Variation in Transpiration Efficiency and Related Traits in a Groundnut Mapping Population

Transpiration efficiency (TE) was evaluated in groundnut genotypes JUG 26, ICGS 76, CSMG 84-1, ICGS 44, ICGV 86031, TAG 24 and ICG 2773 using the dry-down method. Pot-grown plants were irrigated to 90% field capacity then subjected to drought stress (i.e. irrigating plants with 70% of the water lost the day before the onset of drought stress) at 28 days after sowing (DAS). Significant variation among the genotypes for TE was evident, with TAG 24 and ICGV 86031 showing the lowest and highest values of TE, respectively. The soil water content where transpiration began to decline relative to the control varied among the genotypes, and these threshold values were negatively correlated to TE. In another dry-down experiment, 318 F8 recombinant inbred lines (RILs) obtained from a cross between ICGV 86031 and TAG 24 were also characterized, along with their parents, for TE. Substantial variation was observed among the RILs for transpiration, TE and specific leaf area (SLA) before and after the imposition of drought stress, and for SPAD chlorophyll meter readings (SCMR) before, during and at the end of drought stress. ICGV 86031 recorded greater TE and SCMA, and lower SLA than TAG 24. The analysis of TE values for the RILs revealed that the trait segregated transgressively and was governed by polygenes. The heritability value was highest for SLA, followed by SCMR. The heritability values were low for TE and transpiration. SLA and SCMR can be useful as alternative indices when the direct biomass-based evaluation of TE is not possible

R Serraj et al., 'Variation in Transpiration Efficiency and Related Traits in a Groundnut Mapping Population', International Arachis Newsletter(24), pp.42-45, International Crops Research Institute for the Semi-Arid Tropics, 2011