Indian Journal of Plant Physiology

An experiment was conducted during post rainy season of 2001–02 at Regional Agricultural Research Station, Tirupati with 111 spanish and 110 virginia groundnut genotypes. The genotypes were screened for moisture stress and high temperature tolerance and were classified into 3 groups, viz. low, medium and high for SPAD chlorophyll meter reading (SCMR), SLA, chlorophyll fluorescence ratio and membrane injury. Majority of the spanish genotypes had medium SCMR (45–50) and SLA (125–150), while most of the virginias had high SCMR (>50) and medium SLA (125–150). Majority of the spanish and virginia genotypes screened had high membrane injury of >60%. Significant variation was observed between the genotypes for SCMR, SLA, chlorophyll fluorescence ratio and membrane injury. Spanish genotype TIR-21 showed less reduction in F_v/F_m ratio when exposed to temperatures of 45°C (1.13% reduction) and 55°C (22% reduction), while virginia genotype TIR-34 maintained high F_v/F_m ratio at temperature > 50°C. Genotypes TIR-20 and JAL-31 showed a higher reduction of 84 and 82% respectively in F_v/F_m ratio when exposed to 55°C. Spanish genotype JAL-07 had a low membrane injury (37%). Incidentally, it also maintained high SCMR (52) and low SLA (101.6cm² g⁻¹), indicating that it can tolerate both water deficit and high temperature. However, this genotype showed more reduction (62%) in F_v/F_m ratio at 55°C. Virginia groundnut CSMG84–1 showed low membrane injury (34%). Thus the genotypes TIR-21, TIR-34, JAL-07 and CSMG 84–1 are better for higher temperatures and hence can be recommended for the specified situation in order to increase the yield potential under high temperature conditions.