Abstract
This study was undertaken to ascertain the genetic differences in 32 genotypes for pod yield and its component raits, and morpho-physiological characters, namely carbon isotope discrimination (?13C), enrichment of oxygen isotopes (?180), specific leaf area (SLA) and SPAD chlorophyll content (SCMR) that are known to influence water-use efficiency (WUE) in groundnut. Highly significant genotypic differences (P<0.01) were observed for ?13C, ?180, SLA, SCMR, harvest index, shelling percent, plant height, and pod, kernel and haulm yields and total dry matter production. A strong inverse relationship of SCMR with SLA (r = -0.626, P<0.01) and ?13C (r = -0.552, P<0.01) was observed. Very high broad sense heritability estimates (81%) were obtained from SCMR. ?13C was positively associated with harvest index (r = 0.535, P<0.01) and its association with haulm yield (r = -0.617, P<0.01) and total dry matter (r = -0.522, P<0.01) were negative. The cluster analysis revealed that genotypes ICR 11 and JUG 28 were the most closely related, and GG 20 and JUG 13 were the least related genotypes. This has significance for future breeding due to the potential to produce transgressive segregrants through hybridization of these distant genotypes. The genotypes that involved ICGS 76 as one of the parents in their pedigree scored very high SCMR values.
