Iron deficiency chlorosis (IDC) is common among groundnut grown in calcareous and alkaline soils in India, China and Pakistan and causes considerable reduction in pod yield. To identify genetically diverse IDC tolerant accessions, the mini-core collection of groundnut representing geographical diversity was evaluated for IDC response over 2 years in iron-deficient calcareous soils. Enormous genetic variability was evident in the mini-core collection for IDC tolerance-related traits such as a visual chlorotic rating (VCR) and SPAD chlorophyll meter reading (SCMR) across five growth stages. Several IDC tolerant sources belonging to different botanical varieties such as hypogaea bunch (ICG # 5051, 6766, 5286, 6667, 4538, 14008, 5663, 9842, 11855), hypogaea runner (ICG 10479), fastigiata (ICG 10890) and vulgaris (ICG # 11651, 118) were identified. Among the six botanical varieties of groundnut, hypogaea bunch types were found most tolerant to IDC and this is the first report in groundnut. The IDC tolerant sources identified were irrespective of their country of origin. The principal component analysis based on VCR, SCMR, pod yield and its related traits revealed five major principal components that explained 80% of the total variation. The biplot generated using PC1 and PC2 revealed a distinct separation of IDC tolerant genotypes from the susceptible ones. The hierarchical clustering using five major principal components revealed seven major clusters that were mainly based on IDC response of the accessions.

Within the cultivated peanut species (Arachis hypogaea L.), there are two subspecies comprising six botanical varieties, and the effect of botanical taxon on oil content and fatty acid composition variability is unclear. To gauge the variability, 83 peanut accessions were analyzed for oil content (expressed at 0% moisture) and fatty acid composition. We found that within the subsp. hypogaea, var. hypogaea contained a much higher amount of oil in seeds than did the var. hirsuta Köhler (520 vs. 473 g/kg, P < 0.05); within the subsp. fastigiata Waldron, the vars. aequatoriana Krapov. & W.C. Gregory and vulgaris Harz contained a similar amount of oil in seeds (491 g/kg), not significantly different from other botanical varieties, but var. fastigiata contained a higher amount of oil (500 g/kg) than the var. peruviana Krapov. & W.C. Gregory (483 g/kg). In terms of the fatty acid composition, oil from seeds of var. hypogaea contained much more oleic acid than did var. hirsuta (491 vs. 377 g/kg, P < 0.05), but much less palmitic acid (97 vs. 138 g/kg, P < 0.05%) and linoleic acid (308 vs. 402 g/kg, P < 0.05). Oil from seeds of var. vulgaris contained much more oleic acid than did var. aequatoriana (437 vs. 402 g/kg, P < 0.05), but much less linoleic acid (346 vs. 380 g/kg, P < 0.05). Significant negative correlations of oleic with palmitic and linoleic acids were detected. The information on the oil content and fatty acid composition variability among botanical varieties would be useful for peanut breeders seeking germplasm containing both high oil content and proper fatty acid composition.