Identification of diverse groundnut germplasm: Sources of early maturity in a core collection

A groundnut core collection was evaluated in two seasons to identify 21 early maturing landraces. Phenotypic diversity of these 21 early maturing landraces was assessed in three rainy and five post-rainy seasons, along with the three known sources of early maturity (Chico, Gangapuri, and JL 24). The new sources differed in 8 of 14 morphological traits studied. Of the 14 agronomic and 2 quality traits studied, 8 yield and yield-component traits were evaluated at two harvest dates. The landraces matured in 80–90 days after sowing (DAS), similar to Chico and Gangapuri (80–90 DAS) and earlier than JL 24 (90–95 DAS). Four new early maturing landraces [ICG 4558 (India); ICG 4890 (Argentina); ICG 9930 (Zimbabwe); ICG 11605 (Bolivia)], with predominantly three to four seeds per pod, were identified as additional sources for breeding confectionery groundnut varieties. Correlation coefficients between the observations made at the two harvest dates for the seven yield traits were ≥0.71, indicating a single observation is sufficient at 75 DAS or 90 DAS in initial characterization. Correlation between pod yield and 100-seed weight was significant in all the eight seasons individually and overall at 90 DAS. Presence of additional phenotypic diversity in the new early maturity landraces was detected. Principal component analysis (PCA) using the first 10 PC scores delineated the 21 landraces into three clusters. The formation of these clusters could neither be explained on the basis of geographic areas of landraces collection nor on the basis of botanical varieties. This might reflect the nascent variation acquired by the landraces in their secondary habitats, under ecologically similar conditions, independent of their countries of origin. Landraces in clusters 2 and 3 showed a wide range for several agronomic traits, indicating their usefulness in breeding programs for developing early maturing high yielding broad based cultivars.