Phenotypic diversity in cold-tolerant peanut (Arachis hypogaea L.) germplasm

Tolerance to low temperature is an important prerequisite for optimal performance of peanut (Arachis hypogaea L.) in a number of temperate peanut-growing environments. One hundred fifty-eight peanut accessions belonging to five botanical types, known to be tolerant to low temperature (12°C) at germination, were evaluated for phenotypic diversity for 15 morphological traits in the 2001 rainy season and for 15 agronomic and two seed quality traits in the 2001 rainy and 2001/2002 post-rainy seasons. Analysis of data, using the residual maximum-likelihood approach indicated that variance components due to genotypes were significant for all traits in the rainy and for all but two traits in the post-rainy season. Clustering based on scores of nine principle components delineated four clusters. The cold-tolerant genotypes and the standard control cultivars in the four clusters differed in mean, variance, and range both during rainy and post-rainy seasons for a range of agronomic traits, indicating the diversity among the clusters. The cold-tolerant accessions were superior to control cultivars for several agronomic traits compared with their respective controls in both the rainy and post-rainy seasons, so their use in breeding should result in genetically diverse cold-tolerant high-yielding peanut cultivars.