Sampling strategies for developing Indian sesame core collection

Various stratified random sampling strategies were compared for developing a core collection of indigenous sesame Sesamum indicum L accessions. Twenty diversity groups (strata) representing 3,129 Indian sesame accessions were used for the study. The Shannon Diversity Index (SOI) pooled over 19 descriptors was used as the measure of the diversity. Simple random sampling alongwith six stratified random sampling strategies were compared for varying sample fractions ranging from 5 to 30%. Stratified random sampling was always superior to simple random sampling. Of the six stratified sampling strategies, a genetic diversity dependent strategy with sampled accessions from various strata direcdy proportional to the product of the diversity and logarithm of the size of the strata (GL strategy) appeared to be the best strategy. A 10% sample fraction could be determined as the suitable sample fraction, invariably for all sampling strategies, serving both objectives of germplasm management and use.