Phenotypic diversity for morpho-agronomic traits in the US proso millet (Panicum miliaceum L.) core collection

Proso millet (Panicum miliaceum L.) is a short-season annual crop known for high water-use efficiency and drought tolerance. The low water requirement makes this ancient grain an excellent rotational crop for the winter wheat-based dryland cropping system in the High Plains of the United States. The genetic base of the commonly grown US cultivars is very narrow. Assessment of proso millet germplasm for agronomic traits is essential for its efficient utilization in the genetic improvement of this crop. The objectives of this study were to (1) characterize the US proso millet germplasm based on nine important morpho-agronomic traits and (2) classify the germplasm into clusters based on these morpho-agronomic traits. A total of 77 genotypes from 24 different countries were evaluated in the field during 2014 and 2015 at Scottsbluff and Sidney, NE. The genotypes showed significant variations for all the traits across locations. Many traits showed genotype × environment interactions and were highly correlated. Several genotypes were identified as sources of desired traits, such as maturity, lodging, and grain shattering. The genotypes formed six clusters based on morpho-agronomic data. Principal component analysis revealed that these nine traits explained maximum phenotypic variance and could be used as selection indices in proso millet breeding. This is the most comprehensive study of the US proso millet core collection based on morpho-agronomic traits and would be useful for developing improved proso millet cultivars.