Evaluation and Characterization of a Genetically Diverse Musa Germplasm Core Subset

The USDA-ARS, Tropical Agriculture Research Station is responsible for curating germplasm of several regionally and internationally important agricultural crops.  Evaluation and characterization of Musa (bananas) genetic resources are an important component of programmed research.   In a global collaborative effort lead by Bioversity International, a select group of genetically and morphologically distinct Musa spp. germplasm accessions (the ‘Taxonomic Reference Collection’ or TRC) were evaluated and characterized over two cropping cycles.  Following greenhouse acclimatization, four in-vitro propagated plants for each of 34 accessions provided by the Bioversity International’s global Musa collection (also called the International Transit Centre - ITC) were field-established at the USDA-ARS, TARS Isabela research farm on June 17^th, 2010.  Beginning at flowering and during the mother cropping cycle, data was collected for a total of 32 descriptors with an additional 15 images taken at key developmental stages. During the second cycle (1^st ratoon) a more comprehensive set of descriptors (121) collected for all accessions were gathered.  During the mother and first ratoon growing cycles, environmental data as well as important agronomic traits (e.g., bunch weight, number of fruits, and cycling time) we evaluated.  Guidelines, which included IPGRI’s (now Bioversity International) 1996 version of ‘Descriptors for Banana’, were provided to use as a reference during the field exercise.  As the TRC included diverse genetic groups of Musa spp. germplasm accessions, the range in descriptors varied greatly.  At the TARS, four of the original 34 accessions appeared failed to grown ‘normally’ and/or did not flower.  Interpretation of descriptors was not always straight forward; therefore some adjustments in data collection methodologies were incorporated.  Descriptor records and images from the TARS evaluation site have been summarized and shared with Bioversity International personnel who are in the process of collating data from all other participating collaborators worldwide to assess trait stability across agro-environments.  Preliminary results of the summarized information across international sites indicate that standardization of cultural practices and a clear interpretation of the descriptors by curators (of diverse native languages) collecting the data is critically important in order to compare and summarize across sites.  Unique accessions in the TRC have been included in the permanent collection at TARS and are available for distribution in limited quantities for research and educational purposes.