Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 2011
Publication Date: June 1, 2012
Citation: Preece, J.E., Smith, J.L. 2012. Phenotypic comparisons between wild relatives and cultivars of kiwifruit, persimmon, mulberry, and olive at the National Clonal Germplasm Repository, Davis, CA. Acta Horticulturae. 948:175-180. Interpretive Summary: The National Clonal Germplasm Repository (NCGR) for Tree Fruits, Nut Crops and Grapes is a United States Department of Agriculture-Agricultural Research Service (USDA-ARS) research unit that is located at the University of California Davis. It is one of about 20 national repositories located in various states and Puerto Rico that constitute the National Plant Germplasm System (NPGS). The NPGS has more than 530,000 plant accessions including the approximately 6600 accessions at the Davis NCGR. Much of the collection consists of wild relatives of Mediterranean species that are important horticulturally and grow well in the northern California climate. There are no cultivars that are under patent protection at the NCGR; rather, there are heirloom cultivars that were never patented, or are off patent; advanced breeders’ lines; and plants that were propagated from plants growing in the wild (wild relatives). The collection includes Actinida (kiwifruit, 78 accessions), Ampelopsis (grape relative, 21 accessions), Diospyros (persimmon, 133 accessions), Eriobotrya spp. (loquat, 35 accessions), Ficus (fig, 302 accessions), Juglans (walnut, 646 accessions) Morus (mulberry, 58 accessions), Olea (olive, 148 accessions), Pistachia (pistachio, 259 accessions), Prunus (stone fruit and almond, 1457 accessions), Pterocarya (wingnut, 25 accessions), and Punica (pomegranate, 160 accessions). In addition to maintaining and increasing the collection, the NCGR has research and service missions. The plant collection serves as a living laboratory, supporting numerous research projects. The NCGR houses molecular biology, plant tissue culture, and fruit evaluation laboratories along with greenhouses, screen houses, and a lath shade house. All support active research. The service component has a focus of providing plant material to researchers worldwide. This leads to better understandings of relationships among plants, increased knowledge of propagation methods and pathogens, and development of new cultivars with improved traits. Wild relatives can serve as a pool of genes to help solve problems, such as drought and other environmental stresses, pathogens, and insects. Because the collection contains plants from various natural and cultivated populations, it has utilization in elucidating evolutionary (phylogenetic) relationships. This paper focuses on phenotypic descriptions of kiwifruit, persimmon, mulberry, and olive. This is an example of data collected on a portion of the collection in both the field and laboratory.
Technical Abstract: Phenotypic traits were characterized for 23 wild species and 4 cultivars of 4 clonal fruit crops including, Kiwifruit (Actinidia), Persimmon (Diospyros), Mulberry (Morus) and Olive (Olea). Across all four crops, the wild species varied distinctly, especially when compared with the cultivars. The wild kiwifruit relatives exhibited notable differences in their flower and fruit characteristics such as: anther color, fruit skin color, smaller flower diameter and fruit size, less fruit pubescence, and generally earlier harvest dates. The wild persimmon relatives were diverse in their fruit characteristics and had earlier or later harvest dates than ‘Fuyu.’ The wild mulberry relatives produced smaller fruit with lower titratable acidity and variable soluble solid content. The wild olive relatives differed chiefly from cultivars in leaf and fruit characteristics including: leaf color, leaf curvature, smaller fruit size, a reduced flesh to pit ratio, and earlier harvest dates.