Investigating Kiwiberry Fruit Quality and Germplasm Suitability

Abstract

Recent years have seen an increase in consumer demand and interest for a diversity of kiwifruit products (Harker et al. 2007; Jaeger et al. 2003; Latocha and Jankowski 2011). As market trends for local produce and consumer interest in diversifying food options increase in the United States, the opportunity to grow local fruit with novel characteristics becomes desirable. This interest has spurred investigation into kiwiberry as a new cold-hardy crop for Minnesota. The name kiwiberry is used to differentiate the species Actinidia arguta and A. kolomikta, which are two berry-sized, pubescence free, cold-hardy kiwifruit, from the fuzzy kiwifruit common in the marketplace A. chinensis (Hastings, 2018; Huang, 2016). Actinidia arguta and A. kolomikta are of particular interest for production in Minnesota as they have been reported to have relative ranges of cold-hardiness appropriate for cultivation in USDA zone 4 (-20 °F to -30 °F) (Lin et al. 202; Sun et al. 2020). Though there is increasing interest in these species, research is still needed to examine suitability of kiwiberry as specialty crops in Minnesota. This research utilized the established kiwiberry germplasm at the University of Minnesota (UMN) containing approximately 306 accessions of A. arguta, A. kolomikta, and their hybrids to address the following objectives: 1) determine consumer willingness-to-pay for kiwiberry; 2) improve curation of North American kiwiberry collections; 3) determine the impacts of harvest timing on fruit quality and storability for accessions of two kiwiberry species (A. arguta and A. kolomikta); and 4) examine whether the climacteric nature of kiwiberry allows for reduced spotted-wing drosophila (SWD) infestation pressure at harvest (as a function of harvest date or fruit firmness) and the subsequent impacts of infestation on fruit quality of two kiwiberry species (A. arguta and A. kolomikta) in the Upper Midwest. Consumers were willing to pay comparable prices for kiwiberries as other berries based on a second-price auction examining four kiwiberry accessions. A total of 262 kiwiberry accessions along with 106 National Plant Germplasm System (NPGS) accessions were fingerprinted using single nucleotide polymorphisms (SNPs) generated with genotyping-by-sequencing (GBS). Identity of 97 accessions were confirmed, of which 36 were previously unknown, and redundant accessions called. Fruit quality traits were observed for eleven known accessions over three years and optimal harvest timing for production was determined for each accession. Harvesting firm fruit was shown to reduce the infestation rates of spotted-wing drosophila (SWD) on fruits. Implications of this work are 1) identification of consumer segments interested in purchasing kiwiberry; 2) improved curation of UMN kiwiberry germplasm for more informed future breeding; 3) recommendations of harvest timing balancing fruit quality and storage; and 4) leveraging the climacteric nature of kiwiberry to reduce SWD infestation.