2019 ASHS Annual Conference

Plant breeders must rapidly and accurately phenotype extensive numbers of field-grown plants across environments to identify superior plants or populations and make selections. Trait phenotyping and associated labor, time and resources serve as the bottleneck of the breeding pipeline and one of the primary constraints in plant breeding. This bottleneck further intensifies for data collection of physiochemical and fruit quality traits, which typically involve laborious postharvest processing and laboratory assays. Relatively little research has been done on fruit phenotyping with portable hand-held instruments that are easy to use, are non-destructive and robust to withstand real-time field conditions. The objective of our multidisciplinary study was to evaluate the potential of a recently industrialized postharvest quality spectrophotometer, Felix, to be implemented as an in-field high-throughput phenotyping tool for fruit quality and physiochemical traits integral in tomato and pepper breeding. In replicated field experiments during summers of 2017 and 2018 in Davis, CA, we studied traits of pH, soluble solids and carotenoids in tomato and shrink, pericarp thickness, and carotenoids in pepper. Genetic material for tomato was comprised of inbred cultivars and introgression lines containing chromosomal introgressions from water-stress tolerant wild tomato Solanum habrochaites accession LA1777 in a S. lycopersicum inbred processing tomato cultivar E6203 background. Genetic material for pepper was comprised of diverse hybrid and open-pollinated cultivars of New Mexican chile, yellow wax and sweet bell peppers. Primary approach of our study involved partial least squares regression (PLSR) as a chemometric (computational chemistry) tool to build trait-based regression models using visible and near-infrared spectroscopy data from Felix. Secondary approach assessed patterns in the spectroscopy data based on variables of in-field irrigation treatments and fruit color. Tertiary approach evaluated associations between wavelength-specific spectroscopy data and plant variables such as genotypes, water treatment, and genotype x water treatment interaction. Results of our study revealed 1) the scope of Felix’s usage in tomato and pepper fruit quality breeding, and 2) insights into the complex relationship of vis-NIR spectroscopy with fruit biology, in-field environmental conditions, and genetic diversity.