Evaluation of a hand‐held spectrophotometer as an in‐field phenotyping tool for tomato and pepper fruit quality

Phenotyping for vegetable fruit quality traits can involve laborious postharvest and biochemical assays, decreasing efficiency of data collection. Portable devices that are easy to use and withstand in‐field conditions to non‐destructively and accurately quantify internal fruit quality traits would greatly enhance efficiency in breeding programs. We evaluated a hand‐held quality spectrophotometer, the Felix‐750, as an in‐field tomato (Solanum lycopersicum L.) and pepper (Capsicum annuum) high‐throughput phenotyping tool. Fruit quality traits included pH, soluble solids, carotenoids, and shrink in germplasm grown in replicated split‐plot field trials. Germplasm included elite inbred cultivars and introgression lines of tomato, and diverse hybrid and open‐pollinated cultivars of pepper. Our study employed a multi‐faceted approach to evaluate the use of the Felix‐750 in a plant breeding program. Our approach included chemometrics and trait‐based partial least squares regression modeling, and examination of patterns in the λ‐specific spectroscopy data based on variables relevant to genetic, fruit, and environmental factors using principal component analysis and biplots. Results of our study revealed: (a) the scope and limitations of the Felix‐750 in fruit quality trait assessment based on the range of predictive power of partial least squares models; (b) insights into the complex relationships of spectroscopy data with genetic diversity, fruit biology and biochemistry, and factors related to environment. Additional research on the Felix‐750 is needed to determine its potential applications at early and later stages of a breeding pipeline. We also suggest researchers explore more advanced chemometric tools and 3‐D fruit hyperspectral imaging approaches.