Influence of harvest date, 1-MCP treatment, and storage conditions on NDVI of European pear (Pyrus communis L.) 'Conference' throughout postharvest quality progress

In European pear (Pyrus communis L.) ‘Conference’, colour change during developmental progress is an important visual criterion to assess ripening stage related to eating quality. To maintain quality during storage and shelf-life, post-harvest application of 1-methylcyclopropene (1-MCP) is highly effective. Measuring the absorption spectra related to chlorophyll content and green colour, to calculate the normalized difference vegetation index (NDVI), is a promising non-destructive method to characterize ripening progress in pip fruit. The aim of this research was to characterize both, the NDVI progress throughout post-storage shelf-life conditions, and the influence of harvest date, storage conditions, and 1-MCP treatment on NDVI. Therefore, ‘Conference’ pear were harvested pre- and post-ethylene burst in commercial orchards located in semi-humid region in Germany over two consecutive years. Defect free pear were treated with 312 µg kg^‑1 1-MCP one day after harvest at 1°C±0.1 K. Additionally, pear treated with 1-MCP were exposed to 900 µg kg^‑1 ethylene simultaneously to 1-MCP, and with 100000 µg kg^‑1 after removal from CA-storage, respectively. The NDVI was measured in shelf-life (2015: 14 d; 2016: 10 d) at 20°C using hand-held spectrophotometer on single fruit. In both years, NDVI was highly influenced by harvest date (2015/2016: p<0.001) and storage conditions (2015: p<0.01; 2016: p<0.001) at removal from storage, whereas at the end of shelf-life, NDVI is more affected by treatment (2015/2016: p<0.001) and harvest date (2015/2016: p<0.001). Considering the results, measuring NDVI of ‘Conference’ pear provide an objective method to characterize developmental stage in situ.