Quantifying Temperature Effects on Plant Development Rates and Quality of Compact Container-grown Pepper

Abstract

The mean daily temperature effects on plant development rates and quality of compact container-grown pepper were evaluated. Compact pepper cultivars Fresh Bites Yellow and Hot Burrito were grown in greenhouses at 18 to 26 °C (Expt. 1) and 20 to 30 °C (Expt. 2) under supplemental high-pressure sodium lighting and a 16-hour photoperiod. The number of days to first open flower, to first ripe fruit, and from flower to ripe fruit were measured and the development rates calculated by taking the reciprocal (e.g., 1/day). Temperature effects were predicted by fitting a nonlinear exponential function that included the base temperature (Tmin) and maximum developmental rate (Rmax) parameters. Plant quality attributes were measured during Expt. 2. As the temperature increased, the times to flower and fruit decreased (i.e., developmental rates increased) for both cultivars. The estimated Tmin was 13.3 °C for ‘Fresh Bites Yellow’, and that for ‘Hot Burrito’ was 9.3 °C, whereas the Rmax was similar between cultivars (averages of 0.0488 at flower, 0.0190 at fruit, and 0.0252 from flower to fruit). ‘Fresh Bites Yellow’ and ‘Hot Burrito’ grown at ≈25 °C had a relatively short crop time, compact canopy, large fruit size, and high number of fruits per plant at finish. Compact peppers are new crops being grown by greenhouse floriculture operations for their ornamental and edible value, and the information from this study can help growers schedule these crops to meet critical market windows and determine the impacts of changing the growing temperature on crop timing and quality.