S05 - Session O1 - Optimization of packaging for transport and storage of ornamental young plants - Model selection for oxygen consumption rates

Authors: Lieven Van de Vondel *, An Vermeulen, Annelies Christiaens, Marie-Christine Van Labeke, Peter Ragaert, Frank Devlieghere

Propagation by cuttings or micropropagation is essential for many ornamental plants. Between the young-plant phase and the production phase transport and/or storage is often necessary which might lead to quality loss. In the Agro-Food Industry, equilibrium modified atmosphere packages (EMAP) have proven their usefulness in prolonging the shelf life of minimally processed fruits and vegetables while minimizing quality loss. In this concept, respiration is reduced by low oxygen (3-5%) and increased carbon dioxide (5-10 %) concentrations in the package. The ornamental industry can also benefit from the advantages of EMAP . Effeciently selecting the right packaging properties requires knowledge of the respiration rate of the plants at the desired storage temperature. In hermetically closed bottles containing azalea cuttings or Echinacea in vitro plantlets, the oxygen concentration in the headspace was measured as a function of time. Bottles were simultaneously stored at five different temperatures ( 2, 5, 8, 10, and 14 °C for azalea and 15, 20, 23, 27, and 31°C for Echinacea). The initial headspace composition consisted of 10% O2/ 90% N2. For the headspace oxygen evolution, linear polynomial regression models were fitted and selected for both species based on (1) the significance of the model coefficients, (2) (over)fitting by PRESS and AIC-values, and (3) trends in the standardized residuals. Next, the temperature-effect on the model parameters was estimated with an Arrhenius equation. Finally, a nonlinear mixed-effects model was developed to estimate the oxygen concentration as a function of time and temperature per plant species. For both plant species, a third-degree polynomial with temperature-dependent coefficients performed best according to the AIC-values. Including a random-effect for the intercept and the linear coefficient and in the case of Echinacea also the quadratic coefficient improved the models . The derivative of the models with respect to the time can be used to determine respiration rates.