Exposure to physical, chemical or biological stresses is an intrinsic characteristic of plant life not only in the natural environment but also under more or less controlled conditions in horticultural and agricultural systems. Globalisation and concentration of plant production throughout the world, on the one hand, allows for optimizing of growth conditions, but, on the other, increasingly involves post-harvest stress during storage and transport of intermediate and final products (Çelikel and Reid 2002;Kadner and Druege 2004). According to Levitt (1980), the term stress is used for any external factor capable of inducing a potentially injurious strain in the plant. With regard to the condition of the plant, plant stress can be described as a state in which increasing demands made on a plant lead to an initial destabilization of functions, followed by adaptive responses towards normalization, which may even lead to over-compensation of functions and improved resistance (Larcher 1995). However, if the acute tolerance or adaptive capacity is overtaxed, permanent damage or death may result. Within a network of hormonal cross-talk (Gazzarrini and McCourt 2003), ethylene production and signalling are highly involved not only in stress-induced symptoms of disturbed growth, senescence or injury, but also in acclimation processes which aid plant performance and survival.