Screening ornamental pepper (Capsicum annuum L.) cultivars for temperature tolerance using pollen, physiological and seed germination parameters

Temperature affects reproductive potential, aesthetic and commercial value of ornamental peppers. In experiment one, temperature effects were assessed in 12 ornamental cultivars using in vitro pollen germination and tube length, and the physiological parameters, cell membrane thermostability, chlorophyll stability index and canopy temperature depression. In experiment two, seed germination rate and maximum seed germination response to temperature were assessed. Cumulative temperature response indices (CTRI) for pollen, seed, and physiological parameters were derived and used to classify cultivars for temperature tolerance. CTRI based on pollen parameters showed significant, but poor correlation with physiological parameters. CTRI based on seed parameters showed significant correlation with CTRI-physiological parameters. It is concluded that screening using pollen parameters will be ideal for reproductive temperature tolerance while seed and physiological parameters will be suitable for screening vegetative temperature tolerance. Identified tolerant cultivars are potential candidates for breeding programs to develop heat and cold tolerant ornamental pepper genotypes