Selection of sweet pepper (Capsicum annuum L.) genotypes for parthenocarpic fruit growth

Yield irregularity and blossom-end-rot are major problems in sweet pepper production, which can be reduced by parthenocarpy. However no commercial parthenocarpic cultivars are available. The purpose of this study was to find parthenocarpic genotype(s) of sweet pepper with the ability to produce good quality fruits without seeds. Eleven genotypes of sweet pepper were studied at normal (20/20°C D/N) and at low night temperature (20/10°C D/N), in two greenhouse compartments from January till May. Fruit length, diameter, fresh and dry weight and number of seeds per fruit were measured. A higher percentage of parthenocarpic fruits was observed for all genotypes at low night temperature compared to normal temperature. Within the genotypes which showed at least 60% parthencarpic fruit growth at low night temperature, two groups were distinguished, which showed a different expression of parthenocarpy in response to the environment. In one set of genotypes (Line 1 and Line 3) high expressivity for parthenocarpy was found irrespective of night temperature. In another set of genotypes (Gen A, Gen B, Gen C, Lamuyo A, Lamuyo B and Bruinsma Wonder), a high level of parthenocarpy was expressed at low night temperature only, which may be due to non-viable pollen at low night temperature. Further evaluation of the latter six genotypes resulted in one genotype (Bruinsma Wonder) for which the absence of seeds only marginally influenced shape and size of fruits. These selected genotypes may eventually lead to an exploitation of parthenocarpy in sweet pepper breeding.