Comparative development, maturation and ripening of seedless and seed-containing bell pepper fruits

• Development and ripening of seed-containing and seedless pepper fruits are compared.
• Seedless fruit were smaller and growth ceased earlier than in seed-containing fruit.
• Seedless fruit respired faster throughout maturation and ripening.
• CO2 and ethylene concentrations within the fruit differed relative to maturation.
• The presence or absence of seeds affects fruit growth, maturation and ripening.

Bell pepper (Capsicum annuum L.) cv. Yolo Wonder was cultivated in a greenhouse during spring and summer and fruit set either by natural pollination (seed-containing) or by the application of 1-naphthaleneacetic acid (NAA) after emasculation (seedless, parthenocarpic fruit). The seedless fruit were significantly smaller in size and fresh weight than the seed-containing fruit. Moreover, seedless fruit attained their maximum volume and fresh weight at the mature green stage (G), whereas seed-containing fruit continued to increase in size and weight until red ripe (R). The seedless fruit were less green at stage G, but redder at stage R than the seed-containing fruit and had a higher rate of respiration throughout maturation and ripening. The metabolic activity of the seeds within the seed-containing fruit appeared to influence the composition of the atmosphere within the fruit cavity since at stages G and GR (breaker stage: 30–50% red, but seeds immature) the CO2 concentration was higher than in seedless fruit, whereas at stage R (when the seeds were mature) the CO2 concentration was the same in both types of fruit. The seeds also appeared to influence the ethylene concentration within the fruit cavity, which was higher in seed-containing fruit than in seedless fruit.