Bioenergetics, maintenance respiration and transpiration of pepper fruits

Structure and function of chile pepper Capsicum annuum var. annuum L. fruit tissues were examined by SEM, GC and porometry. Stomata were absent from the inner (endocarp) and outer (exocarp) epidermis of mature chile pepper fruits of cvs. Serrano, Jalapeno, Hungarian Wax, Anaheim and MexiBell. Fruit transpiration of 0.4 to 2.4 mmol H2O m(-2) s(-1) was hence attributed solely to cuticular transpiration. Chlorophyll contents of mature fruits ranged from 4.1 mu g/g to 76 mu g/g fresh weight with chlorophyll a:b ratios of 1.68:1 to 2.35:1. Locular space volumes and CO2 concentrations ranged respectively from 22% to 52% (v/v) and from 0.6 to 2.1% CO2 with concomitant locular oxygen concentrations from 18.4 to 20.6% O-2 and RQ of between 0.89 to 1.81. Immature seeds and placenta were the primary sources of accumulated CO2, while respiration of the endocarp was comparatively low. The large maintenance respiration from 0.81 to 2 mg CO2 [g dwt day](-1) and 0.54 to 1.3 mg glucose [g dwt day](-1) provided 0.05 to 1.3 kJoule fruit(-1) h(-1) for biochemical conversions.