Developmental physiology and ripening behaviour of 'Senorita' banana (Musa sp. L.) fruits

The 'Senorita' banana fruit exhibited a sigmoidal growth pattern. Growth was characterized by a slow then a rapid increase in size, volume, weight of fingers, pulp and peel weight during fruit development. A steady and/or declining rate of growth was observed between the 6th and 7th week from removal of male inflorescence. Respiration rate was high at the early stage of fruit development then decreased as the fruit matured. Ethylene gas production remained undetected during the entire period of fruit development. The amount of ethylene evolved was detected as the fruit began to ripen. Internal CO2 concentration was high at the time of male inflorescence removal and continued to decrease until the 4th week of development followed by a sharp rise on the 5th week then remained steady up to the 6th week. Thereafter, it declined. On the other hand, internal ethylene concentration was detected at a very low level on the 4th week then rose gradually until the 7th week. Total sugar content of the pulp remained low during development until the 4th week; during this period starch accumulated at a rapid rate. Thereafter, total sugar increased and starch content decreased. Soluble solids increased gradually as the fruit developed. This could be a consequence of sugar accumulation. Likewise, titratable acidity increased during fruit development. During ripening, fruits harvested at three stages of maturity (5, 6 and 7 weeks after male inflorescence removal) exhibited a climacteric pattern of respiration. The rise in respiration coincided with ethylene evolution. Ethylene production, which remained undetected at the earlier picking dates, increased suddenly during the course of ripening, then declined. The change from the unripe to the ripe stage was accompanied by decrease in starch content and increase in total sugars, total soluble solids and titratable acidity. Titratable acidity increased continually until CI 3 (more green than yellow) then decreased as the fruit turned yellow in color.