Fruit growth dynamics, respiration rate and physico-textural properties during pomegranate development and ripening

Abstract

The time course and pattern of fruit growth and changes in physical, physiological properties and texture dynamics of pomegranate fruit (cvs. ‘Bhagwa’ and ‘Ruby’) along the days after full bloom (DAFB) were studied over two different year seasons. Significant variations in fruit growth, respiration rate and physico-textural properties of the fruit were found at five maturity stages (S1–S5). Fruit lineal dimensions (length and diameter) exhibited a linear growth pattern and the fruit weight followed a similar pattern. Both fruit cultivars showed a decline in respiration rate during fruit development, with the highest respiration rate measured in immature fruits (‘Bhagwa’, 66.83mLCO2kg−1h−1; ‘Ruby’, 51.17mLCO2kg−1h−1) and declining with maturity to minimum rates in fully ripe fruit (stage 5) (S5) (‘Bhagwa’, 23.84mLCO2kg−1h−1; ‘Ruby’, 19.16mLCO2kg−1h−1). No ethylene gas was detected throughout fruit development. Fruit pigmentation increased with advancing maturity and the lowest total colour difference (TCD) between fruit peel and arils was noted in immature fruit. Textural dynamics of aril revealed increasing trend in bioyield force and elasticity with advancing maturity. Overall, the study indicated that fruit reached mature stage between the 132–139 DAFB for ‘Ruby’ and 140–165 DAFB for ‘Bhagwa’. This period could be regarded as the physiological mature stage of the fruits that would present the optimum values of harvesting properties desirable in the investigated cultivars. This information could be used as a tool to assist growers in assessing fruit readiness for harvest.