Response of 'Apple' mango fruit to 1-methylcyclopropene as affected by agro-ecological zone and maturity stage

Preharvest production conditions affect fruit growth and development and subsequently their postharvest characteristics. In this study the response of 'Apple' mango fruits produced under two different agro-ecological zones (AEZs) in Kenya to 1-methylcycopropene (1-MCP) was evaluated. 1-MCP is an inhibitor of ethylene perception and action that is used to slow ripening and extend the shelf life of climacteric fruits such as mango. The mango fruits used in the study were harvested from a sub-humid AEZ (Embu) and a semi-arid AEZ (Makueni) at two stages of maturity. The maturity stages were defined by the flesh colour and respiratory activity as stage 1 (mature green) and stage 2 (advanced maturity). Homogenous fruit samples were treated with 1-MCP at 1 ppm for 24 h and thereafter stored at ambient room conditions (Temperature: 25 ± 1°C and RH: 60 ± 5%). Efficacy of 1-MCP was determined from ripening changes including respiratory activity, ethylene evolution, flesh/peel colour and firmness, titratable acidity (TTA) and total soluble solids (TSS) which were measured using standard protocols. The results showed that irrespective of AEZ and stage of maturity, 1-MCP treatment delayed ripening of the fruits, thereby slightly extending their shelf life by 2-3 days. The AEZ had significant (P≤0.05) effect on the fruit response to 1-MCP treatment, irrespective of stage of maturity. Fruits from the semi-arid AEZ (Makueni) were more responsive to 1-MCP treatment as evidenced by lower respiratory activity and slower progression of ripening changes including firmness, colour, TTA and TSS. Additionally better response to 1-MCP was observed in stage 1 fruits. It was concluded that AEZ and maturity stage have a significant effect on mango fruit response to 1-MCP and should be considered while designing postharvest treatment regimes.