PREHARVEST FACTORS INFLUENCING 'HASS' AVOCADO (PERSEA AMERICANA MILL.) QUALITY DURING LONG TERM STORAGE

Avocado quality variability is due to the broad range of conditions in which trees are grown, especially in terms of climate and soil, and also associated with different cultural practices used among avocado growers. In the last four years, we have been performing a project in order to understand this variability by determining the effect of preharvest factors (climate, nutrition, cultural management, etc.) on the postharvest life of ‘Hass’ avocados, shipped under regular air (RA) and controlled atmosphere (CA) conditions. Fruit was collected from 11 commercial orchards during the 2009/10, 2010/11 and 2011/12 seasons, stored under RA and CA (4%O₂ and 6% CO₂) for 40 and 55 days at 5°C and 90% RH, and ripened at 20°C after cold storage until reaching the ready to eat stage. The postharvest parameters evaluated included flesh firmness, color, physiological disorders and days to reach ripening. A multivariate analysis was performed to determine a possible relationship between preharvest factors and postharvest avocado quality. Under both storage conditions, a high fruit variability among experimental sites was observed in the different quality attributes evaluated after storage. Among the variables studied, the days between flowering and harvest had an inverse effect on fruit firmness level after storage. A similar behavior was found for N/Ca ratio and oil content at harvest. Other factors that directly affected fruit firmness were calcium content at harvest and orchard elevation.