Pre-harvest factors influencing “Hass” avocado quality during long term storageBruno Defilippi1, Paula Robledo1, Raúl Ferreyra1, Sylvana Soto1 and Jorge Saavedra2

1Instituto de Investigaciones Agropecuarias, CRI-La Platina, Unidad de Postcosecha. Santiago-Chile 2Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile

Email: bdefilip@inia.cl

Chile is an important avocado supplier in the world exporting a 60% of its production, mainly to USA, followed by Europe. Most of this volume reaches the market in controlled atmosphere containers; however, still a major challenge for the Chilean industry is to provide a homogenous fruit in terms of quality, especially considering that an important variability could be found in maturity stages of the fruit within a box or a pallet. Part of this 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 pre-harvest factors on the postharvest life of avocados cv. Hass, shipped under regular air (RA) and controlled atmosphere (CA, 4% O2 and 6% O2) conditions. 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. Experimental approach

Color Scale

1 2 3 4 5

Preharvest factors

RA storage at 5°C

Shelf-life at 20 °C

Harvest (9-10% oil content)

Results

Histograma para Cosecha

0 10 20 30 40 50 60 70 80Cosecha

0

4

8

12

16

20

frec

uenc

ia

DistribuciónNormal

At harvest

Freq

uenc

y

Firmness (lb-f)

Histograma para 35

0 10 20 30 40 50 60 70 8035

0

4

8

12

16

20

24

28

frec

uenc

ia

DistribuciónNormal

35 days at 5 °C (RA)

Freq

uenc

y

Firmness(lb-f)

soft firm soft firm

40 days at 5°C

Grower Firmness (lb-f) External colorRA CA* RA CA

Los Andes 7.6 55.4 1.8 1Panquehue 30.6 55.1 1 1Llay llay 28 56.5 1 1Hijuelas 19.7 64.3 2.7 1Chincolco 39.2 53.5 1.2 1Jaururo 8.9 58.8 3 1Romeral 7.7 61.5 3.3 1Ocoa 32.3 64.8 2 1San Felipe 38.3 66 1.6 1Melipilla 9.7 61.6 1.6 1S. Domingo 26 52.3 2.8 1Cabildo 13.6 62.2 2.8 1

55 days at 5°C

Grower Firmness (lb-f) External colorRA CA* RA CA

Los Andes 4.8 39.6 3.4 1.4Panquehue 18.9 55.6 2.5 1Llay llay 19.4 54.2 2.2 1Hijuelas 26.5 48.4 2.5 1Chincolco 24.5 56.5 2.5 1Jaururo 3.8 47.2 3.1 2.2Romeral 6.9 63.2 3.7 1.4Ocoa 12.2 49.5 2.6 1.6San Felipe 18.3 48.2 2.2 1.6Melipilla 4.4 56.6 2.9 1S. Domingo 13.5 45.3 3.2 1.2Cabildo 4.6 42.2 3.1 1.2

Final remarks

CA storage at 5°C Days to ready to eat stage (< 2 Lbf)

*CA storage = 30 days CA + 10 days RA storage *CA storage = 30 days CA + 25 days RA storage

1. The use of CA on avocado showed several benefits in terms of fruit quality, compared to RA storage, including a delay in pulp softening and retention in color development. However, there were important differences in the efficacy of both treatments among growers.

2. Why do we have these differences in efficacy?. In the first 3 seasons, we characterized and identified the main factors determining the variability in postharvest storage potential of 46 growers under RA storage. For firmness and color development there was a high variability for both parameters after 35 d. of storage, with fruit on a ready to eat stage at the end of storage for some growers (<2 lb-f or black color), while others still with a firm fruit (> 50 lb-f and green).

The most important factors determining firmness were: time between flowering and harvest (diascosech), calcium content in the fruit at harvest (TFCa), orchard height (Altitud), nitrogen/calcium ratio in the flesh at harvest (N/Ca), fruit dry matter (MSeca0), and all of them located far from the center of the PLS model (R2Y = 80.3% ; Q2 =66.7%).

3. What factors are affecting postharvest?

A high fruit variability among growers was observed in the quality parameters studied after long term storage. Apart from the benefits already mentioned, the use of CA reduced this variability.

Among the factors studied, days between flowering and harvest had an inverse effect on fruit firmness level. Other factors with a similar behavior were ratio N/Ca at harvest and dry matter content.

Presently, we are working in the following approach in order to elucidate the underlying mechanism determining postharvest performance of avocado under CA storage.

N Growth of new leaves in spring

Irrigation in Spring: excess or

deficit

Cell wallPhotosynthesis

Postharvest life

Leaf area index

PAR radiationinterception

Fruit age NFruit drymatter

Tree age

Climate

Average annualminimun temperature

Altitude of the orchard

Anual temperaturerange

Average annualtemperature

Calciumin pulp

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