Research relating to avocado water use and water stress:
Fig. 1 New Zealand 1997-98 Summer Days of Soil Moisture Deficit.
TRIAL: MBIE - Irrigation - To determine water consumption of avocado orchards in NZ conditions - To evaluate the effect of different management irrigation strategies on productivity - To develop irrigation management tools that can be used by growers
Fig. 3 Trial trees with rainout shelters Fig. 4 The surface (0-12 cm) water contents of C2 and D2 on 19 December 2014 (after heavy rain). The soil close to D2 was drier, but water contents as the edges of the rainout shelters were high, suggesting water is moving into the root zone of drought treatment plants.
Fig. 2 New Zealand Median Summer Days of Soil Moisture Deficit.
Fig. 5 Soil moisture content of the control and drought treatments (n=5), at the depth of 0-20 cm, recorded using ECH2O probes. The rainout shelters were put from November 2014 to April 2015.
Figure 6. Fruit retention rates of the control and drought treatments (control n=761, drought n=1024). Significant fruit drop occurred during the early fruit development until February, and in July due to frost attack.
Fig. 7 Growth in fruit volume recording non-destructively from 2 diameters and 1 length (n=150). At harvest on 1st November, control had the average fruit weight of 276.2 (SD ± 51) g, while the drought treatment had only 217 (SD ± 42) g.
Data collected from rainout shelter trial trees Treatment
Plant no.
Fruit count
Fruit weight (g)
C1 C2 C3 C4 C5
202 187 76 163 47
253.9 ± 6.8 264.9 ± 7.6 289.3 ± 9.5 277.9 ± 8.9 294.1 ± 11.8
51.3 ± 1.4 49.5 ± 1.4 22.0 ± 0.7 45.3 ± 1.5 13.8 ± 0.6
29.2 ± 0.8 30.4 ± 0.5 31.7 ± 0.3 29.6 ± 0.8 31.0 ± 0.3
average
135
276.0 ± 7.5
36.4 ± 1.1
30.4 ± 0.3
D1 D2 D3 D4 D5
168 43 179 82 174
191.5 ± 6.2 214.0 ± 7.0 211.3 ± 8.7 242.7 ± 7.2 229.6 ± 9.2
32.2 ± 1.0 9.2 ± 0.3 37.8 ± 1.6 19.9 ± 0.6 39.9 ± 1.6
26.3 ± 0.5 28.3 ± 0.6 25.2 ± 0.8 28.9 ± 0.7 32.6 ± 0.7
average
129
217.8 ± 8.7
27.8 ± 1.0
28.3 ± 0.5
Control
Drought
Average fruit weight smaller in droughted trees
Trial will be repeated
Yield (kg)
Dry matter content (%)
Fruit sizes for irrigated (I) and non-irrigated (N) orchards
Fig. 8 Two non-irrigated orchards and one irrigated orchard have had data on fruit size collected. In some years the fruit size is larger in the irrigated orchards, and in some years there is no difference.
Fig. 7 Measuring daily water use using stem probes
Fig. 9 Daily water use by mature and young trees, measured by the sap flow technique, from November 2014 to October 2015. Reference ETo was obtained at the study site in Katikati.
Average daily evapotranspiration 2014
This will be repeated
August
September
October
1.4mm
1.9mm
2.9mm
TRIAL: MBIE - Pruning to balance trees
Yield - September
(No prune)
Fruit drop
Fruit size
(Dec) (Feb)
Heavy fruit set and no moisture means something
Treatment
Average Fruit Weight (g)
Average Fruit Size Class
Early summer prune
224.7a
25.2a
Late summer prune
227.8a
24.8a
Control
217.1b
26.0b
New Cultivar Trials: Trunk Diameter: The average trunk diameter of Maluma trees has been smaller than that of Hass trees in many of the trial orchards. This is in line with overseas reports which suggest Maluma has less vigour than Hass, and may be better suited for high-density plantings.
120 100 80
Hass
60
Maluma
40 20 0 Autumn Autumn Autumn Autumn Autumn Autumn 2010
2011
2012
2013
2014
Average trunk diameter (mm)
Trunk Diameter by Scion (Dusa Rootstock)
140
140 120 100 80 60 40 20 0
2015
Hass Maluma Autumn
Autumn
Autumn
2013
2014
2015
Baileys
Mangawhai
Flush Activity:
Flush Activity by Scion (Dusa Rootstock)
Carmen trees had a greater average flush intensity in Spring and lesser average flush intensity in Autumn than Hass trees at Baileys orchard. Similar trends were seen at other trial orchards. This may be due to heavier Autumn flowering and fuit-set experienced by Carmen trees. This suggest s that the phenology of Carmen trees may be on a different time-frame to that of Hass.
4 3.5
3 2.5
Carmen
2
Hass
1.5
Maluma
1 Autumn
Spring 2015
Baileys
Fruit Size:
Fruit Weight by Scion (Dusa Rootstock)
Yield by Scion (Dusa Rootstock)
350
50
300 250 200
Hass
150
Maluma
100 50 0 2014
2015 Mangawhai
Average Yield (kg/tree)
Average Fruit Weight (g)
Average trunk diameter (mm)
Trunk Diameter by Scion (Dusa Rootstock)
40 Hass
30
Maluma
20 10
0 2014
2015 Mangawhai
Maluma trees on average produced larger fruit (more than 50g larger) in 2014 and 2015 at the Mangawhai trial orchard. Some fruit were very large— up to 500g. The fruit also appeared more elongated, with a more pronounced neck.
Fruit Size:
Fruit Weight by Rootstock (Maluma Scion)
350
350
300
300
250 Bounty
200
Duke 7
150
Dusa
100
Zutano
50
Average Fruit Weight (g)
Average Fruit Weight (g)
Fruit Weight by Rootstock (Hass Scion)
250 200
Duke 7
150
Dusa
100
Zutano
50 0
0 2014
2014
2015
2015 Mangawhai
Mangawhai
The average fruit weight of Hass trees on Bounty and Dusa rootstock was greater than those on Duke 7 and Zutano rootstock in both 2014 and 2015 at the Mangawhai trial orchard. The same trend was seen for Maluma trees on Dusa rootstock compared to Duke 7 and Zutano (There are no Maluma on Bounty rootstock at this orchard).
Yield:
Flower Intensity by Rootstock (Hass Scion)
Yield by Rootstock (Hass Scion) 7
Average Yield (kg/tree)
50
6
40 Bounty
30
Duke 7
20 10 0 2014
2015
5
Bounty
4
Duke 7
3
Dusa
Dusa
2
Zutano
1
Zutano
0 2014
Mangawhai
2015
Mangawhai
The yield of Hass trees on Bounty and Dusa rootstock was greater than those on Duke 7 and Zutano rootstock in 2014 at the Mangawhai trial orchard. This year there was no significant difference, however the Bounty and Dusa trees experienced a greater flower intensity this year.
More detailed and extensive information on all five new cultivar trials, and data collected at these is now available on the website under: NZ Avocado industry website > Orchard Mngt > New cultivars http://industry.nzavocado.co.nz/industry/new_cultivars.csn
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