Figures 1-5 relate to NZ Avocado R&D Officer Phillip West...

Handout, NZ Avocado field day, Heller’s orchard, Katikati, November 7.

Figures 1-5 relate to NZ Avocado R&D Officer Phillip West’s presentation.

Fig 1:

There are on-orchard variations in temperature – this potentially impacts pollination and fruit set. Plant & Food Research are looking into the effects of this on the timing of flower opening

Fig 2:

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Fig 3: Focus of this work was to measure quantify how pruning can correct the balance of a tree. From our trial we have observed that pruning did not have negative impact on yield

Fig 4:

Focus of this work was to quantify how pruning can correct the balance of a tree. From our trial we have observed that pruning did have a positive impact on fruit size.

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Fig 5:

Pruning in December encouraged vegetative flush which improved canopy density. A similar effect was seen from the February prune but trees had less time for the flucsh to develop before winter slowed the trees’ growth

Below: Matthew Heller and Dr Alvaro Vidiella - Discussion on the orchard’s characteristics and management

Table 1:

Date AvoMix kg/tree

Boron kg/tree Bortrac CAN gypsum lime

rapid lime

triple super zintrac

4/11/2013 1.5

29/11/2013 2.2

0.1 kg/tree

30/12/2013 2.2

0.1 kg/tree 1/02/2014 2.2 0.35

1/03/2014 2 0.35 3/04/2014 1.5

9/05/2014 1.5

1/06/2014 1.5

1 kg/tree

28/07/2014 1

1.5 kg/tree

29/07/2014

600 kg/ha

600 kg/ha

24/08/2014 1.5 0.5

2 kg/ha 22/09/2014 2

30/09/2014

3 l/ha

1 l/ha 19/10/2014 1.5

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Fig 6: Elevation and temp differences:

Fig 7: Yield

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Fig 8: Performance

Philip West:

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The next two documents are the Heller’s last leaf and soil analysis.

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Avocado tree water use and effects of water stress 7 November

- Dr Mike Clearwater, Waikato University

Irrigation requirements for avocado flowering and fruit development

Background: Many growers irrigate, but there are no clear guidelines as to how much, and when, to irrigate. Internationally there have been few attempts to directly quantify exactly how much water avocado trees require for optimum production. There is also a widespread understanding that irrigation during spring is important, because flowering causes stress to the tree that may be exacerbated by short term soil moisture deficits.

Goals: • Quantify avocado tree water use under New Zealand conditions throughout the year. Use this

information to develop recommendations and crop factors for irrigation scheduling. • Investigate the effects of spring soil water deficits on flowering and fruit set, so recommendations for

spring irrigation practice can be developed.

Methods: • Install meteorological station, soil moisture sensors and heat pulse sap flow gauges (Fig. 1) in three

mature (ca. 15 years) and three young (ca. 3 years) trees growing in an irrigated orchard. Monitor tree phenology, leaf area, flowering and crop load. Sap flow provides estimates of actual tree water use (Fig. 2), for comparison with potential evapotranspiration (ETo) estimated from the meteorological measurements. Tree water use relative to ETo (the ‘crop factor’) should vary with season and phonological stage. Once determined, crop factors can be used to estimate irrigation requirements in other orchards, using web based applications and standard meteorological data.

• Install rainout shelters (Fig. 3) around young fruiting trees so that we can impose a drought during flowering. Soil moisture, soil temperature, tree water potential, flowering behaviour and fruit set monitored to determine the effect of rain exclusion on the trees, flowering and fruit set. If we are successful in imposing a drought (measured as changes in tree pre-dawn water potential), we will examine the effects of this on flower retention, opening behaviour, fertilisation and fruit set.

Progress: Field measurements started in the past month. The meteorological station, soil moisture, soil temperature sensors, and rain out shelters have been installed in the block of young trees, and flower monitoring initiated. Sap flow gauges were installed in young and mature trees this week.

Acknowledgements: Collaboration between NZ Avocado, Plant & Food Research and University of Waikato, incorporating an MSc research project by Teruko Kaneko.

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Fig 1: Example of heat pulse sap flow gauges installed on a young avocado tree (left), and in a kiwifruit vine (right)

Fig 2: Example of the results obtained from sap flow measurements – direct measurements of tree water use

Fig 3: Rain-out shelters and meteorological station installed around young flowering avocado trees

0

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300 305 310 315 320

Tran

spira

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(L h

our-1

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Day of the year

tree 1tree 2

Tree 2 deflowered

Tree 1 deleafed

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Figures 1-5 relate to NZ Avocado R&D Officer Phillip West...

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