Plant & Food Research Case Study
RESEARCH & EVENTS
Plant & Food Research Case Study
Cultivar , rootstock combination critical for successful intensification of almonds
By Roberta De Bei , Grant Thorp , Nick Timbs , Wayne Kiley , Jill Stanley and Ken Breen
The Plant & Food Research trial has identified scion and rootstock combinations amenable to growing at higher density with minimal requirements for additional management . Dwarfing rootstocks and upright cultivars are the keys for the success of this highdensity almond orchard .
INTENSIFIED production systems have been shown to improve profitability and sustainability through increased yields and more efficient use of inputs in many horticultural crops . In almonds worldwide , an improved understanding of the crop physiology and the availability of new genetics for both cultivars and rootstocks are allowing the industry to explore higher density plantings , not only at an experimental scale , but increasingly also in commercial orchards . Here we present a case study that was established by The New Zealand Institute for Plant and Food Research Limited ( PFR ) in collaboration with Select Harvests at the Carina Farm in Robinvale and we invite everyone interested to join PFR and the Australian Almond Board ( ABA ) in collaboration with Select Harvests , for a trial walk on 4 December 2024 .
Aims and benefits of the work for
the industry The work aims to evaluate the performance of new almond rootstocks combined with traditional and new cultivars in a high-density orchard . Trees were planted in 2018 at 4.5 x 2m spacing ( 1111 trees / ha ). The trial examines the performance of the cultivars ; ‘ Carina ’, ‘ Nonpareil ’ and ‘ Vela ’ budded onto ‘ HBOK 27 ’ ( Controller™ 6 ( C6 )), ‘ HBOK 32 ’ ( Controller™ 7 ( C7 )) and ‘ HBOK 50 ’ ( Controller™ 9.5 ( C9.5 )) rootstocks . All trees were dormant-budded in March 2017 and grown for a full season in the nursery before planting into the field in winter 2018 as unpruned central-leader trees . Each year the tree growth ( height , width and trunk diameter ), yield , nut quality and water efficiency ( litres of water per kernel ) have been collected and analysed .
Trial results Early yields from this trial were impressive compared with known yields in lower density plantings , with significant crops harvested from second-leaf trees for ‘ Vela ’ and ‘ Carina ’ ( Figure 1 ). Yields from year to year fluctuated for all cultivar / rootstock combinations . Sixth leaf cumulative yields ( 2024 ) were higher in C9.5 for ‘ Carina ’, somewhat very similar in all three rootstocks for ‘ Nonpareil ’ while ‘ Vela ’ yielded best on C6 . Whilst yields on C9.5 were reasonably good overall , the trees were also bigger ( wider and taller canopies ) and they filled the space very quickly causing shading in the centre of the trees . These trees are now becoming difficult to manage at these row and tree spacings and a yield drop could be expected in the coming years as a result of shading . Significant pruning is needed to keep the trees within their required footprint . In contrast , the trees on C6 rootstock are compact and produce porous canopies , allowing good light penetration into the centre of the trees . These trees require minimal pruning , which would be a significant saving in costs as well as ensuring wood with fruiting potential remains .
Significance of the trial walk The field day at Select Harvests in Robinvale , to be held on Dec 4 th 2024 , will showcase a successful high-density demonstration plot , offering participants a practical example of effective scion-rootstock combinations . Participants can learn how different genotypes perform under similar conditions , providing insights into their suitability for highdensity systems . In addition , this will be an opportunity to network with the researchers who will share data and information collected from the trial , providing insights into tree water usage , the link between irrigation and canopy light
Figure 1 : Cumulative kernel yield ( 2020-2024 ) per hectare of ‘ Carina ’, ‘ Nonpareil ’, ‘ Vela ’ almond trees budded onto Controller™ 6 , Controller™ 7 and Controller™ 9.5 rootstocks at Carina Farm .
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Statistical analysis reported only for the final cumulative yield value ( 2024 ). Within cultivar , columns with different letters are different ( p < 0.05 ). In A Nutshell - Winter 2024 Vol 25 Issue 2