RESEARCH UPDATE
Figure 4 . Yield of Shasta and Vela as influenced by density and rootstock in 2021 / 22 . Planted 2019 / 20 as small potted trees (< 6mm trunk ).
supporting , the trellis structure will be removed and repurposed at the end of the 2023 season . Other experimental / demonstration high density almond orchards have been established without the use of trellis ( e . g . Agriculture Victoria , Agromillora and PFR plantings ). The SARDI trial is now in its fourth leaf and all of the variety by rootstock combinations that were planted at 1.5 m spacings ( 1481 trees / ha ) look balanced , having filled their space with small diameter branches . Light is penetrating through the canopy and the crop load appears to be keeping the development of vigorous watershoots in check . At the lower densities , the suitability of differing growth habits is becoming apparent . Shasta trees , planted at both 2.5 m ( 889 trees / ha ) and 3.5 m ( 635 trees / ha ), have been slower to fill the available space than Vela due to the variety ’ s upright growth habit with fewer lateral branches . The unproductive areas between trees may fill with time , but this appears to be a lost opportunity for an orchard design focussed on early and sustained yields . The Shasta variety also tends to spur at the end of its long shoots , and these then lay over with the weight of nuts . Nut laden shoots that lean into the row are susceptible to removal during late spring hedging operations . Vela is less susceptible to this risk and is also more efficient at spreading lateral shoots that can increase the canopy density in the space between trees .
Yield response One of the earliest learnings from this orchard has been the value of planting advanced nursery stock . Whilst the health of the planting material received for this trial was exceptional , nursery trees were delivered as very small potted plants . Given their small size , much of the first two seasons was spent developing the canopy , which limited the opportunity for high early yields . Commercially harvestable yields were finally achieved in 2021 / 22 , three years after planting ( Figure 4 ). Had the planting material been more advanced , such as traditional unheaded field grown nursery trees , the yields presented in Figure 4 may have been achieved in the second season . The value of advanced planting material is well described in the PFR factsheet series , ‘ Almond planting and early tree establishment ’. In 2021 / 22 , trees grafted to the Rootpac-40 and Controller-6 rootstocks outperformed those grafted to Controller-7 . Within each variety by rootstock
Figure
5 . Postharvest assessment of density and genotype effects on kernel quality metrics .
combination , trees planted at 1481 trees / ha outperformed those at the lower densities . Kernel size averaged more than 1.2 g for Shasta and 1.6 g for Vela with Shasta showing signs of pinched tips and minor pepper spotting , both common for the region at the time . There was no interaction between kernel quality and the density by genotype treatments in this season . The poor yields from trees grafted to Controller-7 were likely a consequence of the rootstock ’ s susceptibility to alkaline soils ( a feature at one end of the trial orchard ). While trees grafted to this rootstock are clearly the least productive combination being tested , they have shown signs of improved growth in season 2023 .
Demonstration opportunity SARDI assessments will continue through the coming seasons and will ultimately contribute to production recommendations and cost benefit analysis . If you are interested in visiting this demonstration trial or any of SARDI ’ s other trials at the ACE experimental orchard , please contact SARDI on 08 8595 9100 or the ABA on 08 8584 7053 .
industry . australianalmonds . com . au
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