Lexie McClymont, Ian Goodwin, David Cornwall, Dave Haberfield, Wendy Sessions and Susanna Turpin
The team at the Horticulture Centre of Excellence share an update on the ‘Profitable Pear Systems’ project at Tatura looking at pear rootstocks for red-blushed pears.
Trees within the rootstock experiment at the Victorian Department of Economic Development, Jobs, Transport and Resources (DEDJTR), Tatura, are entering their third leaf this season. Initial results indicate significant differences between cultivars and rootstocks in terms of tree establishment and flowering.
Rootstock and cultivar selection is a major consideration in any production system but will be of particular importance in high density and trellis systems where precocity and sustained yields will be needed to recoup establishment costs. D6 is well known as a vigorous rootstock while Quince A has performed well with traditional scions in local demonstration sites, as reported in the article ‘Rootstocks for intensive pear production’ in Australian Fruitgrower (Nov 2014) .
However, tree performance is not entirely predictable based on rootstock alone, as scion can interact with rootstock. For example, in a pear rootstock trial in Israel, quince rootstocks were shown to perform well compared to Pyrus betulaefolia with regard to yield when grown with Spandon Estiva scions, but poorly when the scion was Corsica, Bartlett Sport or Beurre Superfin.
Additionally, location and tree management can influence rootstock effects on tree performance and potentially mitigate or enhance differences between rootstocks.
The influence of rootstock on the performance of three promising new pear selections from the Australian National Pear Breeding Program is being evaluated in the Pear Field Laboratory at the Department’s Tatura site. The primary aim of this experiment is to determine which rootstocks are most appropriate for use with each cultivar, based on tree growth, precocity and yield.
In this article we present preliminary results for the most vigorous (ANP-0131, which will be marketed as Deliza®) and least vigorous (ANP-0534) of the three cultivars.
As expected, D6 produced the most vigorous rootstock-scion combination, with leader height, leader diameter and pruning weights in the 2014-2015 season (second leaf) exceeding those of other treatments. There was no significant difference between Quince A and Quince C (with Beurre Hardy interstems) and BP1 rootstocks in terms of vegetative growth, although BP1 tended to be less vigorous.
This season (2015-2016), flower number (flower clusters per tree) and flowering intensity (flower clusters per metre of tree height) were significantly higher for ANP-0131 on Quince A-Beurre Hardy than for other rootstock-scion combinations.
Despite a large range in the number of flower clusters on ANP-0534, differences between rootstocks were not significant. This reflects variable flowering intensity in young trees. Although differences were not significant for ANP-0534, Quince C-Beurre Hardy was the most promising rootstock in terms of flower number and intensity.
Using a Nijisseiki interstem with D6 rootstock decreased vegetative growth in the initial seasons but did not affect cluster number or flowering intensity, compared to D6. It is known that Nijisseiki material is widely infected with virus in Australia. Comparison of the D6-Nijisseiki treatment with a D6-virus treatment (trees budded with infected material in 2014) will allow the effects of interstem and virus to be separated.
Fruit set, yield and fruit quality will be assessed later this season (2015-2016).
About the authors
Lexie McClymont, Ian Goodwin, David Cornwall, Dave Haberfield and Wendy Sessions are horticultural researchers at DEDJTR. Susanna Turpin is a private consultant for TDI Select Fruits, Tatura. For more information contact Lexie on 03 5833 5260 or Lexie.McClymont@ecodev.vic.gov.au.