204 Levinsson: Post-transplant Shoot Growth is Affected by Site and Species transplant year, for either of the species. There was no interaction between production methods and sites during any of the post- transplant years for either of the species, showing that the site did not affect the production methods annual shoot growth capacity. while all Alnarp sweet cherry trees except the BR and AP trees had restored pre-transplant shoot growth (Figure 1). In 2011, the FC trees still had higher shoot growth than the BR, but were no longer separated from the AP trees. In Malmö, shoot growth with all production methods was still significantly lower than that of the undisturbed trees growth in 2007. The sweet cherry trees at Alnarp 2011 again showed significantly lower shoot growth than the undisturbed 2007’s trees (Figure 1). Shoot growth was, however, higher than in 2008 and 2009 for all production methods at both sites (Figure 1). Annual Red Oak Shoot Growth The undisturbed B&B and BR red oaks showed significantly higher shoot growth than trees produced with all the other meth- ods in the nurseries in 2007 (P < 0.0001). RP red oaks showed significantly lower shoot growth than B&B and BR trees, but exhibited significantly better growth than AP and FC trees (Table 1). The shoot growth for the red oaks grown with all meth- Figure 1. Annual shoot growth (mean ± SE) of sweet cherry and red oak during the nursery year of 2007 and during the four con- secutive post-transplant years, produced as: ● – BR (bare-rooted), ▲ – B&B (balled and burlapped), ■ – RP (root pruned), + – AP (air-potted), S – FC (fabric container) trees. The data points of BR and B&B in 2007 show the shoot growth from undisturbed trees in the fields, while the other data points in 2007 represents trees subjected to root pruning or transplanting treatments. Each data point in Malmö is the mean of four trees’ shoot growth and each data point in Alnarp is the mean of six trees’ shoot growth. The mean value of each tree was calculated from 16 shoots. Annual Sweet Cherry Shoot Growth During the pre-transplant nursery year, 2007, the undisturbed B&B and BR sweet cherry trees showed significantly higher shoot growth than the RP and FC trees (P < 0.0001). The AP trees showed shoot growth simi- lar to that of the undisturbed sweet cherry trees, despite being lifted and installed in a new production system (Table 1). As Table 1 also shows, there were significant differ- ences between the production methods during the two first post-transplant years. However, the sweet cherry trees pro- duced with all methods had very low shoot growth com- pared to the shoot growth of 2007’s undisturbed sweet cherry trees and no production method had regained nursery shoot growth rates during these years (Figure 1). After the shoot growth season of 2010, both sites showed higher shoot growth rates compared to the post-transplant shoot growth from the previous years. FC trees had signifi- cantly higher shoot growth than AP and BR, with both sites included in the analysis (P = 0.001). None of the Malmö planted sweet cherry trees had returned to nursery shoot growth rates, ©2013 International Society of Arboriculture ods was very low after shoot growth cessation in 2008 com- pared to the shoot growth of the undisturbed field-grown red oaks in 2007 (Figure 1). Significant differences were however seen between the production methods (P < 0.0001) with B&B trees showing higher shoot growth than BR, FC, and RP trees. During the last three years, shoot growth was only a small fraction of that of the undisturbed red oaks in 2007 (Figure 1). There were however annual differences between the production methods in both 2009 and 2010, with AP trees showing a higher shoot growth than RP trees in each. The red oaks at Alnarp showed slightly greater shoot growth in 2011 than 2010, but growth was still far lower than that of the undisturbed field-grown trees in 2007 (Figure 1). Accumulated Shoot Growth of Both Species In order to estimate the impact of the production method on the size of the crown four years after transplanting and on the total shoot growth during the period of the study, the accumulated shoot growth was calculated with and without the nursery year (Table 2). The shoot growth of sweet cherry trees in Malmö varied with the production method when the nursery year was included in the analysis (P = 0.029). AP and B&B sweet cherry trees showed significantly higher shoot growth than RP trees (P = 0.025). This difference was not significant when the data from the nursery growth rates of 2007 were excluded, showing that post-transplant growth rates did not differ between the production methods. This shows that the shoot growth in the nursery still had a significant impact on the accumulated shoot growth determined four years after the transplanting of this species at the urban planting site. For the red oaks, differences in accumulated shoot growth were seen among the trees produced with the different meth- ods at both sites when all years were included in the analysis. Red oaks that were not disturbed until transplanting (B&B and BR) still showed significantly higher accumulated growth four years after transplanting than the red oaks that had been pro- duced using other methods in 2007 (P < 0.0001 at both sites). Excluding the year in the nursery also showed differences in accumulated shoot growth between the production meth- ods (Table 2). RP red oaks showed the lowest accumulated growth at both sites. However, the method producing red oaks
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