APS_Jan2023

A pple

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(2016-19) and 2019 TCA. All fruit were counted, and the total crop yield weighed for each tree in each year, and average fruit weight for 2019 and for 2016-19 were cal culated from total fruit weight harvested and number of fruit harvested per tree. Data were subjected to analysis of vari ance with the MIXED procedure of the SAS statistical analysis software (SAS Institute, Cary, NC). In the analyses, fixed main effects were rootstock and site. Block (within site) was a random, nested effect. In nearly all cas es, the interaction of rootstock and site was Table 2. At-planting characteristics (2015) of Modi® trees in the 2015 NC-140 Organic Apple Rootstock Trial. All data are least-squares means adjusted for missing subclasses. z Table 2. At-planting characteristics (2015) of Modi® trees in the 2015 NC-140 Organic Apple Rootstock Trial. ll data are least-squares means adjusted for is i s s. z

significant. Rootstock differences within site were assessed (for all sites individually and including all rootstocks, also by the MIXED procedure) for survival (through 2019), TCA (2019), cumulative yield per tree (2016-19), cumulative yield efficiency (2016-19), and average fruit weight (2016-19). Because not all sites included G.16 rootstock, analyses comparing rootstocks across all sites exclud ed that rootstock. However, G.16 was includ ed in comparisons of rootstocks within states in which it was included in the trial. Mean separations among rootstocks in all cases were performed by Tukey’s HSD (P = 0.05). Results Tree Characteristics at and Soon af ter Planting. TCA at planting varied by rootstock.Trees on G.202 and G.890 were the largest and those on G.222 were the smallest (Table 2). The number of branches remaining after the initial pruning also varied by rootstock. Trees on G.890 had the most branches, and those on G.222 had the fewest. Graft union height varied somewhat by root stock, with the highest unions for trees on G.222 and G.935 and the lowest for trees on M.9 NAKBT337 (Table 2). Among sites, there were no significant differences in TCA at planting, but coop erators left differing numbers of lateral branches after the initial pruning (Table 2). Nova Scotia left the largest number, and New Mexico, California, Michigan, New York (Ithaca), Vermont, and Massa chusetts had the fewest. Cooperators also differed in their approach to graft union height above the soil line after planting (Table 2). Graft unions were highest in New York (Ithaca), and lowest in Michi gan. Site Effects on Tree Performance. Over the 5 years of this trial, sites differed in all aspects of tree performance (Table 3). Among sites, survival was significantly lower in California (64%), than all other sites, and for the other nine locations, sur-

Branches at planting after initial pruning (no.)

Trunk cross sectional area at planting (cm 2 )

Graft union height (cm)

Rootstock G.11

1.4 c 1.2 ab 12.3 ab 1.2 d 0.8 bcd 11.2 bc 1.8 a 1.2 ab 12.4 ab 0.9 e 0.4 de 12.4 ab 1.6 b 1.1 b 12.6 ab

G.30 G.41

G.202 G.214 G.222 G.890 G.935 G.969

0.2 f 0.1 e 1.8 a 1.5 a

13.3 a 12.3 ab

1.7 b 0.9 bc 13.0 a 1.3 d 0.6 cde 11.3 bc 1.3 d 0.7 bcd 10.4 c

M.9 NAKBT337

Location CA

1.2 a 0.3 c 1.3 a --- 1.4 a 0.0 c 1.2 a 0.3 c 1.3 a 0.4 c 1.2 a 3.0 a 1.5 a 1.5 b 1.3 a 0.3 c 1.4 a 0.3 c --- 1.7 b

--- ---

CO

ID

11.2 de 10.7 de 12.3 cd 13.9 bc 14.9 ab 16.4 a 7.4 f

MA

MI

NM NS

NYG NYI

VT

z Values within a column for location or rootstock which share a letter do not differ at α=0.05 using Tukey's HSD adjustment for multiple comparisons. 10.2 e z Values within a column for location or rootstock which share a letter do not differ at α=0.05 using Tukey's HSD adjustment for multiple comparisons.