APS_JANUARY2024

E lderberry

19 20

Table 3. Mean root dry weight of elderberry plants after root pruning and transplanting into a 397 larger container. i 398 Root pruning treatment Transplanting treatment 399 Year NRP RP NT T 400 ---------------------------- Root dry weight (g) ---------------------------------- 401 2022 256 Ba 169 Bb 181 Bb 243 Ba 402 2023 269 Aa 187 Ab 191 Ab 264 Aa Table 3. Mean root dry weight of elderberry plants after root pruning and transplanting into a larger container. i

403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418

Root pruning

Transplanting treatment

treatment

NT

T

------ Root dry weight (g) ------

NRP

204 Ab 169 Bb

321 Aa 187 Ba

RP

Significance

Year (Y)

<0.001 <0.001 <0.001

Root pruning (RP)

Shift (S) Y x RP

0.003

Y x T

<0.001 <0.001

RP x T

Y x RP x T 419 i NRP = no root pruning, RP = root pruning, T = transplanting, NT = no transplanting. Means 420 within a column followed by the same uppercase letters and means within a row followed by 421 the same lowercase letters are not significantly different, P ≤ 0.05. Mean differences are based 422 on a one degree of freedom F-test. 423 i NRP = no root pruning, RP = root pruning, T = transplanting, NT = no transplanting. Means within a column followed by the same uppercase letters and means within a row followed by the same lowercase letters are not significantly different, P ≤ 0.05. Mean differences are based on a one degree of freedom F-test. 0.891

weight by 36.4% and 9.6%, respectively. Reproductive response to treatments. In 2022, all elderberry plants failed to produce flowers and fruit. However, plants in the RP + NT treatment were the only ones that did not bloom in 2023. Mean fruit number for the NRP + T treatment was the highest, that for the NRP + NT treatment was intermediate, and RP + T was the lowest, with similar results for fruit weight (Table 4). Discussion Results from this study demonstrated that RP + NT treatments resulted in the greatest reductions in shoot growth in both years. De spite the regeneration of roots after pruning,

this treatment, as well as the NT treatment re sulted in the least root growth in both years. However, transplanting elderberry plants into larger containers reduced the effect of root pruning, resulting in more shoot and root dry weight (Tables 2, 3). These results are consis tent with previous studies on perennial fruit crops grown in containers (Darnell et al. 2008) and in the field (Campbell et al. 2022; Ferree et al. 1999; Saure 2007; Schupp and Ferree 1988). Root pruning also affected fruiting in 2023 (Table 4). No fruit were harvested after RP + NT and fruit yield was minimal after RP + T. Even when roots were left unpruned, fruit yield was reduced by 38% when plants were