APS_October 2018

J ournal of the A merican P omological S ociety

228

however, better yields were achieved by re- moving fruit from late-fruiting cultivars such as ‘Elliott’ (Strik & Buller, 2005). In our tri- als, FB removal in early-fruiting cultivars ‘Star’ and ‘O’Neal’ during the first 2 years after planting (the T0 treatment) caused a re- duction in the cumulative fruit yield in com- parison with early cropping treatments.  Annual fruit yield progression showed that the presence of fruit during the first year (as in the T2 and T3 treatments) did not affect

fruit yield in year 2. In fact, both ‘Star’ and ‘O’Neal’ plants undergoing the T2 and T3 treatments produced the most fruit (Figure 3a, 3c). In contrast, fruit load during year 2 strongly affected fruit yield in year 3, with year 3 yields for both cultivars severely re- duced in T2 and T3 plants with high crop load treatments (Figure 3b, 3d). Year 2, T1 crop load seemed to be appropriate for ‘Star’ because relative fruit yields were only slight- ly lower than in year 3 T0 plants (– 8%) (Fig-

Star

b)

a)

1

100

100

T2

T0

T1

75

75

T3

50

50

T1

T3

25

25

T2

0 Relative fruit yield per plant (%) at year 2 1 T0

0 Relative fruit yield per plant (%) at year 3

0

35

70

105

140

0

5

9

14

Fruit number per plant at year 2

Fruit number per plant at year 1

O’Neal

c)

d)

100

100

T0

T2

T3

75

75

T1

T1

50

50

T2

25

25

T3

T0

0 Relative fruit yield per plant (%) at year 3

0 Relative fruti yield per plant (%) at year 2

0

20

40

60

0

8

17

25

Fruit number per plant at year 2

Fruit number per plant at year 1

Figure 3. Relationship between the number of fruits per plant and relative fruit yield the following year for ‘Star’ and ‘O’Neal’ Southern highbush blueberry cultivars subjected to different flower bud (FB) thinning treatments. Treatments included T0, control treatment, 100% FB removal during the first 2 years; T1, 100% and 50% FB removal at year 1 and year 2, respectively; T2, 50% and 0% FB removal at year 1 and year 2, respectively; T3, no FB removal during the first 2 years after planting. Figure 3. Relationship between the number of fruits per plant and relative fruit yield the following year for ‘Star’ and ‘O’Neal’ Southern highbush blueberry cultivars subjected to different flower bud (FB) thinning treatments. Treatments included T0, control treatment, 100% FB removal during the first 2 years; T1, 100% and 50% FB removal at year 1 and year 2, respectively; T2, 50% and 0% FB removal at year 1 and year 2, respectively; T3, no FB removal during the first 2 years after planting.