Responses of apple fruit size to tree water status and crop load

Apple fruit size is influenced by position on the spur, and location and number of competing fruits. King fruit appear to have the greatest potential to size and grow best in the absence of intraspur fruit competition (ISFC). Accel (A) and NAA (N), commercial thinning chemicals, influence fruit size beyond their effects on crop load. A 2-year study was conducted to determine the effect of ISFC and position (king, K, or lateral, L) on fruit growth in response to A and N. Branches from `Redchief Delicious' were thinned, after petal fall, to one K, one L, one K + one L, or two L fruits per spur. Whole-tree treatments of N (15 mg·liter–1), A (50 mg·liter–1, 1993; 25 mg·liter–1), and a combination (N+A) were applied at 10-mm king fruit diameter. A nontreated control was included. In 1993, N and N+A reduced fruit size only with ISFC, while A increased fruit size in the absence of ISFC. In 1994, A had no effect, but N and N+A reduced fruit growth with ISFC. In both seasons, A and N decreased the frequency of spurs bearing multiple fruit, while N+A dramatically increased number of spurs with multiple fruits (branch survey).

Download Full-text

683 Contributions of Early Season Environment and Crop Load to Apple Fruit Development

HortScience ◽

10.21273/hortsci.35.3.516d ◽

2000 ◽

Vol 35 (3) ◽

pp. 516D-516

Author(s):

C.J. Stanley ◽

D.S. Tustin

Keyword(s):

Cell Division ◽

Fruit Size ◽

Cell Number ◽

Apple Fruit ◽

Fruit Weight ◽

Full Bloom ◽

Crop Load ◽

Early Season ◽

Growth Partitioning ◽

Load Conditions

Many factors contribute to final apple fruit size. Researchers have studied these factors and have developed models, some very complex. Results from many New Zealand regions over several years suggest that early season temperature along with crop load are the key factors driving final fruit size. Accumulated growing degree days from full bloom to 50 days after full bloom (DAFB), accounted for 90% of the variance in fruit weight of `Royal Gala' apples at 50 DAFB under nonlimiting low-crop-load conditions. In turn, fruit weight at 50 DAFB accounted for 90% of the variance in final fruit size at harvest under the low-crop-load conditions. We hypothesise that a potential maximum fruit size is set by 50 DAFB, determined by total fruit cell number, resulting from a temperature-responsive cell division phase. Under conditions of no limitations after the cell division phase, we suggest that all cells would expand to their optimum size to provide the maximum fruit size achievable for that cell number. Factors which affect growth partitioning among fruits, e.g., higher crop loads, would reduce final fruit size, for any given cell number, when grown in the same environment. In Oct. 1999, four different crop loads were established at full bloom on `Royal Gala' trees (M9 rootstock) in four climatically different regions. In Hawkes Bay, similar crop loads were established at 50 DAFB on additional trees. Hourly temperatures were recorded over the season. Fruit size was measured at 50 DAFB and fruit will be harvested in Feb. 2000. These data should provide fresh insight and discussion into the respective roles of temperature and competition during the cell division fruit growth phase on apple fruit size.

Download Full-text

166 Influence of Crop Level on Growth and Quality of `Braeburn' Apple Fruit

HortScience ◽

10.21273/hortsci.35.3.418e ◽

2000 ◽

Vol 35 (3) ◽

pp. 418E-419

Author(s):

P.I. Garriz ◽

G.M. Colavita ◽

H.L. Alvarez

Keyword(s):

Fruit Size ◽

Growing Season ◽

Apple Fruit ◽

Full Bloom ◽

Cross Sectional ◽

Crop Load ◽

Commercial Crop ◽

Source Sink ◽

Fruit Diameter

Crop load and the genetic biological carrying capacity (source–sink relationships) determine the potential for fruit size development on apple; however, the environment within which the fruit grows attenuates this potential. The effects of different crop loads on the growth pattern and the progress of maturity in apples were evaluated at the Comahue National Univ., Argentina (lat. 38 56'S long 67 59'W), during the 1998–99 growing season. Our experiment was conducted on 6-year-old `Braeburn'/Malling Merton 111 apple (Malus domestica Borkh.) trees spaced 4.0 × 2.3 m and trained to palmette leader. Treatments were 1) light crop load (LC), 2.5 fruit/cm2 trunk cross-sectional area (TCSA), 2) moderate crop load (MC), 6.5 fruit/cm2 TCSA (standard commercial crop load) and 3) high crop load (HC), minimum 8 fruit/cm2 TCSA, no fruit removed from tree. Whole trees were hand-thinned 19 days after full bloom (DAFB). Fruit diameter (FD) was taken at two weekly intervals (n = 24 per date and treatment) and maturity indexes were determined at harvest. Analysis of variance was used and mean separations were computed with Student's t test. From 38 DAFB until harvest, fruit size was significantly reduced (P < 0.01) in the HC trees, indicating that they were source-limited during growth. At 166 DAFB, FD was 7.48, 7.14, and 6.89 cm for the LC, MC and HC treatments, respectively. Adequate carbon was apparently available to support a commercial crop load since no differences were found between LC and MC trees. Crop level influenced flesh firmness; at 173 DAFB, it was significantly lower in HC trees than MC and LC trees (84.33, 92.51, and 91.57 N, respectively). These results suggest some goals of thinning for ensuring sizable `Braeburn' fruit.

Download Full-text

Rootstock Effects on Growth and Quality of `Gala' Apples

HortScience ◽

10.21273/hortsci.39.6.1231 ◽

2004 ◽

Vol 39 (6) ◽

pp. 1231-1233 ◽

Cited By ~ 14

Author(s):

Yahya K. Al-Hinai ◽

Teryl R. Roper

Keyword(s):

Agricultural Research ◽

Fruit Size ◽

Apple Fruit ◽

Fruit Weight ◽

Research Station ◽

Final Size ◽

Crop Load ◽

Yield Efficiency ◽

Load Effects

The effect of rootstock on apple size is not clear due to inconsistent results of published studies. This study was conducted over 3 years at the Peninsular Agricultural Research Station near Sturgeon Bay, WI on 6-year-old `Gala' apple trees (Malus domestica Borkh) grafted on Malling 26 (M.26), Ottawa 3, M.9 Pajam 1, and Vineland (V)-605 rootstocks. Fruit diameter was measured weekly. Fruit weight and volume were estimated by a quadratic regression of weekly measurements. Fruit weight was positively correlated with fruit volume. Rootstock had no effect on fruit growth and final size even with the removal of crop load effects. Crop load was a highly significant covariate for fruit size, but canopy light interception and seed count were not. Trees on M.26 EMLA had slightly higher yield in 2000 but rootstock did not affect yield efficiency any year. Rootstock had no influence on fruit quality attributes during 2001; however, in 2002, fruit obtained from trees on Pajam-1 tended to be less firm. Generally, apple fruit size was influenced by crop load and other factors, but not by rootstock.

Download Full-text

EFFECTS OF ROOTSTOCK ON `DELICIOUS' APPLE FRUIT PROPERTIES

HortScience ◽

10.21273/hortsci.25.9.1147a ◽

1990 ◽

Vol 25 (9) ◽

pp. 1147a-1147

Author(s):

Wesley R. Autio

Keyword(s):

Mineral Composition ◽

Fruit Size ◽

Apple Fruit ◽

Analysis Of Covariance ◽

Crop Load ◽

Fruit Maturity

The effects of rootstock on `Delicious' apple maturity, quality, size, mineral composition, and storability were studied over a 4-year period. Removing the effects of crop load and crop load within year by analysis of covariance produced results suggesting that M.27 EMLA and Ott.3 advanced fruit maturity and that M.7 EMLA delayed fruit maturity. M.9, MAC 9, OAR 1, M.9 EMLA, and M.26 EMLA either were inconsistent in their effect on maturity or consistently resulted in an intermediate maturity. Size, after adjusting for the effects of crop load and crop load within year, was consistently high for fruit from trees on M.9 EMLA, and lowest for fruit from trees on OAR 1. After adjusting for fruit size, fruit from trees on MAC 9 generally had high Ca contents, and fruit from trees on OAR 1 had low Ca contents. The effect of rootstock on storability appeared to be secondary and related to maturity and Ca level.

Download Full-text

682 New Perspectives on the Influence of Mid-season Environment on Apple Fruit Characteristics

HortScience ◽

10.21273/hortsci.35.3.516c ◽

2000 ◽

Vol 35 (3) ◽

pp. 516C-516

Author(s):

D.S. Tustin ◽

T. Fulton ◽

H. Brown

Keyword(s):

Cell Division ◽

Fruit Development ◽

Climatic Variability ◽

Fruit Size ◽

Cortical Cell ◽

Dry Weight ◽

Apple Fruit ◽

Major Influence ◽

Controlled Environment ◽

Crop Load

Growth of apple fruit can be described as an initial exponential phase lasting the 40+ days of fruit cell division followed by a more-or-less linear phase where growth is by cell expansion. Temperature is a major influence on fruit growth rate during the cell division phase, thereby affecting fruit size at maturity. However it is generally thought that temperature has less-direct impact on fruit development during the fruit expansion phase. Our observations of apple growth among regions and seasons of considerable climatic variability led us to speculate that temperature may impact directly on fruit development during fruit expansion but that responses may be interactive with carbon balance (crop load) influences. Controlled environment studies are being used to examine this hypothesis. Potted `Royal Gala' trees set to three levels of crop (one fruit per 250, 500, or 1000 cm2 leaf area) were grown from 56 to 112 DAFB in day/night temperature regimes of 18/6, 24/12, and 30/18 °C. All trees grew in field conditions prior to and following the controlled environment treatments. Treatments were harvested when 20% to 25% of fruit on trees showed the visual indicators used commercially to indicate harvest maturity. Fruit were evaluated using attributes that determine quality and that may have implications for fruit post harvest behaviour. Temperature and crop load influences on time to maturity, fruit fresh and dry weight, fruit DM content, fruit firmness, fruit airspace content and estimated fruit cortical cell size will be presented and implications discussed.

Download Full-text

Crop Load Affects Mineral Concentrations and Incidence of Bitter Pit in `Cox's Orange Pippin' Apple Fruit

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.117.3.373 ◽

1992 ◽

Vol 117 (3) ◽

pp. 373-376 ◽

Cited By ~ 43

Author(s):

I.B. Ferguson ◽

C.B. Watkins

Keyword(s):

Inverse Relationship ◽

Fruit Size ◽

Apple Fruit ◽

Postharvest Storage ◽

Crop Load ◽

Fruit Maturity ◽

Bitter Pit ◽

Mineral Concentrations ◽

Storage Disorders

Apple fruit (Malus domestics Borkh. cv. Cox's Orange Pippin) were harvested in four orchards from trees growing under the same conditions but differing in crop load. Regardless of fruit size, apples from light-cropping trees had lower Ca and higher K concentrations and more bitter pit than did fruit from trees with heavy crop loads. The inverse relationship between Ca concentration in the fruit and the incidence of bitter pit also varied according to crop load and could affect the ability to predict incidence of bitter pit from Ca measurements. Differences in fruit maturity that would influence bitter pit incidence were not associated with crop load. The enhanced susceptibility to storage disorders, such as bitter pit, in fruit of all sizes from light-cropping trees suggests the need to handle fruit from such trees differently for postharvest storage.

Download Full-text

251 The Effect of Simulated Stress on the Yield and Size of `Gala' and `Empire' Apple

HortScience ◽

10.21273/hortsci.34.3.485d ◽

1999 ◽

Vol 34 (3) ◽

pp. 485D-485

Author(s):

S.L. Breitkreutz ◽

J.A. Flore

Keyword(s):

Total Yield ◽

Fruit Size ◽

Growing Season ◽

Apple Fruit ◽

Physiological Status ◽

Crop Load ◽

Pest Damage ◽

Biological Stress ◽

Foliar Damage ◽

Current Standards

Pest damage to apple fruit is intolerable by our current standards. However, the effects of foliar damage on the plant's physiological status and fruit quality are not thoroughly understood. The objective of this work was to determine the time during the growing season when apple trees are most susceptible to foliar damage. Terbacil (50 ppm), an inhibitor of photosynthesis, was applied to 8-year-old `Gala'/Mark planted at 6 ×18-foot spacing or 14-year-old `Empire'/M106 planted at 18 × 20-foot spacing at 20- to 30-day intervals from petal fall until harvest to simulate environmental or biological stress. The work was conducted from 1995 through 1998. Photosynthesis was inhibited by 50% to 80% within 24 h of application of Terbacil but recovered to control levels 10 to 14 days after. The fruit were evaluated at harvest for total yield, size of fruit, and fruit number. Terbacil induced fruit abscission when applied at petal fall but not at later dates. The earlier the application, the greater the effect on current seasons yield and fruit size depending on crop load. For `Gala', there was a reduction in yield at petal fall of 30% to 70% over the control trees. Further detailed results will be presented.

Download Full-text

Characterizing the Interaction between NAA and BA on Apple Fruit Abscission and Development

HortScience ◽

10.21273/hortsci.43.6.1794 ◽

2008 ◽

Vol 43 (6) ◽

pp. 1794-1801 ◽

Cited By ~ 3

Author(s):

Martin J. Bukovac ◽

Paolo Sabbatini ◽

Philip G. Schwallier ◽

Michael Schroeder

Keyword(s):

Strong Interaction ◽

Fruit Size ◽

Apple Fruit ◽

Fruit Growth ◽

Crop Load ◽

Fruit Thinning ◽

Small Fruit ◽

Golden Delicious ◽

Fruit Formation ◽

Fruit Diameter

NAA and BA are important compounds for regulating crop load in apples (Malus domestica Borkh.). When used for fruit thinning, both induce abscission, but at an equivalent crop load NAA tends to reduce and BA to increase fruit size. There is a strong interaction between NAA and BA when used together on ‘Delicious’ and ‘Fuji’, leading to excessive development of pygmy and small fruit (<65 mm diameter). The combination of BA (as Promalin, 1:1 BA + GA4+7) applied at king bloom (KB) and NAAm (amide) at petal fall increased the percentage of small fruit by 3.3- or 5.1-fold compared with BA or NAAm alone. Similar results were obtained with BA (Promalin) at KB oversprayed with NAA at 10 to 12 mm king fruit diameter (KFD). When NAA was oversprayed with BA during fruitlet development, i.e., 5 to 6 mm, 10 to 12 mm, and ≈18 mm KFD, the greatest inhibition of fruit growth occurred at the 10- to 12-mm KFD stage, and there was no significant effect at 18 mm KFD. Inhibition by treatment at the 5- to 6-mm stage was intermediate and trees were overthinned. NAA + BA inhibition of fruit growth in ‘Delicious’ and ‘Fuji’ was not crop load-dependent. In all experiments, crop load (wt basis) of trees treated with NAA + BA was similar or less than of those treated with NAA or BA alone, but they produced 2.5- to 5-fold more small fruit. NAA + BA increased the number of fruit per cluster, many of which failed to fully develop. Increasing the ratio of BA to NAA from 25:15 to 125:15 mg·L−1 increased small fruit formation. The presence of GA4+7 in commercial formulations of BA (0:100, Maxcel; 10:100, Accel; 50:50, Promalin) did not significantly affect the NAA + BA response. Fruit growth was not inhibited by the NAA + BA combination in large-fruited ‘Golden Delicious’ and ‘Jonagold’ and was increased in small-fruited ‘Elstar’ and ‘Gala’ compared with the nontreated control.

Download Full-text