Detection of apple fruit in an orchard for early yield prediction as a function of 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).

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

Tree Physiology ◽

10.1093/treephys/28.8.1255 ◽

2008 ◽

Vol 28 (8) ◽

pp. 1255-1261 ◽

Cited By ~ 70

Author(s):

A. Naor ◽

S. Naschitz ◽

M. Peres ◽

Y. Gal

Keyword(s):

Water Status ◽

Fruit Size ◽

Apple Fruit ◽

Crop Load

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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.

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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.

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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.

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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.

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Effect of non-chemical crop load regulation on apple fruit quality, assessed by the DA-meter

Scientia Horticulturae ◽

10.1016/j.scienta.2017.11.011 ◽

2018 ◽

Vol 233 ◽

pp. 526-531 ◽

Cited By ~ 3

Author(s):

Lena Peifer ◽

Samuel Ottnad ◽

Achim Kunz ◽

Lutz Damerow ◽

Michael Blanke

Keyword(s):

Fruit Quality ◽

Apple Fruit ◽

Crop Load ◽

Load Regulation

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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.

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684 Thinning and Crop Load Effects on Apple Fruit Growth

HortScience ◽

10.21273/hortsci.35.3.516e ◽

2000 ◽

Vol 35 (3) ◽

pp. 516E-517

Author(s):

Duane W. Greene

Keyword(s):

Growth Rate ◽

Pollen Germination ◽

Apple Fruit ◽

Fruit Growth ◽

Initial Assessment ◽

Crop Load ◽

Specific Chemical ◽

Load Effects ◽

Viable Seeds ◽

June Drop

Chemical thinners can be classified as either blossom thinners or postbloom thinners. Blossom thinners act by inhibit further pollination, pollen germination, or pollen tube growth. At petal fall it is not possible to distinguish between fruit that have been injured by blossom thinners, and those that will persist and continue to grow. The receptacles of blossom thinned fruit do not grow, whereas fruit that has not been treated and that also contain viable seeds, resumes growth within 4 to 6 days, depending upon temperature. Abscission of fruit treated with postbloom thinners does not usually occur until 1.5 to 3 weeks after application. Frequently, it is possible to identify fruit that will abscise and to make an initial assessment of thinning efficacy, within 4 to 6 days following application by measuring fruit growth rate. A reduction in fruit growth by as little as 15% to 20% less than rapidly growing fruit is usually sufficient to assume that the fruit will abscise sometime during the June drop period. The effects of specific chemical thinners on fruit growth and subsequent thinning will be discussed.

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