Promoting fruit-set and yield in sweet orange using plant growth substances

1972 ◽  
Vol 12 (54) ◽  
pp. 96 ◽  
Author(s):  
GI Moss
Keyword(s):  
Gibberellic Acid ◽  
Fruit Set ◽  
Sweet Orange ◽  
Fruit Size ◽  
Growth Substances ◽  
Biennial Bearing ◽  
Small Fruit ◽  
Washington Navel ◽  
Fruit Size And Shape ◽  
Orange Trees

Experiments were done over four years to see if certain growth substances would increase the yields of sweet orange by increasing fruit-set. The main object was to find a method to increase yields during an off-year, and so control biennial bearing. Gibberellic acid (GA) was the most promising substance and under glasshouse and controlled environment conditions increased fruit-set when several applications were made, but had only a temporary effect when a single spray was applied. In the first instance a greater volume of fruit was produced although the mean size of the fruit was less. In the second instance some changes in fruit size and shape were found. In the field, a single spray (to part of a tree) of 400 p.p.m. GA at petal fall in one season on both Late Valencia and Washington Navel increased fruit-set, and in the following season 100 p.p.m. GA applied at petal fall increased fruit-set in Washington Navels. When a 50 p.p.m. GA spray was applied to whole Washington Navel trees in successive seasons there was a 20 per cent increase in the number of fruit harvested, but this was barely significant. However, there was a greater percentage of small fruit from the treated trees. This treatment had no effect the following season. Single applications of GA from 25 to 200 p.p.m. applied to Late Valencia trees from petal fall onwards in an 'off year' had relatively little effect. Some treatments retarded fruit-drop, but had insignificant or only minor effects on yield. Applying gibberellic acid to improve fruit-set is not a practical means for controlling yields of sweet orange trees.

The use of gibberellic acid to control alternate cropping of Late Valencia sweet orange

1977 ◽  
Vol 28 (6) ◽  
pp. 1041 ◽  
Author(s):  
GI Moss ◽  
KB Bevington
Keyword(s):  
Gibberellic Acid ◽  
Sweet Orange ◽  
Poncirus Trifoliata ◽  
Minimum Concentration ◽  
Rough Lemon ◽  
Small Fruit ◽  
Valencia Orange ◽  
Orange Trees ◽  
Long Term Adverse Effects

The effect of spraying commercial gibberellic acid (GA) on alternate cropping and yield of Late Valencia orange trees was studied in detail at three sites over three seasons. Two applications of GA were applied at a minimum concentration of 25 ppm (in two experiments 0.75% emulsifiable oil was used as an adjuvant) 3 weeks apart during April and May for Dareton (on the River Murray) or June and early July for Yanco (Murrumbidgee Irrigation Areas) prior to the heavy-crop blossom. These sprays partly inhibited flowering and the subsequent heavy crop was reduced by up to 22% (by fruit number). In the next season there were more flowers and the light crop was increased by up to 57% at Dareton and 228% at Yanco. Some treatments practically eliminated alternate cropping while all reduced considerably the heavyllight crop ratio. Mean weight yields over 2 years were increased by up to 17% at Yanco and 16% at Dareton with mean increases for all successful GA treatments of 12.6% and 7.2% respectively. This represented an increase of 34 and 24 kg fruitltree. No long-term adverse effects on yield were found.Apart from re-greening of the fruit present at the time of spraying, fruit quality was not affected. There were fewer non-saleable small fruit at Yanco in the heavy crop as a result of the GA treatments, and a better range of fruit sizes in both the heavy and light crops. Trees on Rough Lemon rootstock responded well to GA treatments, especially in terms of increased yield in the light crop. Poncirus trifoliata rootstock was less responsive than Sweet Orange. This method might be used for the commercial control of alternate cropping of Late Valencia orange trees.

scholarly journals 657 Relationship between Intensity of Flowering and Cropping in Fruit and Nuts

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 561C-561
Author(s):  
E.W. Stover
Keyword(s):  
Fruit Set ◽  
Fruit Size ◽  
Commercial Application ◽  
Critical Periods ◽  
Alternate Bearing ◽  
Crop Species ◽  
Fruit Thinning ◽  
Small Fruit ◽  
Substantial Investment ◽  
Flowering Intensity

The relationship between intensity of flowering and various aspects of cropping will be reviewed for fruit and nuts. Clearly, relatively light flowering can limit yield in most fruit and nut species. This commonly occurs before mature bearing commences and in “off” years for varieties that display alternate bearing. During mature bearing, many species will carry fruit numbers that exceed commercially desired levels, resulting in excessively small fruit and accentuating alternate bearing. The economic disadvantages of excess cropload have resulted in considerable research on fruit thinning and widespread commercial application of this practice. Heavy flowering intensity in some crop species results in economic disadvantages beyond the problems of excessive cropload and resultant small fruit size. Many species flower profusely and have initial fruit set far in excess of final tree capacity, resulting in abscission of numerous flowers and fruitlets. Abscised organs can represent a substantial investment in carbohydrates and nutrients, compromising availability at critical periods in flower and fruit development. The potential implications of this process are best exemplified in navel orange, where an increase in flowering beyond intermediate intensity results in a reduction in both initial fruit set and final fruit yield at harvest. In several crops, there is evidence that fruit size may be reduced by excessive flowering, even when cropload is quickly adjusted to an acceptable level. These data suggest that further research on the advantages of controlling flowering intensity is warranted.

scholarly journals 745 PB 079 SINK SIZE IN GAs-TREATED AND POLLINATED RABBITEYE BLUEBERRY FRUITS

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 539g-539
Author(s):  
Raouel Cano-Medrano ◽  
Rebecca L. Darnell
Keyword(s):  
Cell Size ◽  
Fruit Set ◽  
Fruit Size ◽  
Cell Number ◽  
Cross Sectional Area ◽  
Stage I ◽  
Stage Ii ◽  
Sectional Area ◽  
Cross Sectional ◽  
Small Fruit

Exogenous applications of GA, have induced pathenocarpic fruit set in blueberry; however, size of GA,-treated fruit is smaller than pollinated fruit. The small fruit size in GA3-treated fruit may be related to either cell number and/or cell size. Thus, these parameters were examined throughout development in pollinated, non-pollinated and GA3-treated fruits. Fruit growth followed a double sigmoid pattern. During Stage I (0-25 DAA), fruit size in GA,-treated, pollinated, and non-pollinated fruits averaged 0.33, 0.39, and 0.16 g, respectively. There was little change in fruit size in Stage II (25-45 DAA). At ripening, fruit size averaged 1.7 g for GA,-treated and 2.6 g for pollinated fruits. Non-pollinated fruit abscised in Stage II. At anthesis, mesocarp cell number averaged 9910 cells per median cross sectional area and remained constant up to ripening. In Stage I, cell size in G A3-treated and pollinated fruits increased 7X and 9X respectively. Cell size in both fruit types increased 1.5X and 2.8X during Stage II and Stage 111, respectively. Fruit cell number was set at anthesis and differences in fruit size were due to differences in cell ellongation in Stage I.

Growth, yield and fruit composition of Washington Navel and Late Valencia orange trees, as affected by rootstock and root temperature

1977 ◽  
Vol 17 (85) ◽  
pp. 336
Author(s):  
PR Cary ◽  
PGJ Weerts
Keyword(s):  
Sweet Orange ◽  
Growth Yield ◽  
Poncirus Trifoliata ◽  
The Other ◽  
Root Temperature ◽  
Rough Lemon ◽  
Washington Navel ◽  
C 30 ◽  
Increasing Temperature ◽  
Orange Trees

Wahington Navel and Late Valencia scions were budded onto three clonal rootstocks (rough lemon, sweet orange and Poncirus trifoliata) mist propagated and grown in sand. The six scion/rootstock combinations were grown in containers in a glasshouse with three root temperature treatments (19�C, 25�C, 30�C). Juvenile characteristics, evident for 5-6 years when scions are budded onto seedling rootstocks, were less marked when clonal rootstocks were used. Highest yield of fruit was produced by Late Valencia/sweet orange. This yield was 30 per cent better than previously obtained with Late Valencia grown from rooted cuttings under similar conditions. The yield from Washington Navel/sweet orange was about 30 per cent less than from Late Valencia/sweet orange; and the yields from the other scion/rootstock combinations were about 50 per cent of that from Washington Navel/ sweet orange. For most combinations more total dry matter was produced at a root temperature of 25�C than at 19�C, but there was little benefit from increasing temperature to 30�C. With either scion on rough lemon, fruit abscission was marked if root temperature treatments were imposed early (in late August). The effect was particularly severe at 25� and 30�C. Root temperature treatments for the other rootstocks were not imposed until mid-October when fruitlets were about 15 mm in diameter; under these conditions there was negligible fruit drop.

scholarly journals A preliminary evaluation of the effects of pollinator enhancement and gibberellins on the fruit set and fruit shape of ‘Conference’ pears – Short Communication

2020 ◽  
Vol 47 (No. 4) ◽  
pp. 211-216
Author(s):  
Jolien Smessaert ◽  
Gaby van Kemenade ◽  
Anneleen Arnoys ◽  
Olivier Honnay ◽  
Wannes Keulemans
Keyword(s):  
Short Communication ◽  
Fruit Set ◽  
Fruit Size ◽  
Fruit Shape ◽  
Pyrus Communis ◽  
Preliminary Evaluation ◽  
Size And Shape ◽  
Pyrus Communis L ◽  
Fruit Size And Shape

‘Conference’ (Pyrus communis L.) is a self-incompatible cultivar, although it can also set fruit parthenocarpically. Stimulating parthenocarpy through gibberellin (GA) applications increases the fruit set, but it may also negatively affect the fruit size and shape. The aim of this study was to investigate the effects of a bumblebee (BB) amendment in combination with a GA treatment on the fruit set and fruit shape of ‘Conference’ pears. In the first experiment, we applied three treatments (GA, GA + BB & control) in a ‘Conference’ monoculture. In the second experiment, we applied two treatments (GA & GA + BB) in a ‘Conference’ orchard inter-planted with ‘Concorde’ as pollinizer trees. Both experiments showed that the GA application and bumblebee supplementation did not affect the fruit set. However, the BB treatment resulted in significantly higher amounts of normally shaped pears. Trees closer to the bumblebee hive had more normal shaped pears than trees further away.

scholarly journals Fruit Set, Retention, and Developmental Rates Vary in Massachusetts Cranberry Cultivars

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 849E-849
Author(s):  
Carolyn J. De Moranville*
Keyword(s):  
Fruit Development ◽  
Fruit Set ◽  
Fruit Size ◽  
Growth Curves ◽  
Lag Phase ◽  
Variable Yield ◽  
Small Fruit ◽  
Developmental Rates ◽  
Hybrid Cultivar ◽  
Fruit Mass

Cranberry fruit development was studied in 3 years at the Univ. of Massachusetts Cranberry Station farm. Beginning at 4 weeks from 50% out of bloom and continuing until late Sept, 5 replicate samples of 25 fruiting uprights were collected biweekly from each of 7 cultivar beds. Fruit were removed from uprights and sorted into size classes using stacked soil sieves (16-, 12.5-, 9.5-, and 5.6-mm grids). Fruit from each class was counted and weighed. `Ben Lear', a native Wisconsin selection and the fourth most planted cultivar in Massachusetts, consistently produced the greatest yield (mass) of fruit. This was attributed to consistent fruit retention and large fruit size (majority of fruit at harvest were >12.5 mm in dia). In comparison, `Pilgrim', a large-fruited hybrid cultivar, was near the median for fruit yield due to poor fruit set (≈1.2 berries per upright compared to ≈1.6 for `Ben Lear'). `Stevens', the hybrid cultivar of choice in the MA cranberry industry, had yield similar to `Ben Lear' in only 2 of 3 years. Fruit set and retention in `Stevens' was less than that in `Ben Lear', but larger mass of individual fruit in `Stevens' generally made up for fewer fruit produced. Native cultivars `Early Black' and `Howes', which account for >50% of the MA cranberry acreage, had variable yield attributable to variable fruit set and retention by year. These cultivars bear small fruit (≈1 gm/berry; only half of berries >12.5 mm in diameter). Growth curves showed evidence of a `lag phase' in cranberry fruit mass accumulation occurring approximately at the mid-point of fruit development. Although much of the final fruit mass had accumulated by Sept, additional mass did accumulate up to the harvest of the beds (≈1Oct.). This has implications for growers who harvest fruit in early Sept for `white' cranberry juice.

scholarly journals Relationship of Flowering Intensity and Cropping in Fruit Species

2000 ◽  
Vol 10 (4) ◽  
pp. 729-732 ◽  
Author(s):  
Ed Stover
Keyword(s):  
Fruit Set ◽  
Fruit Size ◽  
Commercial Application ◽  
Critical Periods ◽  
Alternate Bearing ◽  
Crop Species ◽  
Fruit Species ◽  
Small Fruit ◽  
Full Production ◽  
Flowering Intensity

The relationship between intensity of flowering and various aspects of cropping are reviewed for fruit species. Relatively light flowering can limit yield in most fruit species. This commonly occurs in young trees that have not achieved full production and in “off” years for varieties that display alternate bearing. When trees mature, many species will carry fruit numbers that exceed commercially desired levels, resulting in excessively small fruit and accentuating alternate bearing. The economic disadvantages of excess cropload have resulted in considerable research on fruit thinning and widespread commercial application of this practice. Heavy flowering intensity in some crop species results in economic disadvantages beyond the problems of excessive cropload and resultant small fruit size. Many species flower profusely and have initial fruit set that greatly exceeds tree capacity, resulting in abscission of numerous flowers and fruitlets. Abscised organs can represent a substantial amount of carbohydrates and nutrients, compromising availability of these materials at critical periods in flower and fruit development. The potential implications of this process are best exemplified in `Navel' orange [Citrus sinensis (L.) Osbeck], where an increase in flowering beyond intermediate intensity results in a reduction in both initial fruit set and final fruit yield at harvest. In several species, there is evidence that fruit size may be reduced by excessive flowering, even when cropload is quickly adjusted to an acceptable level. These data suggest that further research on the advantages of controlling flowering intensity is warranted.

scholarly journals 518 Regulating Fruit Set and Maturity of `Macoun' Apples

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 535A-535
Author(s):  
J.R. Schupp
Keyword(s):  
Fruit Set ◽  
Fruit Size ◽  
Apple Cultivar ◽  
Fruit Firmness ◽  
Alternate Bearing ◽  
Northeastern United States ◽  
Fruit Characteristics ◽  
Small Fruit ◽  
Red Color ◽  
Fruit Maturity

`Macoun' is a high-value apple cultivar in the northeastern United States that is very difficult to produce. It is difficult to thin and prone to alternate bearing. `Macoun' is also prone to preharvest drop. Small fruit size, bruising, and lack of red color are additional obstacles to profitable production. The objective of this study was to compare the efficacy of two chemical thinning treatments—accel plus carbaryl, or NAA plus carbaryl—with an untreated control. A second objective was to evaluate the efficacy of ReTain for delaying `Macoun' fruit maturity and to determine if there was an interaction between ReTain and thinning treatment on fruit characteristics at harvest. Both thinning treatments were effective in reducing fruit set in 1997. Accel plus carbaryl was effective again in 1998, while NAA plus carbaryl over-thinned. Accel increased fruit size in 1997 compared to unthinned controls, and both thinning treatments increased fruit size in 1998. Accel increased fruit firmness in both years. ReTain reduced preharvest drop and delayed fruit maturity both years. In 1997, firmness was greatest for fruit treated with accel and ReTain, while ReTain had no effect on firmness of fruit from NAA thinned trees. ReTain had no effect on fruit firmness in 1998.

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