Control of alternate cropping of Valencia orange with ethephon and napthalene acetic acid

1978 ◽  
Vol 18 (90) ◽  
pp. 152 ◽  
Author(s):  
PT Gallasch
Keyword(s):  
Acetic Acid ◽  
South Australia ◽  
Fruit Weight ◽  
Mature Fruit ◽  
Crop Load ◽  
The Third ◽  
Load Following ◽  
Valencia Orange ◽  
Leaf Drop ◽  
Orange Trees

Three experiments were done in the Riverland district of South Australia with the aim of controlling alternate cropping of mature Valencia orange trees by chemical thinning. In experiment 1, 300 p.p.m. ethephon was applied in either October, November or December. In experiment 2, sprays of either 200, 250, 300 or 350 p.p.m. ethephon were applied in late November. In experiment 3, sprays of either ethephon, NAA or a mixture of both were applied in early December. Sprays of ethephon in December were more effective than in October, and resulted in a 40 per cent reduction of mature fruit weight in a heavy crop year. All concentrations of ethephon of 250 p.p.m, or more reduced the heavy crop load, and in the following year increased light crops. A 15 per cent reduction in crop load following sprays of 250 p.p.m, gave even cropping trees. Treated trees produced, over two years, 10 per cent more fruit weight than control trees. Fruit from treated trees were larger in the heavy crop year and smaller the following year. In the third experiment, 300 p.p.m. ethephon reduced the mature crop by 31 per cent and 500 p.p.m. NAA reduced it by 18 per cent. A mixture of the two chemicals effected a 51 per cent reduction in crop load, but the NAA did not significantly reduce leaf drop. NAA at 500 p.p.m. resulted in the most even cropping trees.

Effect of time of harvest on alternate cropping yields and fruit quality of Valencia orange trees

1978 ◽  
Vol 18 (92) ◽  
pp. 461 ◽  
Author(s):  
PT Gallasch
Keyword(s):  
Fruit Quality ◽  
South Australia ◽  
Mature Fruit ◽  
Late Season ◽  
Valencia Orange ◽  
The Common ◽  
Orange Trees ◽  
Early Harvest ◽  
Time Of Harvest

At Loxton, South Australia, early harvest of heavy, and late harvest of light, Valencia orange crops was compared with the common practice: early harvest of light and late harvest of heavy crops. These treatments were compared with two years of early, mid- or late season harvests. Early harvest of heavy and late harvest of light crops changed the 3.1:1.0 alternate cropping cycle to 1.1:10 and increased the light crop by 101 per cent compared with the common district practice which gave a 3.2 : 10 cycle. Consistent early and mid-season harvests reduced the alternate cropping ratio to 1.3 : 1.0 and 1.4 : 1.0 respectively, produced 14 per cent more fruit than the common district practice and avoided harvesting the light crop late, when fruit quality is poor. Mature fruit weights from trees consistently harvested late were 27 per cent lower than those trees harvested mid-season.

Attempts to control alternate cropping of Valencia orange by inhibiting flower formation with gibberellic acid

1978 ◽  
Vol 18 (91) ◽  
pp. 309 ◽  
Author(s):  
PT Gallasch
Keyword(s):  
Gibberellic Acid ◽  
No Reduction ◽  
South Australia ◽  
Flower Formation ◽  
Mature Fruit ◽  
Mature Trees ◽  
Valencia Orange ◽  
Orange Trees

Gibberellic acid (GA) was sprayed on whole Valencia orange trees in 1971 at Loxton in South Australia with the aim of reducing the size of the heavy crop and the alternate cropping cycle. Sprays were applied in June or July at 25 p.p.m. but there was no reduction in mature fruit weights in 1972. In 1973, sprays of GA at 25 p.p.m, were applied twice, about two weeks apart, commencing on either May 7 or 22. In the following November treated trees had 75 per cent fewer fruitlets, but by the time fruit were mature, trees had fully compensated for this early reduction in fruit numbers by increased set and reduced December drop. Again the weight of mature fruit was not reduced at the timings and concentrations used and hence GA cannot be recommended for the control of alternate cropping.

scholarly journals Naphthalene Acetic Acid and 2,3,5-triiodobenzoic Acid Affect the Response of Mature Orange Fruit to Abscission Chemicals

HortScience ◽  
2002 ◽  
Vol 37 (2) ◽  
pp. 348-352 ◽  
Author(s):  
Rongcai Yuan ◽  
Ulrich Hartmond ◽  
Walter J. Kender
Keyword(s):  
Acetic Acid ◽  
Abscission Zone ◽  
Naphthalene Acetic Acid ◽  
Mature Fruit ◽  
Fruit Abscission ◽  
Triiodobenzoic Acid ◽  
Valencia Orange ◽  
Auxin Concentration ◽  
Auxin Transport Inhibitor ◽  
Orange Fruit

Effects of NAA, TIBA, ethephon, and CMN-Pyrazole on fruit detachment force (FDF) of mature `Valencia' and `Hamlin' orange [Citrus sinensis (L.) Osb.] fruit were examined in 2000 and 2001. NAA effectively inhibited the reduction in FDF or fruit abscission caused by ethephon when applied to the abscission zone 24 hours before ethephon application, but had no significant effect when applied to the fruit without contacting the abscission zone, or to the peduncle ≈4 cm above the abscission zone. TIBA, an auxin transport inhibitor, decreased FDF of mature fruit and promoted fruit abscission when applied alone as a spray to the canopy or directly to the fruit peduncle. This response was dependent on TIBA concentration. TIBA was more effective when applied in combination with ethephon or CMN-Pyrazole than alone. These results are consistent with our previous data that endogenous auxin concentration in the abscission zone of mature `Valencia' orange fruit is one of the factors controlling the sensitivity and thus the responsiveness of the abscission zone of mature fruit to abscission chemicals. Chemical names used: 5-chloro-3-methyl-4-nitro-pyrazole (CMN-Pyrazole); 2-chloroethylphosphonic acid (ethephon); naphthalene acetic acid (NAA); 2,3,5-triiodobenzoic acid (TIBA).

scholarly journals Late-season `Valencia' Orange Mechanical Harvesting with an Abscission Agent and Low-frequency Harvesting

HortScience ◽  
2006 ◽  
Vol 41 (3) ◽  
pp. 660-663 ◽  
Author(s):  
Jacqueline K. Burns ◽  
Fritz M. Roka ◽  
Kuo-Tan Li ◽  
Luis Pozo ◽  
Richard S. Buker
Keyword(s):  
Citrus Sinensis ◽  
Low Frequency ◽  
Mature Fruit ◽  
Fruit Removal ◽  
Immature Fruit ◽  
Late Season ◽  
Valencia Orange ◽  
Significant Difference ◽  
Orange Trees

An abscission agent (5-chloro-3-methyl-4-nitro-1H-pyrazole [CMNP]) at 300 mg·L–1 in a volume of 2810 L·ha–1 was applied to Valencia orange trees [Citrus sinensis (L.) Osb.] on 22 May 2004. At this time, immature and mature fruit were present on the tree simultaneously. Three days after application, fruit were mechanically harvested using a trunk-shake-and-catch system. The power to the shaker head was operated at full- or half-throttle (FT or HT, respectively), and the duration of trunk shaking was 2 seconds at FT or 4 seconds at FT and HT. Mature fruit removal percentage and number of immature fruit removed, and fruitlet weight and diameter were determined. Mature fruit removal percentage with 2 seconds at FT or 4 seconds at FT harvesting ±CMNP, or 4 seconds at HT + CMNP was not significantly different and ranged between 89% to 97%. Harvesting at 4 seconds HT without CMNP removed significantly less mature fruit than any treatment. CMNP did not affect immature fruit removal by the trunk shaker. Harvesting at 4 seconds at HT removed significantly less immature fruit than 2 seconds at FT or 4 seconds at FT. No significant difference in fruitlet weight or diameter was measured between any trunk shaker harvest operation and CMNP treatment. Trunk shaking frequency was estimated to be 4.8 and 8.0 Hz at HT and FT, respectively. Yield in 2005 was determined on the same trees used for harvest treatments in 2004. CMNP did not impact yield. No significant difference in yield was seen between the hand-picked control and 4 seconds at HT, whereas yield in the remaining treatments was lower. The results demonstrate that CMNP application combined with low frequency trunk shaker harvesting can achieve high percentage of mature fruit removal with no significant impact on return yield of the following crop.

Regulating Valencia orange crops with CEPA (2-chloroethyl phosphonic acid) - preliminary studies

1974 ◽  
Vol 14 (71) ◽  
pp. 835 ◽  
Author(s):  
T GallaschP
Keyword(s):  
Phosphonic Acid ◽  
South Australia ◽  
Fruit Yield ◽  
Leaf Fall ◽  
Mature Fruit ◽  
Phytotoxic Effects ◽  
Valencia Orange

The effects of chemicals on fruitlet thinning of Valencia oranges were studied in two experiments at Loxton, South Australia. In the first experiment 50 p.p.m. 245T, 2000 p.p.m. N.A.A. and 250 or 1000 p.p.m. CEPA all caused significant thinning but 245T had phytotoxic effects. In the second experiment with several concentrations of CEPA, both 524 and 1048 p.p.m. caused significant leaf and fruitlet drop, whereas 262 p.p.m. caused a significant reduction of 55 per cent in mature fruit yield without any significant leaf fall.

scholarly journals Effect of Annual Defoliation on Yield, Juice Quality, Leaf Net Gas Exchange, Leaf Size, and Number in `Hamlin' and `Valencia' Orange Trees

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1146B-1146
Author(s):  
Rongcai Yuan ◽  
Francisco Garcia-Sanchez ◽  
Fernando Alferez ◽  
Igor Kostenyuk ◽  
Shila Singh ◽  
...  
Keyword(s):  
Leaf Area ◽  
Citrus Sinensis ◽  
Leaf Size ◽  
Fruit Weight ◽  
Fruit Yield ◽  
Soluble Solids ◽  
Juice Quality ◽  
Valencia Orange ◽  
Acid Ratio ◽  
Orange Trees

The effect of annual defoliation over two consecutive years on fruit yield, juice quality, leaf size, and number was examined in 11-year-old `Hamlin' and 13-year-old `Valencia' orange [Citrus sinensis (L.) Osb.] trees. Removal of up to 50% of the leaves in late November had no effect on fruit number, fruit weight, fruit yield, soluble solids yield, juice °Brix, and °Brix: acid ratio of juice in `Hamlin' oranges. In `Valencia' oranges, removal of up to 50% of the leaves in late March also did not affect °Brix or the °Brix: acid ratio of the juice, but decreased fruit yield and soluble solids yield. Leaf size was reduced by removal of 50% of the leaves in both cultivars. Removal of up to 50% leaves in late November had no significant influence on net CO2 assimilation (aCO2) of the subsequent spring flush leaves in early May in `Hamlin' oranges, whereas aCO2 of `Valencia' spring flush leaves in early May increased linearly with increasing levels of defoliation in late March. The results indicate that fruit yield, fruit quality, leaf size, and number were not negatively impacted when annual defoliations did not exceed 25% of the total canopy leaf area for `Valencia' and `Hamlin' oranges for two consecutive years. Overall, in whole `Hamlin' or `Valencia' orange trees, fruit weight increased linearly with increasing ratio of leaf area to fruit, suggesting that fruit enlargement depends on available photosynthate and can be limited by leaf area.

scholarly journals Shoot and Cluster Thinning Influence Vegetative Growth, Fruit Yield, and Wine Quality of `Sauvignon blanc' Grapevines

2002 ◽  
Vol 127 (4) ◽  
pp. 628-634 ◽  
Author(s):  
A. Naor ◽  
Y. Gal ◽  
B. Bravdo
Keyword(s):  
Leaf Area ◽  
Weight Ratio ◽  
Fruit Weight ◽  
Cluster Number ◽  
Wine Quality ◽  
Crop Load ◽  
Number Of Clusters ◽  
The Third ◽  
Cluster Thinning

Effects of two shoot densities (14 and 44 shoots/vine) and two crop levels (one and two fruit clusters per shoot) on yield, pruning weight, crop load, and juice and wine quality of field-grown `Sauvignon blanc' grape (Vitis vinifera L.) were studied in a factorial experiment over 3 years. Main shoot length, lateral shoot length and number, shoot diameter, leaf area per shoot, and specific leaf weight were greater at the lower compared with the higher shoot density for all years whereas pruning weight was significantly increased only in the third year. Crop yield increased proportionally with the number of clusters, up to 44 clusters per vine, by both shoot and cluster thinning; a lower rate of yield increase was apparent when the number of clusters per vine was increased further, probably because of increasing source limitation. Berry maturation was delayed in the 44 shoots per vine treatment. Unchanged soluble solids, higher total acidity, and lower pH in the 44-shoot vine treatment in the third year indicated that the effect of cluster number on the must quality was not due to delayed maturation. No effect of cluster number per shoot on vegetative parameters was apparent. Berry size and number were affected by cluster thinning only in the 44 shoot/vine treatment. Both the number of shoots per vine and the number of clusters per shoot affected wine sensory attributes. Herbaceous aroma scores increased with increasing pruning weight. The wine sensory evaluation score decreased with increasing crop load. Total wine sensory scores decreased with decreasing leaf area to fruit weight ratio below ≈18 cm2·g-1, whereas a critical value of the crop to pruning weight ratio, for wine quality, was not apparent. Crop load expressed as crop to pruning weight ratio (kg·kg-1) was highly correlated with fruit weight to leaf area ratio (g·cm-2) (r2 = 0.86), providing a biological rationale for the relevance of crop load and wine quality relations.

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