Increase in final fruit size of tangor ( Citrus reticulata × C. sinensis ) cv W. Murcott by application of benzyladenine to flowers

2017 ◽  
Vol 223 ◽  
pp. 38-43
Author(s):  
Carlos Ferrer ◽  
Johanna Martiz ◽  
Sebastian Saa ◽  
Ricardo Cautín
Keyword(s):  
Fruit Size ◽  
Citrus Reticulata

scholarly journals The Potential Use of Metamitron as a Chemical Fruit-thinning Agent in Mandarin

2018 ◽  
Vol 28 (1) ◽  
pp. 28-34 ◽  
Author(s):  
Ockert P.J. Stander ◽  
Johané Botes ◽  
Cornelius Krogscheepers
Keyword(s):  
Fruit Set ◽  
Fruit Size ◽  
Fruit Trees ◽  
Fruit Yield ◽  
Citrus Reticulata ◽  
Alternate Bearing ◽  
Fruit Thinning ◽  
Total Carbohydrates ◽  
Leaf Carbohydrates ◽  
Potential Use

Under conditions of profuse flowering and excessive fruit set, citrus (Citrus sp.) fruit need to be thinned to increase the size of remaining fruit, reduce the intensity of alternate bearing, or both. Metamitron was recently developed as a chemical fruit-thinning agent for apple (Malus ×domestica) and pear (Pyrus communis), and it inhibits photosynthesis and is thought to transiently reduce the carbohydrate pool in fruit trees. Citrus trees are sensitive to carbohydrate stress during and immediately after flowering, but the response of citrus to foliar treatment with a photosynthesis inhibitor, such as metamitron, is unknown. The purpose of this study was to evaluate metamitron for its effects on leaf carbohydrates and its ability to chemically thin citrus fruitlets. Significant fruit-thinning effects were found in all the experiments conducted over two seasons. A 300 mg·L−1 metamitron treatment reduced leaf sugars and leaf total carbohydrates, and consistently reduced the total number of fruit per tree in both seasons in ‘Nadorcott’ mandarin (Citrus reticulata), irrespective of the timing of application. In the second season, a reduction in fruit yield was reported with an increase in metamitron concentration, both in mass and number of fruit per tree. A 150 mg·L−1 metamitron treatment in November had no fruit-thinning effects, and fruit yield was not different from the control. The application of metamitron did not increase the fruit size of ‘Nadorcott’ mandarin and had no direct effect on other fruit quality attributes in either season. Metamitron can be used as a chemical fruit-thinning agent to reduce fruit numbers in ‘Nadorcott’ mandarin, but an increase in fruit size or quality should not be expected.

scholarly journals Fruit Size and Yield of Mandarins as Influenced by Spray Volume and Surfactant Use in NAA Thinning

HortScience ◽  
2006 ◽  
Vol 41 (6) ◽  
pp. 1435-1439
Author(s):  
Ed Stover ◽  
Scott Ciliento ◽  
Monty Myers ◽  
Brian Boman ◽  
John Jackson ◽  
...  
Keyword(s):  
Nonionic Surfactant ◽  
Lower Cost ◽  
Fruit Size ◽  
Yield Reduction ◽  
Citrus Reticulata ◽  
Mature Trees ◽  
Lower Volume ◽  
Spray Volume ◽  
Potential Losses ◽  
Florida Citrus

Six trials were conducted to determine whether lower spray volumes or inclusion of different surfactants would permit adequate thinning of mandarin hybrids (Citrus reticulata hybrids) at a much lower cost per hectare. Sprays were applied using a commercial airblast orchard sprayer during physiological drop when fruitlets averaged 8 to 16 mm in diameter. Surfactant was always included at 0.05% v/v. NAA always reduced fruit per tree, increased fruit size, and decreased production of smallest size fruit. However, in only three experiments, contrast of all NAA treatments vs. controls indicated increased production of the largest (80–100 fruit per carton) and most valuable fruit. In four of five experiments, comparison of spray volumes of 600 (only examined in three of four experiments), 1200, or 2300 L·ha–1 demonstrated significant fruit size enhancement from all NAA applications. Most individual NAA treatments resulted in fewer fruit per tree, but there were no statistically significant differences between NAA treatments at different spray volumes. In only one of the four experiments, there was a marked linear relationship between spray volume and fruit per tree, yield, mean fruit size, and production of largest fruit sizes. The effects of surfactants (Activator, a nonionic, Silwet L-77, and LI-700) on NAA thinning were tested in both `Murcott' and `Sunburst'. In comparisons between Silwet L-77 and Activator surfactant, one experiment with `Murcott' showed greater fruit per tree and yield reduction from using Silwet, but with a smaller increase in production of largest fruit sizes, whereas in another `Murcott' experiment, Silwet L-77 reduced numbers of smaller fruit size with no increase in production of larger fruit. Based on these findings, current recommendations for NAA thinning of Fla. mandarins are use of spray volume of ≈1100–1400 L·ha–1 on mature trees with proportionally lower volume on smaller trees. These data appear to support use of a nonionic surfactant rather than other tested surfactants in NAA thinning of Florida mandarins. Because experience with NAA thinning of Florida citrus is limited, it is only recommended where the disadvantages of overcropping are perceived to substantially outweigh the potential losses from overthinning.

Effect of Fall/Winter Application of Foliar Urea on Flowering and Yield of `Nour' Clementine Mandarine

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 549c-549
Author(s):  
M. El-Otmani ◽  
A. Ait-Oubahou ◽  
A. Tadili ◽  
M. El-Hila ◽  
C.J. Lovatt
Keyword(s):  
Fruit Set ◽  
Fruit Size ◽  
Citrus Reticulata ◽  
Flower Number ◽  
Small Fruit ◽  
Foliar Urea ◽  
Fruit Load

Experiments were established using clementine (Citrus reticulata Blanco) groves to evaluate effect of urea application (at 0%, 0.8%, and 1.6%) during the period from October to February on flowering and yield. Urea significantly promoted flowering when applied during the period from the end of December to early February. October treatment had no effect, but November treatments somewhat increased inflorescence numbers. “Off year” trees (i.e., trees that have a small fruit load resulting from the previous spring flowering) produced more inflorescence than “on year” trees (i.e., trees with heavy fruit load from flowering of the previous spring), and urea enhanced flowering on both tree types. Flower number per inflorescence increased significantly more on “on year” trees irrespective of the type of inflorescence. Fruit set was significantly increased for trees receiving urea treatments from November on, with the greatest increase observed for the December/January treatments. Fruit size was increased significantly more by the January treatment than for the December application, whereas the October and November treatment had no effect on these parameters. Consequently, both earliness and export yield were improved with urea.

scholarly journals Mechanical Thinning of Mandarins with a Branch Shaker

2020 ◽  
Vol 30 (6) ◽  
pp. 745-750
Author(s):  
Coral Ortiz ◽  
Antonio Torregrosa ◽  
Enrique Ortí ◽  
Sebastià Balasch
Keyword(s):  
Research Study ◽  
Fruit Size ◽  
Citrus Fruit ◽  
Fruit Yield ◽  
Citrus Reticulata ◽  
Labor Costs ◽  
Thinning Operation ◽  
Thinning Operations ◽  
Mechanical Thinning ◽  
Increase Efficiency

Thinning is the process of removing some flowers or fruit to increase fruit size at harvest. In the Valencia region of Spain, the thinning operation for citrus fruit (Citreae) is performed for some mandarin varieties. This is always performed manually; however, this method is very expensive. The goal of this research study was to assess the mechanical thinning of mandarin (Citrus reticulata) using a hand-held branch shaker. Different thinning treatments were conducted over a 3-year period. The gasoline-powered branch shaker was capable of detaching fruit four- to five-times faster than manual thinning. Final fruit size was significantly higher using manual and mechanical thinning compared with a no thinning treatment. Similar final fruit size was obtained with manual and mechanical thinning. However, no significant differences were found in final fruit yield by weight among no thinning, mechanical thinning, and manual thinning treatments. The use of a branch shaker could be recommended for thinning operations to increase efficiency, reduce labor costs, and obtain larger and higher-quality fruit.

Citrus Irrigation Management

EDIS ◽  
2017 ◽  
Vol 2017 (5) ◽  
Author(s):  
Davie Mayeso Kadyampakeni ◽  
Kelly T. Morgan ◽  
Mongi Zekri ◽  
Rhuanito Ferrarezi ◽  
Arnold Schumann ◽  
...  
Keyword(s):  
Water Stress ◽  
Physiological Activity ◽  
Irrigation Management ◽  
Fruit Size ◽  
Irrigation Scheduling ◽  
Leaf Expansion ◽  
Tree Canopy ◽  
Limiting Factor ◽  
Irrigation Frequency ◽  
Citrus Production

Water is a limiting factor in Florida citrus production during the majority of the year because of the low water holding capacity of sandy soils resulting from low clay and the non-uniform distribution of the rainfall. In Florida, the major portion of rainfall comes in June through September. However, rainfall is scarce during the dry period from February through May, which coincides with the critical stages of bloom, leaf expansion, fruit set, and fruit enlargement. Irrigation is practiced to provide water when rainfall is not sufficient or timely to meet water needs. Proper irrigation scheduling is the application of water to crops only when needed and only in the amounts needed; that is, determining when to irrigate and how much water to apply. With proper irrigation scheduling, yield will not be limited by water stress. With citrus greening (HLB), irrigation scheduling is becoming more important and critical and growers cannot afford water stress or water excess. Any degree of water stress or imbalance can produce a deleterious change in physiological activity of growth and production of citrus trees.  The number of fruit, fruit size, and tree canopy are reduced and premature fruit drop is increased with water stress.  Extension growth in shoots and roots and leaf expansion are all negatively impacted by water stress. Other benefits of proper irrigation scheduling include reduced loss of nutrients from leaching as a result of excess water applications and reduced pollution of groundwater or surface waters from the leaching of nutrients. Recent studies have shown that for HLB-affected trees, irrigation frequency should increase and irrigation amounts should decrease to minimize water stress from drought stress or water excess, while ensuring optimal water availability in the rootzone at all times.

Antimicrobial and cytotoxic activity of Macrophomina phaseolina isolated from gummosis infected citrus reticulata

2013 ◽  
pp. 125-133
Author(s):  
Rubal C Das ◽  
Rajib Banik ◽  
Robiul Hasan Bhuiyan ◽  
Md Golam Kabir
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Brine Shrimp ◽  
Inhibitory Concentration ◽  
Lethal Dose ◽  
Macrophomina Phaseolina ◽  
Chloroform Extract ◽  
Citrus Reticulata ◽  
Gram Negative Bacteria ◽  
Gram Negative

Macrophomina phaseolina is one of the pathogenic organisms of gummosis disease of orange tree (Citrus reticulata). The pathogen was identified from the observation of their colony size, shape, colour, mycelium, conidiophore, conidia, hyaline, spore, and appressoria in the PDA culture. The crude chloroform extracts from the organism showed antibacterial activity against a number of Gram positive and Gram-negative bacteria. The crude chloroform extract also showed promising antifungal activity against three species of the genus Aspergillus. The minimum inhibitory concentration (MIC) of the crude chloroform extract from M. phaseolina against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Shigella sonnie were 128 ?gm, 256 ?gm, 128 ?gm and 64 ?gm/ml respectively. The LD50 (lethal dose) values of the cytotoxicity assay over brine shrimp of the crude chloroform extract from M. phaseolina was found to be 51.79 ?gm/ml. DOI: http://dx.doi.org/10.3329/cujbs.v5i1.13378 The Chittagong Univ. J. B. Sci.,Vol. 5(1 &2):125-133, 2010

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