Competition and fruit set in the Washington navel orange

Flowering, fruit set and fruit growth of 'Washington Navel' orange fruit was monitored on 24-year-old Citrus sinensis trees on Sweet orange rootstocks that had been irrigated with either 5 or 20 mol m-3 NaCl for 5 years preceding measurements.Trees irrigated with high salinity water had reduced flowering intensities and lower rates of fruit set. This resulted in final fruit numbers for trees irrigated with 20 mol m-3 being 38% those of trees irrigated with 5 mol m-3 NaCl. Final fruit numbers were quantitatively related to canopy leaf area for both salinity treatments.Despite little difference between trees in terms of leaf area/fruit number ratio, slower rates of fruit growth were initially observed on high salinity trees. This effect was not apparent during the latter stages of fruit development. Consequently, fruit on trees irrigated with 20 mol m-3 NaCl grew to the same size as fruit on trees irrigated with 5 mol m-3 NaCl, but achieved this size at a later date. Measurements of Brix/acid ratios showed that fruit on high salinity trees reached maturity standards 25 days after fruit on low salinity trees.Unimpaired growth of fruit on high salinity trees during summer and autumn occurred, despite appreciable leaf abscission, suggesting that reserve carbohydrate was utilized for growth during this period. Twigs on high salinity trees had much reduced starch content at the time of floral differentiation in winter. Twig starch content and extent of floral differentiation varied in a similar way when examined as a function of leaf abscission. This suggests that reduced flowering and fruit set in salinized citrus trees is due to low levels of reserve starch, most of which has been utilized to support fruit growth in the absence of carbohydrate production during summer and autumn.

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Effect of Foliar Application with Putrescine and Potassium Sulphate on Vegetative Growth, Fruit Set, Fruit Size, Fruit Quality and Yield of Washington Navel Orange

Current Science International ◽

10.36632/csi/2021.10.3.34 ◽

2021 ◽

Keyword(s):

Fruit Quality ◽

Vegetative Growth ◽

Fruit Set ◽

Foliar Application ◽

Fruit Size ◽

Navel Orange ◽

Potassium Sulphate ◽

Washington Navel

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Effect of Organic Fertilization on Fruit Set, Dropping, Yield and Fruit Quality of Washington Navel Orange

Journal of Plant Production ◽

10.21608/jpp.2017.40880 ◽

2017 ◽

Vol 8 (8) ◽

pp. 853-858

Author(s):

N. Samra ◽

M. EL–Kady ◽

A. Hikal ◽

M. Ghanem

Keyword(s):

Fruit Quality ◽

Fruit Set ◽

Navel Orange ◽

Organic Fertilization ◽

Washington Navel

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Effect of Urea, Some Micronutrients, and Growth Regulator Foliar Sprays on the Yield, Fruit Quality, and Some Vegetative Characters of Washington Navel Orange Trees: Fruit Pedicel Pectin Content, Flowering Aspects, and Fruit Set, and Dropping Percentages

HortScience ◽

10.21273/hortsci.30.4.880b ◽

1995 ◽

Vol 30 (4) ◽

pp. 880B-880

Author(s):

Ahmed M. Akl ◽

Abdel-Fattah M. Eid ◽

Mohamed Y. Hegab

Keyword(s):

Growth Regulators ◽

Fruit Quality ◽

Growth Regulator ◽

Fruit Set ◽

Navel Orange ◽

Fruit Drop ◽

Pectin Content ◽

Washington Navel ◽

Vegetative Characters ◽

Orange Trees

This part of the investigation studied the effect of foliar spraying with urea (0.5%); a mixture of Zn (0.4%), Mn (0.3%), Fe (0.5%), and Cu (0.3%) in sulphates (from 23% Zn, 28% Mn, 19% Fe, and 30% Cu, respectively); and two growth regulators (GA3 at 25 ppm and α-NAA at 10 ppm); as well as number and date of sprays on fruit pedicel pectin content, some flowering aspects, and fruit set and drop percentages. Applying urea, micronutrients, or both significantly increased pectin content in the pedicels of the attached and dropped fruit. The treatment including urea plus micronutrients resulted in the highest values for pectin in fruit stem. Either GA3 or NAA significantly raised pectin content over that of the water-sprayed control. However, NAA was more effective in increasing pectin content in fruit pedicel. The overall treatment including urea and micronutrients with GA3 or NAA was the most effective in producing the highest percentage of leafy inflorescence in 1991–92 and 1992–93 seasons. Any nutrition treatment was significantly effective in increasing fruit set and reducing fruit drop compared with the water-sprayed control; however, the treatment including all sprayed nutrients was the most effective. Application of GA3 or NAA significantly increased fruit set percentage and reduced June and preharvest fruit drop; however, NAA was more effective in reducing fruit drop than GA3.

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The development of cuttings of the Washington navel orange to the stage of fruit set. III. The fruiting cutting

Australian Journal of Agricultural Research ◽

10.1071/ar9611081 ◽

1961 ◽

Vol 12 (6) ◽

pp. 1081 ◽

Cited By ~ 1

Author(s):

CT Gates ◽

D Bouma ◽

H Groenewegen

Keyword(s):

Fruit Set ◽

Dominant Role ◽

Field Studies ◽

Nutrient Supply ◽

Navel Orange ◽

Developmental Studies ◽

Cycle Growth ◽

Washington Navel ◽

Npk Fertilization

Studies of the effect of NPK fertilization on fruiting cuttings of the Washington Navel orange are described and are considered in relation to previous developmental studies. Fruiting occurred on the second cycle growth flush. The growth of the plant as a whole was affected by nutrient supply. Where fruit was developed, its development was at the expense of the rest of the plant, and especially of the parts nearest to it. In this regard, the dominant role of the fruit with respect to the vegetative parts, differed from the somewhat uniform pattern of response between the vegetative parts that was previously observed for a differential in phosphorus supply. The importance of adequate nutrition in early stages of fruit development is apparent, and the value of the technique in field studies is noted.

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