scholarly journals EFFECT OF HARVEST DATE ON FRUIT SET, DROPPING AND CHANGES IN NUTRENT AND ENDOGENS HORMONE OF WASHINGTON NAVEL ORANGE TREES

2015 ◽  
Vol 6 (1) ◽  
pp. 1-9
Author(s):  
A. Ibrahem
HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 880B-880
Author(s):  
Ahmed M. Akl ◽  
Abdel-Fattah M. Eid ◽  
Mohamed Y. Hegab

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.


HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 774D-774
Author(s):  
Ahmed M. Akl ◽  
Abdel-Fattah M. Eid ◽  
Mohamed Y. Hegab

This investigation was carried out during the experimental seasons of 1991–92 and 1992–93 on 25-year-old `Washington' navel orange trees grown in an orchard at Beni Suef (≈120 km south of Cairo). This part of the investigation studied the effect of foliar spraying urea (0.5%), a mixture of Zn (0.4%), Mn (0.3%), Fe (0.5%), and Cu (0.3%) in sulfates 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) on some vegetative aspects and leaf content of some macro- and micronutrients. The investigation also included the effect of number and date of spraying (one spray 3 weeks before flowering, one spray 4 weeks after fruit set, and two sprays at the two dates) on the studied traits. The results showed that the overall treatments included two sprays of urea, micronutrients (Zn, Mn, Fe, and Cu) and NAA at 10 ppm achieved the highest values for average leaf area and shoot diameter in both seasons. The treatment on shoot length was more effective when GA3 replaced NAA. Leaf analysis showed that the application of any of the nutrients was responsible for a pronounced increase in leaf content of that element, but reduced the contents of others. Growth regulator treatments lowered leaf content of the determined elements. However, all other treatments in this study reduced leaf content of P and K.


Hilgardia ◽  
1965 ◽  
Vol 36 (6) ◽  
pp. 297-311 ◽  
Author(s):  
H. Z. Hield ◽  
C. W. Coggins ◽  
M. J. Garber

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 774E-774
Author(s):  
Ahmed M. Akl ◽  
Abdel-Fattah M. Eid ◽  
Mohamed Y. Hegab

This investigation studied the effects of foliar sprays of urea (0.5%), a mixture of Zn (0.4%), Mn (0.3%), Fe (0.5%), and Cu (0.3%) in sulfates 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 the number of fruit/tree, average fruit weight, and yield/tree in kilograms. Spraying `Washington' navel orange trees with urea and/or micronutrients significantly increased the number of fruit/tree, average fruit weight, and yield/tree expressed in kilograms. However, the treatment including both of them was the most effective in 1991–92 and 1992–93. Application of GA3 and NAA effectively increased the value of the three traits compared with the control; however, spraying the trees with NAA was responsible for higher fruit numbers, while GA3 was more effective in increasing fruit weight. Two sprays of urea, micronutrients, and NAA (or GA3), the first applied 3 weeks before flowering and the second 4 weeks after fruit set, were more effective than spraying once at any of the two dates in producing high numbers of fruit/tree, average fruit weight and yield per tree by weight.


1975 ◽  
Vol 15 (72) ◽  
pp. 136 ◽  
Author(s):  
MC Stannard ◽  
JC Evans ◽  
JK Long

Washington navel orange trees on trifoliate orange rootstocks were inoculated at various ages with budwood from either severely dwarfed Washington navel trees with butt scaling caused by exocortis virus or moderately dwarfed Marsh grapefruit trees with no butt scaling. Dwarfing, measured by trunk girth, became apparent four seasons after inoculation, the butt scaling inoculum causing more pronounced dwarfing than the non-scaling inoculum. For both inocula, trees inoculated in the nursery were the most dwarfed, and yielded least, with trees inoculated in the field one, two, three or five years later being successively less dwarfed and high yielding. In a second experiment, Washington navel orange trees on trifoliate orange, which were carrying exocortis virus or were inoculated with it either in the nursery or later in the field, were planted in 1962 at a density of 835 ha-1. The field inoculated trees subsequently grew larger than the others. All were more dwarfed but yielded more heavily on a ground area basis during five years of cropping than exocortis-free trees planted at a normal density of 222 ha-1. Dwarfed trees developed butt scaling symptoms and periodically became unthrifty. The non-scaling form of dwarfing lends itself to the development of high density plantings of small trees with consequent benefits in management and high early production


1989 ◽  
Vol 40 (2) ◽  
pp. 371 ◽  
Author(s):  
H Howie ◽  
J Lloyd

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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