Effect of Foliar Sprays with Ascorbic Acid on Flowering, Fruit Set and Yield of Washington Navel Orange Trees

2016 ◽  
Vol 7 (5) ◽  
pp. 519-529
Author(s):  
T. Mahmoud
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.


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

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