الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 159 |  |  |
| | | from | 159 | | |
Abstract
This study was conducted during the two consecutive seasons 2006 and 2007 on uniform in vigour Balady mandarin trees budded on sour orange rootstock in and grown in a private citrus orchard situated at Dayrout district, Assiut Governorate, where the soil is silty clay and well drained and with a water table not less than two meters deep tree spacing is 5 x 5 meters apart. Surface irrigation system was followed in the tested orchard. All horticultural practices except N fertilization were followed as usual.
The present experiment included :
1-Applications of the recommended rate of N ( R.R.) completely via inorganic source ( 3883.5 g ammonium sulphate ,N 20.6 %).
2-Application of 80% R.R. via inorganic N ( 3106.8 g ammonium sulphate ) plus 20% R.R. via organic N ( 7.4 kg Compost El-Neel 2.15% N)
3- Application of 80% R.R. via inorganic N ( 3106.8 g ammonium sulphate ) plus 20% R.R. via bioform (160 g Biogen /tree).
4-Application of 60% R.R. via inorganic N (2330.1 g ammonium sulphate /tree) plus 40% R.R. via organic N (14.8 kg compost El-Neel 2.15% N).
5-Application of 60% R.R. via inorganic N ( 2330.1g ammonium sulphate /tree) plus 40% R.R. via bioform ( 320g Biogen /tree)
6-Application of 60% R.R. via inorganic N ( 2330.1g ammonium sulphate /tree) plus 20% R.R. via organic N (7.4 kg compost El-Neel) plus 20% R.R. bioform (160g Biogen /tree)
7-Application of 20 % R.R. via inorganic N (776.7g ammonium sulphate /tree) + 40% R.R. via organic N (14.8 kg compost El-Neel /tree) plus 40% R.R. bioform ( 320 g Biogen /tree)
8- Application of the recommended of rate of N completely via organic N ( 37.2kg compost El-Neel/tree)
9-Application of the recommended rate of N completely via bioform (800g Biogen /tree)
Each treatment was replicated three times, one tree per each ammonium sulphate ( 20.6 % N ); Compost El- Neel ( 2.15 % N) and Biogen were applied as inorganic, organic and bioforms of N, respectively.
Ammonium sulphate was added at three equal batches on the first week of Feb, Apr. and June. Compost El-Neel and Biogen were added once at the first week of January and February , respectively.
Completely randomized block design was followed. During both seasons the following parameters were measured:
1-Leaf area ( cm2) .
2- Percentages of N, P and K in the leaves .
3-Percentages of initial fruit setting and fruit retention.
4- Yield / tree expressed in weight (kg.) and number of fruits per tree.
5- Fruit weight (g.) and dimensions ( height and diameter in cm)
6- Percentage of fruit peel weight and fruit peel thickness (cm.)
7- Percentages of total soluble solids, total acidity ( as a citric acid) as well as total and reducing sugars and vitamin C content ( mg/ 100 ml juice).
The nearly same obtained data in both seasons could be summarized under the following main items:
1- Leaf area:
Leaf area was reduced when N was added as 20 % inorganic + 40 % organic + 40 % bioform as well as when N was applied completely via organic or bioform rather than using N completely via inorganic form. It was greatly stimulated when the trees received N as 60 to 80 % inorganic plus 20 to 40 % organic and biofertilization rather than using N via 100% inorganic. The maximum values were recorded when the trees received N as 60 % inorganic + 20% organic + 20 % bioform. Supplying the trees with N as 100% biofertilization gave the minimum values.
2- Percentages of N, P and K in the leaves:
They were enhanced in response to supplying the trees with N as 60 to 80 % inorganic plus 20 to 40 % organic and biofertilization compared to using N as 100% inorganic. Decreasing percentages of inorganic form from 60 to 20 % and at the same times using 40% from organic and biofertilization resulted in great decline on the these nutrients. Supplying the trees with N via bio at 100 %; organic at 100% and inorganic at 100%, in ascending order caused an obvious promotion on these elements . The maximum values were recorded on the trees fertilized with N at 100% biofertilization.
3- Percentages of initial fruit setting and fruit retention:
Amending Balady mandarin trees with N as 60 to 80% inorganic plus to 40 % organic and biofertilization considerably improved percentages of initial fruit setting and fruit retention compared to using N as 100 % inorganic form. Fertilizing the trees with N through , 60 % inorganic + 20 % organic + 20 % bioform resulted in the maximum values. The minimum values were recorded on the trees fertilized with N or 100% biofertilization.
4- Yield / tree:
Yield of Balady mandarin trees expressed in weight (kg) and number of fruits / tree was positively affected by fertilizing the trees with N as 60 to 80 % inorganic plus 20 to 40 % organic and biofertilization compared to using each source alone. There was a great decline on the yield with decreasing percentages of inorganic source from 60 to 20 % . In descending order, fertilizing the trees with N as 100% inorganic, 100 % organic and 100% bioforms improved the yield. The maximum yield expressed in weight (kg.) and number of fruits per tree was recorded oin the trees received N as 60% inorganic + 20 % organic and 20% bioform. Using N via biofertilizaiton alone gave the minimum values.
5- Some physical and chemical characters of the fruits:
Fertilizing of Balady mandarin trees with N as 20 % inorganic + 40 % organic + 40 % bioforms as well as 100% bioform or 100 % organic effectively improved fruit weight and dimensions and decreased fruitr peel weight and thickness rather than appliocation of N completely via inorganic source or using N as 60 to 80 inorganic and 20 to 40 % organic and biofertilizatopn. The minimum fruit weight and dimensions was observed on the trees received N as a 60 % inorganic + 20 % organic + 20% bioform. Biofertilization only gave the maximum values.
Application of N as % 60 to 80 inorganic along with 20 to 40% organic and bioforms of N as well as 100% organic or 100% bioforms materially improved chemical quality of the fruits in terms of increasing total soluble solids, total and reducing sugars and vitamin C content and decreasing total acidity rather than application of N completely via inorganic form. In most cases the promotion on chemical quality characters was associated with decreasing the percentages of inorganic form 100 to 0.0% and at the same time increasing percentages of organic and biofertilization. Using N as 100% biofertilization gave the best results with regard to chemical quality characters. Using N completely via inorganic source gave unacceptable effects