الفهرس 
Introduction
Importance of nitrogen and phosphorus fertilizationOnly 14 pages are availabe for public view
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Abstract
This experiment was carried out during the two successive seasons of 2013 and 2014 to study the effect of using bio and organic, as well as, slow release fertilizers on growth and fruiting of Manfalouty pomegranate trees. Trees were planted at spacing 5x5 meters 33 years old and grown in the experimental orchard of Faculty of Agriculture, Assuit University. The texture of the tested soil is clay with a water depth not less than two meters and surface irrigation system was followed in the orchard.
This experiment included two factors (N and P). The first factor (N) comprised six application from mineral, organic, bio-form and slow release of nitrogen fertilization, as following:
N1- Applying the recommended nitrogen dose (RDN) at 600 g N/tree as mineral source (1.8 kg ammonium nitrate 33.3 N/tree, check treatment, control).
N2- Applying 100% of RDN as slow release (1.5 kg Enciaben 40% N/tree).
N3- Applying 80% of RDN as slow release (1.2 kg Enciaben 40% N/tree).
N4- Applying 60% of RDN as slow (0.9 kg Enciaben 40% N/tree).
N5- Applying 60% of RDN as 10% mineral and 50% bio (300 gm Azotin, tree two forms).
N6- Applying 60% of RDN as 10% mineral plus 25% bio (150 gm Azotin) and 25% slow release tree (three forms).
Whereas, the second factor (P) involved five treatments of mineral, organic and bio-potassium fertilizers, as following:
P1- Application of the recommended rate of P (650 g calcium super-phosphate tree, 15% P2O5) as mineral source.
P2- Fertilization with mycorrhizal 40 ml/tree.
P3- Fertilization with mycorrhizal 20 ml/tree.
P4- Fertilization with phosphoren (P-dissolved bacteria) 180 ml/tree.
P5- Fertilization with phosphoren (P-dissolved bacteria) 90 ml/tree.
The organic-N fertilizer was added once in the last week of December. The slow release-N fertilizer (Enciaben 40%) was added once during the spring growth in the first week of March. Azotin was added in two equal batches at growth start and one month later. Mineral-N was added at three times in the first week of March, May and August. Calcium super phosphate was applied once in December. Phosphoren as a bio-fertilizer and mycorrhizal (VAM), solution of Golomus sp. and Amantia sp. were applied once at growth starts. The bio-fertilizers were prepared by mixing it with moist sand before the applications, added in soil holes around the trunk of the tree and then directly irrigated after covering the holes with soil.
Therefore, the experiment involved 30 treatments (6x5), each treatment was replicated three time, one tree per each. Hence, 90 healthy trees with no visual nutrient deficiency symptoms were chosen and devoted to achieve this experiment. Completely randomized block design in split plot arrangement was followed.
The tested treatments were evaluated through the following measurements during the two studied seasons.
1- Some vegetative growth parameters.
2- Leaf nutritional status (NPK).
3- Yield and yield components.
4- Fruit quality.
The nearly same obtained results in the two studied seasons could be summarized under the following main items.
1- Effect of different sources of nitrogen and phosphorus fertilizers on vegetative growth:
1.1- Shoot length and leaf traits:
Using 60% out of the recommended dose of nitrogen (RDN) via either 10% mineral-N plus 50% bio-form (two forms) or 10% mineral-N plus 25% bio and 25% slow release (three forms) significantly decreased the shoot length compared to using RDN as 100% slow release-N. No significant differences were observed on shoot length due to use any studied fertilization treatments compared to 100% mineral-N, check treatment. Slow release-N as well as two forms or three forms increased the number and area of leaves. Such effect gave a pronounced increment in leaf surface expansion. Since leaf is the site of carbohydrate manufacturing so leaf area is a great importance for tree growth and productivity.
Shoot length, leaf number/shoot and the leaf area were significantly increased by inoculating the soil with mycorrhizal at 20 or 40 ml/tree as well as phosphoren at 90 or 180 ml/tree compared to fertilize with recommended dose of phosphorus (RPD) via mineral source.
All combinations of 40 ml mycorrhizal application gave the highest values of shoot length and number of leaves. Also all combination of 180 ml phosphoren gave the highest values of leaf area. Moreover, all combination of mycorrhizal or phosphoren significantly increased the shoot length and leaf traits than any combined with calcium superphosphate applied as a check treatment.
The improvement of shoot length as well as number and area of leaves occurred due to using slow release accompanied with mycorrhizal or phosphoren as a source of phosphorus was more than improvement due to individual effects of either slow release-N as well as inoculation with mycorrhizal or phosphoren.
1.2- Nutrient contents:
Using either slow release, two (double) forms or three (triple) forms significantly increased of N, P and K in leaves compared to use RDN as mineral source only. No significant differences were observed on the percentage of N, P and K on leaves due to use 100 or 80% of RDN as slow release, as well as double forms or triple forms. It could be concluded that slow release-N as well as double forms or triple forms improved the nutritional status of trees. Such effect gave a pronounced increment in vegetative vigor, growth and productivity of trees.
The percentage of N, P and K in leaves were significantly increased by inoculating the soil with mycorrhizal at 20 or 40 ml/tree as well as phosphoren at 90 or 180 ml/tree compared to fertilize with recommended dose of phosphorus (RPD) via mineral source.
The highest N% was obtained due to use mycorrhizal at 20 or 40 ml compared to fertilize by 90 or 180 ml phosphoren/tree. Using mycorrhizal or phosphoren as bio-phosphorus sources significantly increased the percentage of P and K of leaves compared to using RPD as mineral source. The increment was associated with increasing mycorrhizal or phosphoren concentrations.
All combinations of inoculation with 40 ml mycorrhizal gave the highest percentage of N, P and K of leaves. Moreover, all combination of mycorrhizal or phosphoren significantly increased the leaf N, P and K percentages than any combined with calcium superphosphate applied as a check treatment.
The increasing leaf N, P and K percentages occurred due to using double or triple forms fertilizers accompanied with mycorrhizal or phosphoren as a source of phosphorus was more than improvement due to individual effects of either double or triple forms as well as mycorrhizal or phosphoren.
2- Effect of different sources of nitrogen and phosphorus fertilizers on fruiting:
2.1- Yield and fruit splitting:
Using the recommended dose of nitrogen (RDN) via either 100% slow release, 80% slow release or 60% slow release as well as, 10% mineral-N plus 50% bio-form (double forms) or 10% mineral-N plus 25% bio and 25% slow release (triple forms) significantly increased the yield/tree compared to using RDN as 100% mineral-N source only. No significant differences were observed on yield/tree due to use slow release-N at 100%, 80% or 60% of RDN.
On the other hand, the all fertilization treatments significantly decreased the fruit splitting percentage compared to applying the RDN as mineral-N (check treatment).
Yield/tree was significantly increased by inoculating the soil with mycorrhizal at 20 or 40 ml/tree as well as phosphoren at 90 or 180 ml/tree compared to fertilize with recommended dose of phosphorus (RPD) via mineral source. On other hand, the fruit splitting percentage took an adverse trend, where it significantly decreased. It could be concluded that mycorrhizal or phosphoren were effective in increases the weight of yield/tree and decreases the fruit splitting %, such effects gave a pronounced increase in the packable yield.
All combination of mycorrhizal or phosphoren significantly improved the yield/tree and fruit splitting % than any combined with calcium superphosphate applied as a check treatment. All combinations of 180 ml phosphoren application gave the highest values of yield/tree and least percentage of fruit splitting.
As, an overview, the results declared that the increasing the yield/tree and decreasing the fruit splitting percentage occurred due to using slow release, double forms or triple forms accompanied with mycorrhizal or phosphoren as a source of phosphorus was more than improvement due to individual effects of either slow release-N, double forms or triple forms as well as mycorrhizal or phosphoren.
2.2- Effect of different sources of nitrogen and phosphorus fertilizers on fruit quality:
2.2.1- Physical properties of fruits and chemical properties of peel:
Fertilization with any double form (mineral, plus bio), triple sources (slow release + bio + mineral) or slow release-N fertilizer significantly improved the physical fruit properties in terms of increasing the fruit weight, grains weight percentage, juice percentage and peel anthocyanin contents and decreasing peel tannin contents compared to using RDN as the release (mineral-N) source. No significant differences were observed in these traits due to fertilize as either slow release at any doses as well as mixture of the double forms or triple forms.
Fruit weight, grains weight (%), juice (%) and peel anthocyanin content were significantly increased by inoculating the soil with mycorrhizal at 20 or 40 ml/tree as well as phosphoren at 90 or 180 ml/tree compared to fertilize with recommended dose of phosphorus (RPD) via mineral source. On the other hand, peel tannin contents took an adverse trend, where, it significantly decreased.
All combinations of 40 ml mycorrhizal application gave the highest values of fruit weight, grains weight (%) and juice (%). As well as, all combination of 180 ml phosphoren gave the highest values of peel anthocyanin content and least values of peel tannin contents.
The improving of physical fruits and chemical peel properties occurred due to using either double forms or triple forms accompanied with mycorrhizal or phosphoren as a source of phosphorus was more than improvement due to individual effects of either double forms or triple forms as well as mycorrhizal or phosphoren.
2.2.2. Chemical constituents of juice:
Applying either, double form (mineral, plus bio), triple form (slow + bio + mineral) or slow release-N at 60 to 100 out of RDN significantly improved the juice chemical constituents in terms of increasing total soluble solids and reducing sugars as well as vitamin C and anthocyanin contents and decreasing the total acidity and tannin content compared to using RDN as the release-N source. It could be simply to see from data that total soluble solids were equivalent to reducing sugars, vitamin C and anthocyanin contents and reversed current with total acidity and tannin content. No significant differences were observed in most these traits due to fertilize as either two forms or 60-80% out RDN via slow release.
Total soluble solids, reducing sugars, vitamin C and anthocyanin content were significantly increased by inoculating the soil with mycorrhizal at 40 ml/tree, mycorrhizal at 20 ml/tree as well as phosphoren at 180 ml/tree or phosphoren 90 ml/tree compared to fertilize with recommended dose of phosphorus (RPD) via mineral source (P1) during the two studied seasons. On the other hand, total acidity and tannin content significantly decreased due to the premtnioned treatments.
The highest values of TSS, reducing sugars, vitamin C and anthocyanin contents and least values of total acidity and tannin contents were obtained due to use 180 ml phosphoren/tree.
All combinations of 180 ml phosphoren application gave the highest values of TSS, reducing sugars and anthocyanin content and least values of total acidity and tannin content. As well as, all combination of 40 ml mycorrhizal gave the highest values of vitamin C content. In other hand, all combination of calcium superphosphate gave the least values of TSS, reducing sugar, anthocyanin and vitamin contents and highest values of acidity and tannin contents, compared to other studied combinations.
The maximum values of TSS, reducing sugars and anthocyanin contents and least values of total acidity and tannin contents were found in trees fertilized with RDN via triple form or double form combined 180 ml phosphoren application.
At the same time all combination of 60% of out RDN whatever, slow release, double form or triple form significantly improved the chemical constituents of juice in terms of increasing total soluble solids, reducing sugar, vitamin C content and anthocyanin contents and decreasing the total acidity and tannin content compared to other combinations during the two studied seasons.
As, an overview, the results declared that the improving the chemical constituents of juice occurred due to using either triple form, double form slow release accompanied with mycorrhizal or phosphoren as a source of phosphorus was more than improvement due to individual effects of either triple form, double form or release-N as well as mycorrhizal or phosphoren.
Thus it can be concluded that using 60% of out RDN via slow release, double form (bio-plus mineral-N) or triple-forms of N (slow + bio plus mineral-N) accompanied with mycorrhizal or phosphoren were more effective in improving the chemical fruit properties, hence increased the packable yield of pomegranate.