الفهرس 
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Abstract
Azolla is a genus of a small ferns that is native to Asia, Africa, and the Americas .The Azoll is a genus of heterosporous liptosporangiate fern from aquatic and semiaquatic habitats.
It can estimated that 10 kg of nitrogen per hectare per day, and thus has the potential of supplying the entire nitrogen requirement for a high-yielding rice crop within a few weeks. Under proper management and environmental condition, this rate can be sustained because Azolla reproduce by fragmentation and is not restrained by soil as are terrestrial plants. Azolla can also be used to suppress paddy weeds . It is effective when used as an organic fertilizer for some other crops Azolla can also used to feed fish and birds.
Due to the climate changes that have occurred in the environment and the continuous effort to achieve a balance between increasing production and preserving the environment by reducing the use of chemicals and to take maximum advantage of this plant this research dealt with a following points:
1- Selection of the most active medium for the growth of Azolla and its effect on Azolla biomass production.
2- Testing the effect of growing Azolla at different levels of salinity, as follows (0, 500, 1000, 1500, 2000, 2500) ppm on growth and productivity.
3- Testing the effect of using Azolla as a source of organic nitrogen in improving the quality of the compost produced.
4- Testing the effect of using Azolla as a dry manure, alone or with ammonium sulfate at different rates, on the growth and production of wheat plants.
Selection of the most active medium for the growth of Azolla:
In this experiment Azolla pinnata 7001 which supplied by Soils, Water and Environment Researches Institute, Department of Microbiology, Institute Agriculture Researches Center, Giza, Egypt. was cultivated on three different media (Yoshida, Soil and Watanabe media) to select the best medium having the highest growth rate and nutrient content of Azolla. five replicates for each treatment were carried out for 25 day. The samples were taken periodically after 5, 10, 15, 20 and 25 days to determine fresh and dry weights, doubling time, total nitrogen, phosphorus and potassium content.
Results could be summarized in the following:
1- Yoshida medium achieved the best results compared to the Watanabe and the soil medium in terms of nitrogen content as well as its content of protein, phosphorus and potassium during the growth period (25 days). Its content of these elements on day 25 was 4.40, 0.997, and 2.51 g/m2, respectively.
2- As for the fresh and dry weight, the Yoshida medium achieved the highest fresh and dry weight during the first 15 days, and they were 1017.36 and 57.98 g/m2, respectively. On the days 20 and 25, the Watanabe medium was the highest in terms of fresh and dry weight, and they were 1876.30 and 112.57 g. / m2, on day 25 respectively. Watanabe medium also recorded the shortest doubling time on day 25, was 4.9.
The effect of sodium chloride concentration on the growth and nutrients content of A. pinnata:
In this purpose, modified Yoshida medium was supplemented with different concentrations of Sodium chloride NaCl (0, 500, 1000, 1500, 2000 and 2500 ppm). Five replicates were carried out for each treatment . The samples were taken periodically after 5, 10, 15, 20 and 25 days to determine fresh and dry weights, doubling time, total nitrogen, phosphorus and potassium content.
Results could be summarized in the following:
1- The growth of Azolla in terms of fresh and dry weights decreased by increasing sodium chloride concentration. And The growth was completely inhibited on the 20th day of incubation in presence of 2000 ppm of salt and after 10 days in 2500 ppm. Also the doubling time increased by the time and by increasing salt concentration in all treatments.
2- Decreases the content of elements such as nitrogen, phosphorus and potassium with increasing salt concentration.
The role of Azolla as organic nitrogen source in improving of Compost Quality:
Two piles were prepared using date palm tree frond residues:
C1) Palm tree fronds + Azolla pinnata (500Kg dry Azolla/t plant residues) + microbial inoculum.
C2) Palm tree fronds + chemical activator (45kg ammonium sulfate +10 kg superphosphate /t plant residues) + microbial inoculum.
The amount of each material was calculated to attain a mixture of initial C/N ratio around 37: 1. The materials of each pile were thoroughly mixed for homogenization purpose, and the weight was about 150 kilogram for each pile. Maintained the moisture content between 50-60 % during the period of composting by watering. The composts were stirred every week to ensure having a good aeration. The composting process was continued for 11 weeks, including maturation period. Temperature degree was recorded every 2 days at depth 60 cm. The physical and chemical analyses including: moisture content, pH, EC, organic matter (OM), organic carbon (OC), total nitrogen (TN), C/N ratio, content of ash, ammonical-nitrogen (NH+4-N), nitrate (NO-3-N) total phosphorus (TP), total potassium (TK) were determined at zero time, 1 , 2 , 3 , 4 , 5 , 7 , 11 weeks of composting time.
Results could be conclude in the following:
1- The temperature gradually increased to reach its highest level of 67 and 68.340 C for C1 and C2, respectively, then it was decreased to 19.5 0 C by the end of the beam period for the two treatments.
2- The C/N ratio decreased from 37:1 to 16:1 and 18:1 for C1 and C2, respectively at the end of the composting perioed.
3- The electrical conductivity reached for both C1 and C2 at the end of the composting period to 2.60, 2.47 decisiemens-1. Also pH reached at the end of the period to 6.8 and 6 for both C1 and C2.
4- The initial value of total N in piles were 1.31 and 1.34 % for composting treatments C1 and C2 respectively. At the end of composting, all treatments showed increase for C1and C2 in total N content, recording: 1.78 and 1.70 % respectively, as a result of high biological oxidation and the quick and easy decomposition of carbohydrates.
5- The initial values of P percentages in early composting were 0.32 and 0.23 % for composting treatments C1 and C2, respectively. .At the end of composting, total P % were 0.54 and 0.50 % for C1 and
C2 respectively.
6- The initial values of K at early composting were 0.37 and 0.38 % for composting treatments C1 and C2 respectively .The concentrations of total potassium increased gradually in all mixtures by time, and ended to be 0.62 and 0.61 for C1 and C 2 respectively.
7- Percentages of OM in all composted materials decreased with time from 83.77to 48.21% in C1 and from 85.73 to 51.66 % in C2 respectively.
Effect of Azolla application in comparison to mineral-N as limited factor for wheat growth:
A pot experiment was carried out on wheat cv. Sids 14, during winter growing seasons of 2021/2022 and 2022/2023. Wheat (Triticum Aestivuml L) was planted to test the effect of Azolla as dry manure and ammonium sulfate application on plant growth and nitrogen uptake. Experiment was conducted in pots containing 7 kg air-dried sandy loam soil . The pot experiment consisted of 5 treatments in a completely randomized block design (CRBD) with 4 replicates. The following Treatments were tested
T1: Recommended dose of mineral N (110 Kg/fed.) as control.
T2: 75% mineral N (as Ammonium sulphate) + 25% organic N (as Azolla)
T3: 50% mineral N (as Ammonium sulphate) + 50% organic N (as Azolla)
T4: 25% mineral N (as Ammonium sulphate) + 75% organic N (as Azolla)
T5:100% organic N (as Azolla).
Plant samples were taken after 45 days from planting, and fresh and dry weights of shoot and root and nitrogen content were determined. At harvest, wheat yield components such as biological yield, number of branches, number of spikes, straw yield and grain yield were determined.
It could be concluded from the results obtained in the two seasons:
1. The highest values of both fresh and dry weight of shoot were recorded in treatment T1 (100% mineral-N) followed by T2 (75% mineral + 25% organic N (as Azolla) and the deference between them weren`t significant.
2. The highest value of the root fresh and dry weight were by treatment T4 (25% mineral N + 75% organic N (as Azolla) were (13.90, 5.27) and (15.77, 6.87) during both seasons respectively, flowed by treatment T3 (50% mineral N + 50% organic N as Azolla) were (13.02. 3.20) and (13.20, 4.55) for fresh and dry weight respectively.
3. The highest significant increase in N uptake was found in treatment T2 (75% mineral + 25% organic N (as Azolla) being (0.58 , 0.31) mg/pot flowed by T1 (100% mineral-N) which recorded 0.44 and 0.25 mg N/pot during both seasons, respectively with non-significant differences between them.
4. Treatment T1 (100% mineral-N) produced the highest grain weight per pot, however recorded 12.35 and 11.94 g/ pot during the both season, respectively. Also, it’s recorded the highest straw (25.09, 24.25 g/pot) and biological yield of wheat plants (37.40, 36.20 g/pot) during the both season respectively, flowed by treatment T2 (75% mineral + 25% organic N (as Azolla ) with non-significant differences between them.