الفهرس 
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Abstract
Germination and pot experiments were carried out in the laboratory and green house of Soils and Water Department, Faculty of Agriculture, Assuit University to investigate the effect of biochar and spirulina algae extracts on the germination of marjoram seeds and the production of sweet basil and marjoram plants irrigated with fresh and saline water (5 dSm-1). Nine different extracts (distilled water as control, 5% BC, 5% hw BC, 10% BC, 10 % hw BC, HCl BC, KOH BC, SP and hw SP) were used in the germination experiment. Whereas, biochar was applied to soil of the pot experiments at the dose of 0 and 2% and spirulina algae extract was sprayed on the plants at a rate of 0 and 2.5 gL−1. The obtained results can be summarized as follow:
1- Germination experiment:
• Except for the 10% BC (HW) treatment which had the same effect of distilled water (control), all investigated treatments had an insignificant negative effect on marjoram seeds germination.
• BC extracted with HCl significantly decreased both germination index (GI) and speed of accumulated germination (SAG) by 19.7 and 20.6%, respectivey.
• The extraction of dissolved organic carbon from biochar with alkaline (KOH) was the most significantly effective treatment compared to acidic (HCl), distilled and hot water treatments.
• Spirulina extraction contained the least amounts of dissolved OC.
• There were no significant difference in the shoot length when using 0.1 M KOH solution, 5 % BC, 5% hw BC and 10% BC.
• Shoot length was increased by 54, 54, 52 and 58% using 0.1 M KOH solution, 5 % BC, 5% hw BC and 10% BC compared to control treatment, respectively.
• In the presence of HCl, SP, and hw SP extracts shoot length were significantly enhanced by 34, 35 and 41%, respectively, in comparison with the control treatment.
• The highest root length value was found in KOH extract and the lowest in the control treatment.
• Increasing the biochar dosage in the extract increased root length.
• The highest length of roots were recorded as follow: KOH< 10% BC < 10% hw BC < 5% BC < 5%hw BC< HCl < SP < SP hw.
2- Pot experiments
2-1 Effect of biochar (BC) and Spirulina algae extract (SP) on some soil properties under water salinity stress:
2-1-1 Soil pH
• All examined treatments decreased the pH of the soils irrigated with fresh or saline water and cultivated with sweet basil or marjoram plants.
• The value of the soil pH ranged between 6.87 and 7.62 for soil planted with sweet basil plant and 6.81 and 7.66 for soil planted with marjoram plants.
• The highest pH values were found in the control treatments of fresh water irrigated soils, while the lowest ones were found in soils treated with biochar and irrigated with saline water treatments.
• The addition of biochar to soil with or without spraying sweet basil and marjoram plants with spirulina extract (SP) significantly (p < 0.05) affected the soil pH of the tested soils.
• Soil pH decreased in all treatment irrigated with saline water when compared with the irrigated ones with fresh water.
2-1-2 Soil EC:
• Under the irrigation with fresh water, only spirulina treatments decreased soil EC when cultivated with sweet basil or marjoram pants
• The addition of SP to fresh water treatment reduced the soil EC by 8% for soil planted with sweet basil and 15% for soil planted with marjoram plants compared to fresh water control.
• The addition of BC to the soil irrigated with fresh water increased the soil EC by 23% in soils planted with sweet basil and marjoram plants compared with the control.
• Irrigation with saline water caused noticeable increase in soil EC with all treatments compared to fresh water.
• All examined treatments significantly decreased the EC of the soils irrigated with saline water and panted with sweet basil or marjoram pants.
• The best treatment causing significant reduction in soil EC was BC+SP treatment.
• The addition of BC+SP, SP or BC to soil irrigated with saline water decreased the soil EC by 38, 21 or 19% for soil planted with sweet basil and 36, 20 or 18% for soil planted with marjoram plants compared to soil irrigated with saline water without any addition.
2-1-3 Soil organic matter:
• The addition of biochar (BC) and/or Spirulina (SP) significantly (p < 0.05) increased the soil organic matter (SOM).
• The content of SOM can be arranged in the descending order as follow: BC >BC+SP > SP > C with both kinds of irrigation water and both tested plants.
• The lowest effect on increased soil organic matter compared to fresh water control treatment was due to the foliar spray of spirulina algae extract.
• Under the irrigation with fresh water, BC, SP and BC+SP increased SOM by 266, 77 and 227% in sweet basil soils and by 317, 148 and 292% in marjoram soil, respectively.
• Under the irrigation with saline water, BC, SP and CB+SP increased SOM by 267, 85 and 238% in sweet basil soils and by 330, 160 and 307% in marjoram soil, respectively.
2-1-4 Nutrient availability:
• Water salinity significantly (p < 0.05) affected nutrient availability in soil panted with sweet basil and marjoram plants.
• The soil irrigated with saline water contained more available nitrogen (N) and phosphorus (P) compared to fresh water irrigated soil, whereas, it contained less available potassium.
• The addition of BC decreased the soil available nitrogen by 35% in soil planted with sweet basil and 51% for soil planted with marjoram plants compared to the control under fresh water irrigation.
• The addition of biochar increased the available P and K by 17 and 52% respectively for soil planted with sweet basil and 13 and 62% for soil planted with marjoram plants compared to control under fresh water irrigation.
• SP addition decreased the soil available N by 20% for soil planted with sweet basil and 26% for soil planted with marjoram and irrigated with fresh water compared to the control.
• The application of SP extract increased soil available P and K by 65 and 6% for soil planted with sweet basil and 61 and 4 for soil planted with marjoram and irrigated with fresh water compared to the control.
• The addition of SP+BC with the irrigation with fresh water decreased the available soil nitrogen by 34% and 39% for soil planted with sweet basil and marjoram, respectively, compared to the control.
• SP+BC addition increased soil available P and K at rate of 74 and 50% for soil planted with sweet basil and 77 and 43% for soil planted with marjoram compared to fresh water control.
• Under saline conditions, there is an increase in available nitrogen and phosphorus by 16 and 17% for soil planted with sweet basil and 9 and 19% for soil planted with marjoram, respectively, compared with fresh water control.
• The effect of examined treatments on the availability of N, P and K was similar under saline irrigation water to that under fresh irrigation water. Available N can be arranged dissentingly as follow: C> SP> BC+SP> BC in the soils of sweet basil and marjoram plants.
• The decrease in available N was by 22, 26 and 29% for sweet basil soil and 19, 26 and 30% for marjoram soil for SP, BC+SP and BC, respectively, compared with the control.
• Available P was increased in the soil affected with salinity due to the application of BC, SP and BC+SP from 25.55 in the control treatment to 29.73, 39.51 and 44.66 mg kg-1 in sweet basil soil and from 24.2 in the control to 28.4, 38.8 and 44.6 mg kg-1 in marjoram soil.
• Except for BC application that slightly decreased available K from 408.5 mg kg-1 in the control of sweet basil soil to 406.2 mg kg-1 and from 408.0 mg kg-1 in the control of marjoram soil to 399.8 mg kg-1, all other treatments significantly increased available K.
• Both SP and BC+SP applications increased available K content in sweet basil soil by 27 and 72% and in marjoram soil by 20 and 69% compared with the control, respectively.
2-2 Effect of biochar (BC) and Spirulina algae extract (SP) on some plant growth parameters and nutrient content under water salinity stress:
2-2-1 Growth parameters
2-2-1-1 Sweet basil plants:
• The irrigation of sweet basil plants with saline water (control treatment) caused significant decreases in the plant height, leaf number, branch number, leave area, fresh weight, dry weight and total chlorophyll by 7, 35, 46 ,40, 45, 24 and 55%, respectively, compared to the fresh water control
• The addition of biochar for the plants irrigated with fresh water increased the previous parameters at rate 7, 2, 5, 4, 7, 33 and 55 %, respectively.
• The foliar application of SP significantly increased the plant height, leaf number, branch number, leaf area, fresh weight, dry weight and total chlorophyll from 71.4 cm, 167 L, 13.66 B, 17.8 cm, 141 g/pot, 21 g/pot and 44 mg/100g in the control irrigated with fresh water to 77.5 cm, 178 L, 15.66 B, 24.37 cm, 154 g/pot, 29 g/pot and 88 g/100g, respectively.
• The combination of BC +SP was the best and highest effective treatment that increased the last growth parameters by 22, 7, 20, 50, 12, 43 and 159 %, respectively, compared to fresh water control treatment.
• For the plants irrigated with saline water, the addition of BC and SP alone or together ameliorated the adverse effect caused by irrigation with saline water.
• The best effective treatment for enhancing all growth parameters against salt tolerance was the addition of BC+SP which significantly increased the last growth parameters by 8, 21, 73, 45, 8, 31 and 170 %, respectively, in comparison with saline water control.
• The addition of BC under salinity condition increased the measured growth parameters by 2, 0, 18, 8, 5, 13 and 65 %, respectively, in comparison with the saline water control treatment.
• SP also increased the last measured growth parameters by 5, 19, 45, 33, 4, 6 and 120 %, respectively, compared to saline water control.
2-2-1-2 Marjoram plants:
• Under saline stress, all discussed marjoram plant parameters were dramatically decreased compared with the normal irrigation water (fresh water) treatments.
• The irrigation of marjoram plants with saline water in the control treatment caused decrease in the plant height, fresh weight, dry weight and total chlorophyll by 27, 53, 57 and 71 %, respectively, compared to the fresh water control
• The best treatment that overcame the negative effect of salinity an also significantly increased all parameters under fresh water conditions was BC+SP treatment.
• Compared with the control of fresh, the combination of BC +SP increased the plant height, fresh weight, dry weight and total chlorophyll by 36, 49, 28 and 162% treatment.
• The addition of BC+SP under salinity condition increased the last growth parameters by 40, 91, 74 and 267%, respectively, in comparison with saline water control.
• The addition of biochar increased plant height, total chlorophyll, and fresh and dry weight at rate 8, 16, 9 and 93 %, respectively, compared with the control plants irrigated with fresh water.
• The foliar application of SP increased the plant height, total chlorophyll, fresh and dry weight by 21, 136, 22 and 17%, respectively, for marjoram plants irrigated with fresh water.
• For the plants irrigated with saline water, the addition of BC, SP alone or together ameliorated the adverse effect caused by irrigation with saline water.
• The addition of BC under salinity condition increased the measured growth parameters by 11, 100, 32 and 51%, respectively, in comparison with the saline water control treatment. SP also increased the last measured growth parameters at rate of 26, 192, 49 and 60%, respectively, compared to saline water control.
2-2-2 Nutrients content in plant tissues:
• The irrigation of plants with saline water always caused decreases in N, P, and K content in sweet basil and marjoram shoots.
• The N, P and K content in the control treatment of saline irrigation water was decreased by 38, 41, and 19%, for sweet basil and 56, 74 and 49% for marjoram plants respectively, compared to the control of the fresh water treatment.
The addition of BC, SP and SP+BC for fresh water treatments increased nutrients content by 34, 73 and 127% for N 174, 144 and 278% for P 42, 50 and 92% for K, respectively. There was also an increase in N, P and K content for marjoram by 14, 25 and 36% for N, 44, 66 and 102% for P and 22, 28 and 47% for K.
• The addition of BC, SP and SP+BC also increased the nutrients content of sweet basil irrigated with saline water by 66, 79, and 91% for N 75,75 and 113% for P 42, 47 and 61 for K, respectively.
• There was also an increase in nutrients content in marjoram plants with the addition of BC, SP and SP+BC by 99,105 and 112% for N, 69, 84 and 130% for P and 38, 56 and 92% for K.