الفهرس 
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Abstract
The present study was conducted to investigate the effect of using drainage water in different combination with normal water (mixing and alternatives) on cotton growth, yield, yield components and fiber quality properties besides studying the possibility of using nitrogen fertilizer to minimize the harmful effect of low quality water on cotton growth, yield and fiber quality properties.
This study was carried out at the experimental farm of faculty of agriculture, el-Fayoum University at Dar El-Ramad, during 2005and 2006 seasons. Giza 90(G 83 x Dendera) as Upper and Middle Egypt long staple cotton was used in this study. Five irrigation treatments represent different mixtures of Fresh water and drainage water besides, nitrate ammonium and urea nitrogen fertilizers under three rates 60, 70, and 80 kg of N were used .Planting dates was in 14 Marsh in the two seasons.
The experimental work included two separate experiments, in the first experiment, nitrogen fertilizer application was done according to the common way, being applied at two equal doses, the first was side dressed immediately before the second irrigation and after thinning, the second dose was side dressed before the third irrigation. In the second experiment nitrogen fertilizer was applied at equal frequent small doses before each irrigation by mixed and drainage water up to the last irrigation as a tool to overcome the harmful effect of this low quality water on cotton growth, yield and quality.
Each experiment was laid out in split - split plot at complete randomized blocks design, with three replications. The main plots were assigned for irrigation treatments, while the sub- plots for the tow types of nitrogen fertilizer. Sub-sub plots were assigned for the three rates of each N fertilizer. Plot size was (9.0m x 3.0m), and consists of three ridges (4m x60cm) apart. Hills spaced at (20cm), each hill was thinned out to only two plants, after thinning ten guarded plants were assigned at random from the middle one of the three rows in each plot for the purpose of field and growth. While the seed and lint cotton of the whole plot was used to determine yield and yield components for the different treatments. Lint cotton of each plot was used for fiber testing, as well as, to be spun into 60 carded yarns in the experimental spinning mill of Cotton Res, Institute, to determine yarn strength for the different treatments. Fiber and yarn tests were conducted at the labs of CRI. At constant relative humidity of 65%RH (± 2) and temperature of 200C (± 1).Test specimens of Giza 90 variety were taken from the petiole and leaf blade corresponding the median internodes of the main stem as well as the stem and root. Analysis of variance and LSD test at (0.05%) level of significance were carried out to compare the different means.
I-Effect of irrigation by lowquality water on cotton growth, yield and quality:-
A) Growth characters:
1- Plant height (cm). plant height was decreased as the amount of drainage water (low quality Water) increased whether by its percentage in irrigation water and/or by the times of using this low quality water in irrigation. The highest reduction in cotton plant height after 70 days and 100 days post planting was obtained from (75% D / 25 % F) irrigation treatment in 2005 and 2006 seasons. (50%D / 50%F) and the treatment of irrigating by fresh and drainage water alternatively showed nearly similar and moderate reduction in cotton plant height. Using two irrigations of river water followed by once of drainage water showed the lowest reduction in the plant height in the two growth stages over the two seasons.
Amonium nitrate fertilizer showed higher plant height means at 70 days and 100 days after planting than urea fertilizer under all the irrigation treatments over the two seasons.
The lowest plant hight at 70 days and 100 days after planting was obtained from the treatment. (75D/25F) irrigation under (60 kg N) from urea form in both 2005 and 2006 seasons while the highest plant hight in the two growing stages was obatined in the two seasons from the control treatement fertilized with nitrate ammonium at (80 kg N) rate. Nitrate ammonium seemed to be effective and produced taller cotton plants as the drainage water (salinity) increased in the irrigation water compared to urea N source while both of two fertilizer forms did not show significant differences in plant hight when the fresh water amount increased in the irrigation water.
2- Leaf Area (cm²). leaf area after 70 days and 100 days post planting was decreased significantly as the amount of Drainage water increased. The highest reduction in cotton leaf area was obtained from (75D/25F) irrigation treatment in 2005 and 2006 seasons as compared to the Control treatment (river water). Using two irrigations of river water followed by once of drainage water showed the lowest reduction in the leaf area in the two growth stages over the two seasons 2005 and 2006 compared to the control and the other irrigation treatments.
Amonium nitrate fertilizer showed higher leaf area means than urea fertilizer at 70 days and 100 days after planting under all the irrigation treatments over the two seasons.
The lowest leaf area at 70 days and 100 days after planting was obtained from the treatment. (75D/25F) irrigation under (60 kg N) from urea in both 2005 and 2006 seasons, while the highest leaf area in the two growing stages was obatined in the two seasons from the control treatement fertilized by nitrate ammonium at (80 kg N) rate. Nitrate ammonium seemed to be more effective and produced higher cotton leaf area as the drainage water (salinity) increased in the irrigation water compared to urea N source while both of the two fertilizer forms did not show significant differences in leaf area when the fresh water amount increased in the irrigation water.
3- Plant Dray Weight (gm). plant dry weight after 70 days and 100 days post planting was decreased significantly as the amount of drainage water increased in irrigation water. The highest reduction in cotton plant dray weight was obtained from (75%D / 25% F) irrigation treatment in 2005 and 2006 seasons as compared to the Control treatment (river water). Using two irrigations of river water followed by once of drainage water showed the lowest reduction in the plant dray weight in the two growth stages over the two seasons 2005 and 2006 compared to the control and the other irrigation treatments.
Amonium nitrate fertilizer showed higher plant dray weight means at 70 days and 100 days after planting than urea fertilizer under all the irrigations treatments over the two seasons.
The lowest plant dray weight at 70 days and 100 days after planting was obtained from the treatment. (75D/25F) irrigation under (60 kg N) from urea form in both 2005 and 2006 seasons while the highest plant dray weight in the two growing stages was obatined in the two seasons from the control treatement fertilized with nitrate ammonium at (80 kg N) rate.
4- Number Of Fruiting Branches. the results indicated that number of fruiting branches was decreased as the amount of drainage water increased in irrigation water. Irrigation treatments showed significant effect on cotton fruiting branches number at both seasons. The highest reduction in cotton fruiting branches number was obtained from (75%D / 25% F) irrigation treatment which averaged 7.3 and 9.2 fruiting branches in 2005 and 2006 seasons respectively compared to the Control treatment (river water) which averaged 8.9 – 14.0 fruiting branches in 2005 and 2006 seasons respectively. (50%D / 50%F) and the treatment of irrigating by fresh and drainage water alternatively showed nearly similar and moderate reduction in cotton fruiting branches. Irrigation treatment of using two irrigations of river water followed by once of drainage water showed the lowest reduction in the fruiting branches in the two growth stages over the two seasons 2005 and 2006 compared to the control and the other irrigation treatments.
Amonium nitrate fertilizer showed higher fruiting branches means than urea under all the irrigation treatments over the two seasons.
The lowest fruiting branches number was obtained from the irrigation treatment. (75D/25F) under (60 kg N) from urea in both 2005 and 2006 seasons while the highest fruiting branches number in the two growing stages was obatined in the seasons from the control treatement fertilized by nitrate ammonium at (80 kg N) rate. Treatment (2F/1D, 70 and 80 kg N) from nitrate ammonium showed relatively higher fruiting branches number than the other treatments and very close to the control treatment over the two seasons.
B) Yield and yield component characters:
1- number of total and open bolls/plant. number of total and open bolls/plant were decreased significantly as the amount of drainage water increased in irrigation water. The lowest number of total bolls and open bolls/plant was obtained from (75%D/25%F) irrigation treatment, means for this treatment were (15.4 and 18.7) for total bolls/plant in 2005 and 2006 respectively and (12.0 and 15.7) for number of open bolls/plant for the same irrigation treatment in the two seasons respectively. The highest number of total bolls /plant and open boll number/plant was obtained from the control treatment (100% fresh water). Means were (18.0 and 28.3) for total bolls/plant in 2005 and 2006 seasons respectively and (14.9 and 21.0) for open bolls number/plant in the two seasons respectively.
(60 kg and 70 kg N) rates don’t show significant differences in both of total boll number/plant and open boll number/plant in the two seasons, as well as being not significant between (70 kg N and 80 kg N) rates in the two seasons. Combination of irrigation treatment (2F/1D), (70 and 80 kg N) from nitrate ammonium showed relatively higher number of total and open bolls/plant than the other treatments and very close to the control treatment over the two growing seasons.
2-Seed and Lint Cotton Yield Kentar/Faddan. both of seed and lint cotton Yield were decreased significantly as the amount of drainage water increased in irrigation water. The lowest seed and lint cotton yield was obtained from (75%D/25%F) irrigation treatment. Means for this treatment were (6.8 and 8.9 ken/fed.) for seed and lint Cotton yield in 2005 and 2006 respectively while being (7.6 and 10.2 ken/fed.) for lint Cotton yield in 2005 and 2006 respectively. The highest seed and Lint Cotton yield was obtained from the control treatment (100% fresh water). Means were (9.0 and 12.0 ken/fed) for seed Cotton yield in 2005 and 2006 seasons respectively and (10.2 and 14.3ken/fed) for lint Cotton yield in the two seasons respectively.
(60 kg and 70 kg N) rates don’t show significant differences in both of seed and lint cotton yield in the two seasons, as well as being not significant between (70 kg N and 80 kg N) rates in the two seasons.
With regard to the effect of the interaction between irrigation treatment, fertilizer forms and rates. The lowest seed and lint cotton yield was obtained in 2005 from the combination (75D/25F) irrigation treatment under (60 kg N) urea nitrogen while obtained in 2006 from the combination (75D/25F) irrigation treatment, (60 kg N) from nitrate and urea. The highest seed and lint cotton yield was obtained from the control treatment (100% fresh water) with (80 kg) nitrate nitrogen in both 2005 and 2006 seasons. Combination of irrigation treatment (2F/1D), (70 and 80 kg N) from nitrate ammonium showed relatively high seed and lint cotton yield than the other treatments and very close to the control treatment over the two growing seasons.
3-Seed Index ( gm ) and Lint Percentage %: both characters were decreased significantly as the amount of drainage water increased in irrigation water. The lowest seed index and lint percentage was obtained from (75%D/25%F) irrigation treatment, means for this treatment were (8.6 and 8.7 gm) for seed index in 2005 and 2006 respectively and (35.2 and 36.5 %) for lint percentage in the two seasons respectively, while the Highest seed index and lint percentage was obtained from the control treatment (100% fresh water). Means were (9.7 and 10.4 gm) for seed index in 2005 and 2006 seasons respectively and (36.2 and 37.5 %) for lint percentage in both seasons respectively.
Nitrate ammonium fertilizer showed slightly higher means of seed index and lint percentage than urea fertilizer means, while seed index and lint % increased slightly as the rate of N fertilizer increased.
With regard to the effect of the interaction between irrigation treatment, fertilizer forms and rates, The lowest seed index and lint percentage was obtained in 2005 from the combination (75D/25F]) irrigation treatment under (60 kg N) urea and / or nitrate nitrogen. The highest seed index and lint percentage was obtained from the control treatment (100% fresh water) with (80 kg) nitrate nitrogen in both 2005 and 2006 seasons.
4-Boll Weight (gm). was decreased significantly as the amount of drainage water increased in irrigation water. The lowest mean of boll weight (gm) was obtained from (75%D/25%F) irrigation treatment, means for this treatment were (1.96 and 2.16 gm) in 2005 and 2006 respectively, while the highest boll weight (gm) was obtained from the control treatment (100% fresh water) being (2.47 and 2.62 gm) in both seasons respectively.
Nitrate ammonium fertilizer showed slightly higher means of boll weight (gm) than urea fertilizer.
Treatment (60 kg and 70 kg N) rates did not show significant differences in boll weight (gm) in the two seasons and not significant between (70 kg N and 80 kg N) rates in the two seasons.
With regard to the effect of the interaction between irrigation treatment, fertilizer forms and rates. The lowest boll weight (gm) was obtained in 2005 from the combination (75D/25F]) irrigation treatment under (60 kg N) urea nitrogen, while the highest boll weight (gm) was obtained from the control treatment (100% fresh water) with (80 kg) nitrate nitrogen in both seasons. Combination of irrigation treatment (2F/1D), (70 and 80 kg N) from nitrate ammonium showed relatively higher boll weight (gm) than the other treatments and very close to the control treatment over the two growing seasons.
C) Fiber and yarn quality characters:
1-fiber length (upper half mean length mm). irrigation treatments decreased significantly fiber length. The decrease in fiber length increased as the percentage of the drainage water increased in irrigation water. The lowest means of fiber length was obtained from (75%D/25%F) irrigation treatment being (28.7 and 30.0 mm) in 2005 and 2006 seasons respectively, while the highest means of fiber length was shown by the control fresh water treatment being (30.3 and 30.9 mm) in the two seasons respectively. The other three irrigation treatments did not show significant difference between their means of fiber length being about (29.4 mm) in 2005 and (30.4 mm) in 2006.
Nitrogen fertilizer forms and levels did not affect fiber length significantly. All the interaction between irrigation treatments and nitrogen fertilizer forms and levels were not significant.
2- Fiber length uniformity index %: irrigation treatments, nitrogen fertilizer forms, and rates and their interactions did not affect significantly fiber length uniformity index except the effect of irrigation treatments on fiber length uniformity which was significant in 2005 season.
Nitrogen fertilizer forms and rates did not show significant effect on fiber length uniformity. All the interactions between irrigation and fertilizer treatments showed insignificant effect on fiber length uniformity
3- Fiber strength (g/tex) and Elongation (%) . fiber strength decreased significantly as the percentage of low quality water increased in irrigation water. The lowest means of fiber strength (g/tex) was obtained from (75%D/25%F) irrigation treatment being, (33.2 and 33.3 g/tex) in 2005 and 2006 seasons respectively, while the highest means of Fiber strength (g/tex) was shown by the control fresh water treatment being (34.5 and 35.2 g/tex) in the two seasons respectively.
Nitrogen fertilizer forms and rates did not affect fiber strength (g/tex) significantly.
Irrigation treatments, Nitrogen fertilizer forms and rates did not affect significantly fiber elongation.
5-Micronaire value (Mic). irrigation treatments decreased significantly micronaire value. The lowest means of micronaire value was obtained from (75%D/25%F) irrigation treatment being (3.76 and 3.77) in 2005 and 2006 seasons respectively while the highest means of micronaire value was shown by the control fresh water treatment being (3.88 and 3.93) in the two seasons respectively.
Nitrogen fertilizer forms and levels did not affect micronaire value significantly.
6- Matutity ratio % (MR). fiber maturity decreased significantly as the percentage of drainage water increased in irrigation water. The lowest means of maturity ratio was obtained from (75%D/25%F) irrigation treatment being (0.82 and 0.83 %) in 2005 and 2006 seasons respectively while the highest means of Maturity ratio was shown by the control fresh water treatment being (0.87 and 0.89 %) in the two seasons respectively.
Nitrogen fertilizer forms and levels did not affect Maturity ratio % significantly.
7- Reflectance degree (Rd )% (fiber color). irrigation treatments decreased significantly Reflectance degree of Giza 90 cotton variety. The highest means of Reflectance degree was shown by the control fresh water treatment being (64.4 and 65.2) in the two seasons respectively. While the lowest means of Reflectance degree was obtained from (75%D/25%F) irrigation treatment being (62.8 and 63.6) in 2005 and 2006 season’s respectively. Nitrogen fertilizer forms and levels did not affect Reflectance degree significantly.
8- Lea strength (g/tex). irrigation treatments decreased significantly Lea strength of Giza 90 cotton variety. The lowest means of lea strength was obtained from (75%D/25%F) irrigation treatment being (1780 and 1830) in 2005 and 2006 seasons respectively while the highest means of lea strength was shown by the control fresh water treatment being (1950 and 1980) in the two seasons respectively. Nitrogen fertilizer forms and levels affected on Lea strength significantly.
9-Reversals number: irrigation treatments decreased significantly Reversal number. The highest means of Reversal number was shown by the control fresh water treatment being (30.7 and 31.3) in the two seasons respectively, while the lowest means of Reversals number was obtained from (75%D/25%F) irrigation treatment being (28.2 and 27.8) in 2005 and 2006 seasons respectively.
Nitrogen fertilizer forms and levels affect significantly reversals number significantly. Nitrate and urea fertilizers averaged (29.6 and 28.4) in 2005 and averaged (30.2 and 28.9) in 2006 respectively,.
10- Convolutions number: irrigation treatments and nitrogen fertilizer forms and rates decreased significantly convolutions number. The lowest means of Convolutions number was obtained from (75%D/25%F) irrigation treatment being (10.5 and 11.3) in 2005 and 2006 seasons respectively while the highest means of Convolutions number was shown by the control fresh water treatment being (12.8 and 13.5) in the two seasons respectively.
Nitrate and urea fertilizers averaged (12.6 and 11.7) in 2005 and averaged (13.1 and 12.4) in 2006 respectively,
II- Using nitrogen fertilizers as a tool to overcome the harmful effect of low quality water on cotton growth, yield and quality.
Adding nitrogen fertilizer in low rates just before irrigation by drainage low quality water enabled to overcome the harmful effect of this low quality water on cotton growth, yield and quality. The obtained results of this work could be summarized as follows:-
A- improvement and changes in growth measurements:
1- Plant height (cm): plant height At 70 days and 100 days after planting improved when applying N fertilizer in small doses before irrigation by low quality drainage water by about (20-30 %), as compared to the common method of applying N fertilizer in two doses. Means of plant high after 70 days were (39.1, 41.9, 40.0, 46.4 and 54.0 cm) in 2005 and (44.4, 48.5, 46.6, 52.0 and 54.5 cm) in 2006 season for the five irrigation treatments respectively. Plant height after 100 days showed the same trend.
Nitrate fertilizer showed slightly higher plant heights means than urea whether at 70 days or at 100 days after planting.
Regarding the interaction between irrigation treatments, nitrogen fertilizer forms and rates, the highest values of plant height in the two ages over the two seasons was obtained from the control treatment (fresh water) using nitrate fertilizer at (80kgN) level while the lowest one was obtained from (75%D/25%F) using urea at (60kg) N rate.
2- Leaf Area (cm²). leaf area at 70 days and 100 days after planting improved when applying N fertilizer in small doses before irrigation by low quality drainage water by about (10-20 %), as compared to the common method of applying N fertilizer in two doses. The recorded means of Leaf area after 70 days were (10.4, 11.1, 11.12.1 and 12.7 cm²) in 2005 and (11.5, 12.2, 11.8, 12.7 and 12.9 cm²) in 2006 for the five irrigation treatments respectively. Leaf area after 100 days showed the same trend.
Nitrate fertilizer showed slightly higher Leaf area means than urea whether at 70 days or at 100 days after planting.
Interaction between irrigation treatments, nitrogen fertilizer forms and levels showed that the highest values of Leaf area in the two ages over the two seasons was obtained from the control treatment (fresh water) using nitrate fertilizer at (80kgN) level while the lowest one was obtained from (75%D/25%F) using urea at (60kg)N rate.
3- Plant Dray Weight (gm). plant dry weight at 70 days and 100 days after planting improved when using the mentioned technique by about (20-30 %) than applying N fertilizer in two doses. The records of plant dray weight (gm) after 70 days were (21.6, 22.3, 22.1, 23.9 and 24.5 gm) and (22.4, 23.8, 23.0, 24.8 and 27.1 gm) for the five irrigation treatments respectively in 2005 and 2006 seasons. Plant dray weight after 100 days showed the same trend.
Nitrate fertilizer showed higher plant dray weight means than urea whether at 70 days or at 100 days after planting. Interaction between irrigation treatments, nitrogen fertilizer forms and rates showed that the highest values of plant dray weight in the two ages over the two seasons was obtained from the control treatment (fresh water) using nitrate fertilizer at (80kg N) level while the lowest one was obtained from (75%D/25%F) using urea at (60kg) N level.
4- Number of Fruiting Branches: number of Fruiting Branches at harvesting improved when using the mentioned techniques by about (10-20 %) than obtained from applying N fertilizer in two doses. the highest means of fruiting branches was shown by the control fresh water treatment being (1.4 and 17.8) in the two seasons respectively. While the lowest means was obtained from (75%D/25%F) irrigation treatment being (9.1 and 11.6) in 2005 and 2006 seasons respectively.
Nitrate fertilizer showed slightly higher cotton fruiting branches means than urea in both seasons.
Interaction between irrigation treatments, nitrogen fertilizer forms and rates showed that the highest values of fruiting branches number was obtained in the two seasons from the control treatment (fresh water) using nitrate fertilizer at (80kg N) level while the lowest one was obtained from (75%D/25%F) using urea at (60kg) N rate.
B-Improvement in cotton yield and yield components:
1- number of total and open bolls/plant. adding nitrogen fertilizer in small doses before using low quality drainage water and its mixtures improved and increased the number of total and open bolls. The increase in boll number ranged from (10-20%) compared to the method of adding N fertilizer in two doses only. Means of number of total bolls for the irrigation treatments ranged from (19.7) for (75%D/25%F) to (23.4 boll) for the control fresh water treatment in 2005 while ranged in 2006 from (22.8 to 35.7) for the two treatments respectively.
Nitrate fertilizer showed slightly higher number of total and open bolls means than urea in both season.
Regarding irrigation treatments × N fertilizer form × N fertilizer rate interaction the results indicated that the number of total and open bolls was increased even in the control treatment irrigated by 100% fresh water but this increase was higher in case of using drainage water and differed from rate to rate of N fertilizer and between the two forms of fertilizer as well.
2-Seedand Lint CottonYield (Kentar/Faddan): seed and lint cotton yield increased by (10-20%) compared to the method of adding N fertilizer in two doses only. Means of seed cotton yield for the irrigation treatments ranged from (8.3) for (75%D/25%F) to (11.3) ken/fed for the control fresh water treatment in 2005 while ranged in 2006 from (11.3 to 14.9ken/fed) for the two treatments respectively. Lint cotton yield ranged from (9.3to12.9ken/fed) for the two irrigation treatments in 2005 while ranged from (13.2 to 18.1ken/fed) in 2006.
No big difference was found between urea and nitrate as well as between the three rates of them regarding their effect on seed and lint cotton yield.
Concerning irrigation × N fertilizer form × N fertilizer rate interaction, seed and lint cotton yield was increased even in the control treatment irrigated by 100% fresh water, however this increase was higher in case of using drainage water and differed from level to level of N fertilizer and between the two forms of fertilizer as well.
3- Seed Index (gm) andLint Percentage %: adding nitrogen fertilizer in small doses before using drainage water improved and increased seed index and lint % in 2005 and 2006 seasons compared to the method of adding N fertilizer in two doses only. Means of seed index for the irrigation treatments ranged from 8.2gm for (75%D/25%F) to 9.3gm for the control fresh water treatment in 2005 while ranged in 2006 from 10.5 to 11.5gm for the two treatments respectively. Lint % ranged from 35.7 to 36.5 % for the previous two irrigation treatments in 2005 while ranged from 37.8 to 40.3 % in 2006.
No big difference between urea and nitrate as well as between the three rates of them regarding their effect on seed index and Lint (%).
4-Boll Weight (gm). adding nitrogen fertilizer in small doses before using drainage water improved and increased significantly boll weight (gm). Means of boll weight for the irrigation treatments ranged from 2.16gm for (75%D/25%F) to 2.38gm for the control fresh water treatment in 2005 while ranged in 2006 from (2.72 to 2.96 gm) for the two treatments respectively.
No big difference between urea and nitrate as well as between the three levels of them regarding their effect on boll weight. Regarding irrigation treatments × N fertilizer form × N fertilizer level interaction, boll weight was increased even in the control treatment irrigated by 100% fresh water but this increase was higher in case of using drainage water and differed from level to level of N fertilizer and between the two forms of N fertilizer as well.
C- Improvement in cotton quality properties:
1-fiber length (mm). adding nitrogen fertilizer in small doses before using low quality drainage water and its mixtures improved and increased the fiber length (mm). Means of fiber length (mm) for the irrigation treatments ranged from (29.7mm) for (75%D/25%F) to (31.0mm) for the control fresh water treatment in 2005 while ranged in 2006 from (31.2 to 31.8mm) for the two treatments respectively.
No big difference between urea and nitrate as well as between the three levels of them regarding their effect on fiber length (mm) although of its statistical significance.
Irrigation treatments × N fertilizer form × N fertilizer level interaction indicated that fiber length (mm) was increased even in the control treatment irrigated by (100% fresh water) but this increase was higher in case of using drainage water .
2- Fiber length uniformity index %: adding N fertilizer in small doses before irrigation by drainage water improved length uniformity to be very close to what obtained from the control treatment. Means of Fiber length uniformity for the irrigation treatments ranged from 85.5 % to 85.7 % in 2005 while ranged in 2006 from 86.0 to 86.9 %.
The effect of N fertilizer forms and levels was marginal although of its statistical significance in some cases.
3-Fiber strength (g/tex). adding nitrogen fertilizer in small doses before using drainage water improved and increased the Fiber strength (g/tex). Means of Fiber strength for the irrigation treatments ranged from 35.3 to (35.5 g/tex for in 2005 while ranged in 2006 from 36.9 to 37.1 g/tex.
Regarding irrigation treatments × N fertilizer form × N fertilizer level interaction, Fiber strength was increased even in the control treatment irrigated by (100% fresh water) but this increase was higher in case of using drainage water and differed from level to level of N fertilizer and between the two forms of fertilizer.
4-Elongation (%) . adding N fertilizer in small doses just before irrigation by drainage water improved fiber elongation and led to insignificant differences between the different treatments and the control.
5-Micronaire reading and Maturity ratio (%). the results indicated that adding nitrogen fertilizer in small doses before using drainage water improved Micronaire value (fiber maturity) to be very close to Micronaire value of the control irrigated by fresh water.
Means of Micronaire value for the irrigation treatments ranged from 4.16 to 4.18 in 2005 while ranged in 2006 from 4.33 to 4.43 with no significance between treatments.
Means of Maturity ratio (%) for the irrigation treatments ranged from 0.92% to 0.93% for the control fresh water treatment in 2005 while ranged in 2006 from 0.95 to 0.97% for the two treatments respectively.
N fertilizer forms an rates showed marginal effect on micronaire value and fiber maturity although of its statistical significance.
6- Fiber color -Reflectance degree (Rd %): color Rd% improved by about (10-20%) when using the method of adding nitrogen fertilizer in small doses just before irrigating by drainage water, compared to the method of adding N fertilizer in two doses only. Means of Reflectance degree (%) for the irrigation treatments ranged from 66.1 to 67.1% in 2005 while ranged in 2006 from 67.8 to 68.1%.
No big difference was found between urea and nitrate as well as between the three levels of them regarding their effect on Reflectance degree (%).
7-Lea strength (g/tex) . adding nitrogen fertilizer in small doses before using drainage water improved lea strength in 2005 and 2006 seasons. Means of lea strength for the irrigation treatments ranged from (1975) for (75%D/25%F) to (2030) for the control fresh water treatment in 2005 while ranged in 2006 from (2145 to 2220) for the two treatments respectively.
Nitrogen fertilizer forms and rates showed no big difference between urea and nitrate as well as between the three levels of them although of its statistical significance.
In regard to irrigation treatments × N fertilizer form × N fertilizer level interaction, lea strength was increased even in the control treatment irrigated by 100% fresh water, but this increase was higher in case of using drainage water and differed from level to level of N fertilizer and between the two forms of fertilizer as will.
8- Reversals number: adding N fertilizer in small doses before using drainage water led to insignificant differences between treatments. Means of Reversals number for the irrigation treatments were around 30.5 in 2005 while ranged in 2006 from 35.5 to 36.0.
Although the effect of nitrogen fertilizer forms and levels on Reversals number reached the level of significance statistically but these differences were not so big in the two seasons.
9-Convolutions number : adding nitrogen fertilizer in small doses before using low quality drainage water and its mixtures improved convolutions number of the cotton irrigated by drainage water to be closer to what obtained from the control treatment. Means of convolutions number for the irrigation treatments were around 12 and 15 in 2005 and 2006 respectively
Nitrogen fertilizer forms and levels showed no big effect on convolutions number although this effect reached the level of significance statistically.
III- Histological studies:
The histological study has been carried out on transverse sections of leaf, stem and root of cotton plant, to fined out and specify any alteration could be taken place in theses part due to the different irrigation and nitrogen fertilizer treatments.
A) - Leaf anatomy. using drainage water in irrigation led to a clear decrease in the thickness of midven, moreover decreased the thickness of the upper and lower collenchymas tissue, mean vascular bundle, size of xylem and phloem tissue, thickness of xylem rows and diameter of widest xylem vessel and lamina tissue, epidermis layers (upper, lower), palisade and spongy tissue as compared to the control irrigated by normal river water.
B)-The main stem anatomy. using drainage water in irrigation led to a clear decrease Diameter of the whole section, moreover decreased the thickness of the epidermal layer followed by the thickness of cortex, the thickness of phloem region, the thickness of vascular cambium region, the thickness of xylem region, the diameter of widest xylem vessel and the thickness of pith layer as compared to the control irrigated by normal river water. The amount of this decrease became higher as the amount of drainage water increased in the irrigation water.
C)-The main Root anatomy. using drainage water in irrigation led to a clear decrease Diameter of whole section, more over decreased the thickness of the epidermis and endodermis tissues, the thickness of cortex region, the thickness of phloem region, the thickness of pricycle region, the thickness of xylem region and the diameter of widest xylem vessel as compared to the control irrigated by normal river water.
*Changes in leaf, steam and root anatomy caused by frequent small doses of nitrogen fertilizer to overcome the harmful effect of low quality water on cotton growth:
The modified method of nitrogen fertilizer application resulted in (10-20 %) increase in the size of different tissues of cotton leaf, stem and root under all the irrigation treatments even in the control treatments irrigated by normal river water. However the increase in the size of different leaf, stem and roots tissues became higher as the drainage water amount increased in the irrigation water.