الفهرس 
ACKNOWLEDGMENTOnly 14 pages are availabe for public view
 |  | from | 97 |  |  |
| | | from | 97 | | |
Abstract
This investigation was carried out during two successive winter seasons of 2014/2015 and 2015/2016 in the experimental farm, Agricultural Research Station of El-Kharga, the New Valley. The main objective of this invistigation was to study the effect of irrigation methods and water deficit on wheat productivity, irrigation water requirements and water use efficiency of wheat under New Valley conditions. The specific objectives were:
1. Evaluating the effect of irrigation regimes under flood, sprinkler and drip irrigation methods on growth and yield of wheat.
2. Measuring the water requirements and water productivity of wheat under different irrigation systems at the New Valley area.
3. Comparing between measured and estimated water requirements using different methods and produce the crop factor Kc at under the New Valley conditions.
4. Estimating the effect of irrigation systems and irrigation regimes on nutrients use efficiencies of wheat.
The experiment was laid out in strip plot design with four replications. Irrigation methods (flood, sprinkler and drip) were allocated horizontally; while, irrigation regimes (25, 50 and 75% soil moisture depletion, ASMD) were arranged vertically.
The obtained results could be summarized as follows:
5.1. Effect of Irrigation Methods and Regimes on Water Relations of Wheat:
5.1.1. Actual Evapotranspiration (ETa):
• Seasonal ETa mean values of both seasons were 384.3 and 406.2 mm under flooding irrigation method; 377.5 and 399.2 mm under sprinkler irrigation method; 371.1 and 393.6 m3 fed-1 under drip irrigation method in the first and second seasons, respectively.
• Seasonal evapotranspiration of wheat was increased as the available soil moisture increased in the root zone area. Where, the values of seasonal water consumptive use for wheat were 435.9, 369.2 and 327.8 mm in the first season and 461.6, 388.9 and 348.5 mm in the second season under irrigation at 25, 50 and 75% ASMD, respectively.
• The consumptive use of water by wheat was low at the early stage (initial) of growing season. This consumption increased to reach the peak values at midseason which coincides the critical period in the water demand by wheat. Then, the water consumption declined at the end of the growing season as crop became mature.
5.1.2. Reference Evapotranspiration (ETo):
• The estimated seasonal ETo values in both growing seasons followed a descending order of: Hargreaves-Samani> FAO-24 radiation> FAO-24 pan> christiansen Pan > Blaney-Criddle> Penman-Moteith> Priestley-Taylor> Makkink> Ritchie> Jensen-Haise.
• Seasonal ETo for wheat crop were 990.2, 785.9, 739.3, 739.4, 567.5, 469.4, 447.4, 380.3, 355.1 and 193.0 mm in the first growing season and 1012.1, 813.9, 806.7, 798.4, 597.7, 506.2, 461.6, 384.9, 366.4 and 198.4 mm in the second growing season as calculated by Hargreaves-Samani, FAO-24 radiation, FAO-24 pan, christiansen Pan, Blaney-Criddle, Penman-Moteith, Priestley-Taylor, Makkink, Ritchie, Jensen-Haise equations, respectively.
• The ratio between seasonal ETo of Priestley-Taylor and seasonal ETa was 0.99 and 1.01 in 1st and 2nd season, respectively. Penman-Moteith equation came in the second rank with the ratio of 0.95 and 0.93 in 1st and 2nd season compared with actual evapotranspiration, respectively. It is clear that the Priestley-Taylor and Penman-Moteith equations calculated ETo efficiently, however Priestley-Taylor equation was the most efficient in calculating ETo of wheat crop under the New Valley conditions.
5.1.3. Crop Coefficient (Kc):
• The average seasonal values of (Kc) were 0.94, 1.27, 1.00, 0.78, 0.46, 2.33, 0.57, 1.190.59 and 0.59 using Penman Monteith, Ritchie, Priestley-Taylor, Blaney-Criddle, Hargreaves-Samani, Jensen-Haise, FAO-24 radiation, Makkink, christiansen Pan and FAO-24 pan equations, respectively.
• The crop coefficient was low at the initial stage, and then a gradual increase was observed in crop coefficient. The crop coefficient reaches their peaks in medium growth stage. Then, the crop coefficient was decreased during the late season of plants.
5.1.4. Irrigation Water Applied (IWA) and Water Application Efficiency (WAE):
• The highest mean values of applied irrigation water were recorded by flood irrigation method (2761 and 2933 m3 fed-1) followed by sprinkler irrigation method (2151 and 2273 m3 fed-1). Meanwhile, drip irrigation method (1831 and 1931 m3 fed-1) in both seasons, respectively came in the third rank with lowest applied water.
• On the contrary, drip irrigation gave the highest mean value of application efficiency (85.09 and 85.60%). Meanwhile, sprinkler irrigation came in the second rank with 73.73 and 73.78%. Poor water application efficiency was observed by flood irrigation method (58.46 and 58.17%) in both seasons, respectively.
• Low water stress (25% ASMD) treatment gave the highest values followed by the moderate soil water stress (50% ASMD) treatment. Whereas, higher soil water stress conditions (75% ASMD) recorded the lowest mean values in both seasons, respectively.
• The interaction between irrigation methods and water deficit, the obtained results revealed that irrigation at 50% ASMD followed by 75% ASMD under drip irrigation method achieved the highest mean values of water application efficiency (86.97 and 87.19%) and (84.17 and 85.03%) in both seasons, respectively.
5.1.5. Water Productivity (WP):
• The CWP values under drip irrigation were 1.66 and 2.74 kg m-3 in the first season and 1.62 and 2.55 kg m-3 for grain and straw yields of wheat in the second season, respectively. The IWP followed the same trend; the values of IWP were 1.41 and 2.33 kg m-3 in the first season and 1.39 and 2.18 kg m-3 in the second season for grain and straw yields of wheat, respectively.
• The CWP and IWP values for grain yield are increased with increasing water stress up to 50% ASMD.
• The highest values of these traits were obtained under drip irrigation at 50% ASMD followed by 75% ASMD under the same irrigation method.
• Drip irrigation was gave the highest values of ECWP grain yield (6.22 and 6.07 LE m-3) and straw yield (3.01 and 2.80 LE m-3). The EIWP was followed the same trend, it is reach to 5.29 and 5.20 LE m-3 for grain yield; 2.56 and 2.40 LE m-3 for straw yield.
• The highest values of ECWP and EIWP were observed by 50% ASMD followed by 25% ASMD regime. Meanwhile, the lowest values were recorded by 75% ASMD regime.
• Applying 50% ASMD under drip irrigation method improved ECWP and EIWP (grain + straw) by 15.88 and 74.17% in the first season; 35.65 and 106.20% in the second season, respectively compared to flood irrigation method with 25% ASMD.
5.2. Effect of Irrigation Methods and Regimes on Growth, Yield and Its Components of Wheat:
5.2.1. Plant Height:
• Planting wheat under flood irrigation gave the tallest plants (87.97 and 89.99 cm) followed by drip irrigation (88.13 and 88.49 cm) without significant differences.
• The tallest wheat plants were obtained by irrigation at 25% ASMD.
• The highest value was obtained at 25% ASMD under drip irrigation.
5.2.2. Spikes Length:
• The longest spikes (11.02 and 11.03 cm) were observed under flooding irrigation followed by drip irrigation with 10.82 and 11.11 cm in the 1st and 2nd season, respectively.
• The 25% ASMD surpassed the other irrigation regimes in improving the spike length (11.42 and 11.58 cm) of wheat.
• The highest spike length value was obtained from treatments which irrigated at 25% ASMD under drip irrigation; the values were 12.06 and 12.01 cm in the 1st and 2nd season, respectively.
5.2.3. Number of Spikes per m2:
• It could be noticed that the number of spikes m-2 followed the order of: drip> flooding> sprinkler in the both seasons. The averages numbers of spikes m-2 were 345, 327 and 347 under flooding, sprinkler and drip irrigation, respectively in the 1st season. They were 346, 333 and 348 spikes m-2 under the same respective irrigation methods in the 2nd season.
• Irrigated wheat plant at 25% ASMD recorded more spikes per square meter (355 and 357 spikes m-2) than the other irrigation regimes.
• Irrigation wheat plants at 25% ASMD by drip recorded the highest values of number of spikes m-2 followed by flood irrigation system with the same irrigation regime compared with other interaction treatments.
5.2.4. Number of Grains per Spike:
• The highest values of grains per spike were 53.49 and 53.08 under drip irrigation in both seasons, followed by flood irrigation with 51.21 and 52.27 grains per spike.
• The highest number of grains per spike (55.59 and 56.38 grains spike-1) was obtained by irrigating wheat plants at 25% ASMD in the two seasons.
• The maximum values of grains per spike (63.53 and 60.52 grains spike-1) were recorded by irrigating wheat plants at 25% ASMD under drip irrigation followed by flood irrigation with the same irrigation regime.
5.2.5. Grains Weight per Spike:
• The heaviest spikes (1.49 and 1.44 g) were observed under flood irrigation followed drip irrigation (1.39 and 1.52) without significant differences.
• Irrigating wheat plants at 25% ASMD regime caused significant increase in this trait compared to the other irrigation regimes.
• The interaction effect showed that irrigating wheat plants at 25 or 50% ASMD under drip irrigation as well as at 25% ASMD under flood irrigation produced heaviest spikes without significant difference.
5.2.6. Weight of 1000-Grains:
• Weight of 1000-grains followed the order of flooding> drip> sprinkler in both season. The heaviest (35.40 and 34.81 g) and lightest (33.14 and 34.77 g) grains were recorded under sprikler irrigation methods, respectively.
• Irrigation of wheat plants at 50% ASMD was increased 1000- grain weight compared to irrigation of wheat plants at 25 or 75% ASMD regimes.
• Irrigated wheat plants at 50% ASMD under drip gave the heaviest (36.66 and 36.38 g) weight of 1000-grains as compared with other interaction treatments in both seasons.
5.2.7. Biological Yield per Feddan:
• It was noticed that the obtained biological yield followed the order of drip> sprinkler > flooding as average of two growing seasons.
• The highest significant biological yield was recorded with 25% ASMD regime (6476.12 and 6705.63 kg/fed) compared with 75% ASMD regime (3981.20 and 4122.30 kg fed-1) in 2014/15 and 2015/16 seasons, respectively.
• Using drip irrigation at 25% ASMD regime gave the highest mean values of biological yield (7970 and 7364 kg fed-1).
5.2.8. Grain Yield per Feddan:
• Drip-irrigated wheat plants registered the highest mean values of grain yield of wheat (2583 and 2677 kg fed-1) in both seasons, respectively.
• The averages of grain yield were 2825, 2493 and 1678 kg fed-1 in the first season; 2609, 2443 and 1894 kg fed-1 in the second season under 25, 50 and 75% ASMD.
• Using drip irrigation at 25% ASMD regime gave the highest mean values of grain yield (3067 and 3085 kg fed-1).
5.2.9. Straw Yield per Feddan:
• The averages of wheat straw yield over the two seasons were 3782, 3637 and 4263 kg fed-1 in the first season; 3769, 3872 and 4211 kg fed-1 in the second season under flood, sprinkler and drip irrigation methods, respectively.
• There was a gradual decrease of straw yield as the ASMD increased from 25% to 75 %. Where, irrigation of wheat plants at 25% ASMD was surpassed over other irrigation regimes in both seasons.
• Irrigating wheat plants at 25% ASMD under flood irrigation gave the highest values of straw yield followed by drip or sprinkler irrigation methods with the same irrigation regime.
5.2.10. Harvest Index:
• Irrigation methods had insignificant effect on harvest index. Sprinkler irrigation method was surpassed over drip and flood in the first season meanwhile, drip irrigation was the best in the second season.
• Harvest index was insignificantly affected by irrigation regimes in both seasons. Irrigation at 25% ASMD recoded the highest values of harvest index compared to irrigation at 50 or 75% ASMD.
• The interaction effect between irrigation methods irrigation regimes has insignificant effect on harvest index in both studied seasons. Generally, irrigating wheat plants at 75% ASMD under sprinkler irrigation was superior to all interaction treatments in the 1st season. Meanwhile, using drip irrigation at 25% ASMD gave the highest values of harvest index in the 2nd season.
5.3. Nutrient Use Efficincies: • Drip irrigation recorded the highest values of N (25.83 and 26.77), P (86.08 and 89.25) and K (107.61 and 111.56) use efficiencies.
• Plants irrigated at 25% ASMD gave the highest efficiencies of N, P and K (28.25 and 26.09; 94.17 and 86.96; 117.11 and 108.70) as compared with all other irrigation regimes in 2014/15 and 2015/16 seasons, respectively.
• Irrigating wheat plants at 25% ASMD under drip irrigation gave the highest NUE (30.67 and 30.85), PUE (102.22 and 102.85) and KUE (127.77 and 128.56) compared with the other interaction treatments in both seasons, respectively .