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Abstract
Three experiments were carried out at The Experimental Farm, of the Faculty of Environmental Agricultural Sciences, El-Arish, Suez Canal University, during two successive seasons, 2004/2005 and 2005/2006. The first and the second experiments, aimed to study the effect of irrigation intervals and plant density (distance between irrigation laterals) on sugar beet (Beta vulgaris L. cv. LP12) and fodder beet (Beta vulgaris L. cv. VÖrÖshenger). The third experiment aimed also, to study the effect of irrigation intervals and plant density (distance between rows), on wheat (Triticum aestivum vulgare cv. Sakha 93).
Treatments:
The first and second experiments were assigned for cultivating sugar and fodder beet plants. Each experiment included 9 treatments, for the interaction between 3, 5 and 7 days irrigation intervals, and 40, 50 and 60 cm distances, between drip lateral lines. Each treatment plot consisted of 3 lateral lines, each was 10 m long. The treatments plot area was either 12, 15 or 18 m2. Seeds of sugar or fodder beet plants were sown on the 1st of October in two successive seasons, 2004/2005 and 2005/2006, at a rate of 3 kg/fed. Plants were thinned to 2 plants/hill, on 30/10 and thinned again to 1 plant/hill, on 14/11. The irrigation water was saline ground water (3648 ppm) pumped from a local well. After a 60 days pretreatment period, irrigation intervals treatments started for all plots on 30/11. For the 3 days irrigation interval treatment, it ended on 25/4. The last irrigation took place on 23/4. For the 5 days irrigation interval treatment, it ended on 23/4. The last irrigation occurred on 19/4. For the 7 days irrigation interval treatment, it ended on 25/4. The last irrigation occurred on 19/4.
The third experiment was assigned for cultivating wheat. It included 9 treatments, for the interaction between 7, 9 and 11 days irrigation intervals and 15, 20 and 25 cm distances between plant rows. Each plot consisted of 3 plant rows, every one is 10 m long. Each plot area was either 4.5, 6 or 7.5 m2. Seeds were sown for two successive seasons, 2004/2005 and 2005/2006, at a rate of 50 kg/fed. on 16/11. After a 39 days pretreatment period, irrigated every 3 days, irrigation interval treatments started for all plots on 25/12. The 7 days irrigation interval treatment ended on 22/4. Its last irrigation occurred on 16/4. The 9 days irrigation intervals treatment ended on 20/4. Its last irrigation took place on 12/4. The 11 days irrigation interval treatment, ended on 24/4. Its last irrigation occurred on 14/4.
Treatments were studied by determining the following parameters, soil moisture content, soil salinity distribution, evapotranspiration and water use efficiency. In addition, growth characters, yield and its components, as well as, chemical composition of the three studied crops were determined.
A split-plot design, with three replications was used. The irrigation treatments were randomly distributed in main plots, whereas, the distance between lines or rows were allowed to the sub-plots.
Data were tested for the analysis of variance. Duncan’s multiple range test was used, for comparisons among the treatments means.
The results are summarized as follow:
5.1 Soil Moisture Content Distribution
• Soil moisture content of surface layer depth (0-30 cm) decreased with increasing irrigation intervals and distance between irrigation lines or plant rows, before and after irrigation for sugar beet, fodder beet and wheat plants.
• The soil moisture content increased gradually, from the beginning of the establishment growth period until harvest, as a result of increasing irrigation water quantity.
• The highest soil moisture content before and after irrigation, was found at the shortest irrigation intervals (3 and 7 days, for beet plants and wheat plants, respectively) with 40 cm distance between irrigation lines, for beet and 15 cm distance between plant rows for wheat.
• The lowest values of soil moisture content, before and after irrigation, were found at the longest irrigation intervals (7 and 11 days), with the lowest planting density (60 cm distance between irrigation lines and 25 cm distance between plant rows) for beets and wheat plants, respectively.
5.2 Soil Salinities Distribution
• Soil salinity increased with increasing irrigation intervals and distance between irrigation lines, or plant rows, before and after irrigation, for sugar beet, fodder beet and wheat plants.
• Soil salinity increased gradually from the beginning of the establishment growth period until the end of the season.
• The highest value of soil salinity was recorded with I3 x d3 for beets and wheat.
• It is not recommended to use the treatment I3 x d3 for beets and wheat, because it is expected that soil becomes saline in the future.
5.3 Effect of Irrigation Intervals
5.3.1 Actual Evapotranspiration (ETa)
• The actual evapotranspiration (ETa) was decreased, with increasing irrigation intervals for sugar beet, fodder beet and wheat plants in both seasons.
• The highest value of ETa was found for 3 days treatment, followed by 5 and 7 days treatments, respectively, for sugar and fodder beet, but the highest value of ETa was found for 7 days treatment followed by 9 and 11 days treatments, respectively for wheat plants.
5.3.2 Crop Yield
a) Sugar and fodder beet
• Treatment 3 days irrigation interval, had the highest values for fresh and dry of roots and tops yields in both seasons.
• Treatment 7 days irrigation interval, had the lowest ones in both seasons.
• Treatment 5 days irrigation interval had the highest values of sugar yield, while treatment 7 days irrigation interval, had the lowest ones in both seasons.
b) Wheat
• Treatment 7 days irrigation interval had the highest values for fresh and dry of grains and straw yields and weight of 1000 grain in both seasons.
• Treatment 11 days irrigation interval had the lowest ones in both seasons.
5.3.3 Water Use Efficiency (WUE)
a) Sugar and fodder beet
• The highest water use efficiency was found for the treatment 7 days followed by 5 days and 3 days treatments, respectively.
b) Wheat
• The highest water use efficiency was found for the treatment 11 days followed by 7 days and 9 days treatments, respectively.
5.3.4 Plant Growth Parameters
a) Sugar and fodder beet
• Treatment 3 days irrigation interval, had the highest values for root length, top length, root diameter, number of leaves per plant and fresh and dry weight of root and top in both seasons, while treatment 7 days irrigation interval had the lowest values.
b) Wheat
• Treatment 7 days irrigation interval, had the highest values for plant height and number of tillers per m2 in both seasons, while treatment 11 days irrigation interval had the lowest values.
5.3.5 Crop Major Constituents
a) Fodder beet
• Treatment 3 days irrigation interval, had the highest values of root and top content of crude protein, but it gave the lowest value of crude fiber and total ash content in both seasons.
• Treatment 7 days irrigation interval, had the lowest root and top content of crude protein, but it gave the highest crude fiber and total ash content in both seasons.
b) Wheat
• Treatment 9 days irrigation interval had the highest value of grains content of crude protein in both seasons, while treatment 7 days irrigation interval had the lowest one.
5.4. Effect of Plant Density
5.4.1 Actual Evapotranspiration (ETa)
• The actual evapotranspiration (ETa) was decreased with decreasing the distance between irrigation lines, for sugar and fodder beet, but it was decreased with decreasing the distance between plant rows for wheat in both seasons.
• The highest value of ETa was found for 60 cm distance between lines, followed by 50 and 40 cm distance between lines treatments, respectively for sugar and fodder beet, but the highest value of ETa was found for 25 distance between rows followed by 20 and 15 distance between rows, treatments, respectively for wheat plants.
5.4.2 Crop Yield
a) Sugar and fodder beet
• Treatment 60 cm distance between irrigation lines, had the highest values for fresh and dry roots and tops yields in both seasons, while, 40 cm distance between irrigation lines, had the lowest values in both seasons.
b) Wheat
• Treatment 25 cm distance between plant rows had the highest values for fresh and dry grains and straw yields in both seasons. However, treatment 15 cm distance between plant rows had the lowest values in both seasons
5.4.3 Water Use Efficiency (WUE)
• Average water use efficiency values were about 10 kg of fresh sugar roots per one cubic meter of consumed water.
• Average water use efficiency values varied between approximately, 14 to 16 kg of fresh fodder beet roots, per one cubic meter of consumed water.
• Average water use efficiency values slightly varied from 1.81 to 1.91 kg of fresh wheat grains, per one cubic meter of consumed water.
5.4.4 Plant Growth Parameters
a) Sugar and fodder beet
• Treatment 60 cm distance between irrigation lines, had the highest root length, root diameter, number of leaves per plant and fresh and dry roots and tops weight in both seasons, but it gave the lowest top length.
• Treatment 40 cm distance between irrigation lines, had the lowest root length, root diameter, number of leaves per plant and fresh and dry roots and tops weight in both seasons, but it gave the highest top length.
b) Wheat
• Treatment 15 cm distance between plant rows, had the highest plant height and the lowest number of tillers per m2 in both seasons.
• Treatment 25 cm distance between plant rows, had the lowest plant height and the highest number of tillers per m2 in both seasons.
5.5. Effect of Interaction Between Irrigation Intervals and Plant Density
5.5.1 Actual Evapotranspiration (ETa)
a) Sugar beet
• ETa values were more influenced by irrigation intervals than by the distances between irrigation lines.
• Irrigation water increased ETa at any distance between irrigation lines.
• The average values between seasons, for the total consumed water of the 3, 5 and 7 days irrigation intervals during all growth periods were 831.8, 484.28 and 239.00 mm, respectively.
• The average values between both seasons for the total consumed water of the 40, 50 and 60 cm distances between irrigation lines were 478.27, 515.41 and 559.93 mm, respectively.
• The highest average ETa values between seasons, for sugar beet were 879.73 mm for irrigation every 3 days, when irrigation lines of 60 cm apart.
• The least average depth of consumed water was 209.97 mm when sugar beet was irrigated every 7 days, and irrigation lines of 40 cm apart.
b) Fodder beet
• ETa values were more influenced by irrigation intervals, than by the distances between irrigation lines.
• Irrigation water increased ETa at any distance between irrigation lines.
• The highest total average value of ETa between seasons for fodder beet, was 866.76 mm for irrigation every 3 days, when irrigation lines of 60 cm apart.
• The least average depth of consumed water was 185.02 mm, when fodder beet was irrigated every 7 days and irrigation lines of 40 cm apart.
c) Wheat
• ETa values were more influenced by irrigation intervals, than by the distances between plant rows.
• Irrigation water increased ETa at any distance between plant rows.
• The highest total average value of ETa between seasons for wheat, was 486.38 mm for irrigation every 7 days, when the distance between plant rows of 25 cm.
• The least average depth of consumed water was 107.58 mm, when wheat was irrigated every 11 days, and plant rows of 15 cm apart
5.5.2 Crop yield and Water Use Efficiency (W.U.E):
a) Sugar beet
• The largest values for roots fresh or dry weights, were obtained for sugar beet irrigated every 3 days, and the distance between irrigation lines of 60 cm; 28.905 and 4.853 ton/fed, respectively.
• The least amounts of produced roots fresh and dry weights, were obtained for sugar beet irrigated every 7 days, and irrigation lines of 40 cm apart; 16.449 and 2.812 ton/fed, respectively.
• The largest values for sugar yield were obtained, for sugar beet irrigated every 5 days, and the distance between irrigation lines of 60 cm; 5.667 ton/fed, but the lowest values were obtained when irrigated every 7 days and the distance between irrigation lines of 50 cm; 4.085 ton/fed.
• The largest values of water use efficiency, were obtained for sugar beet irrigated every 7 days, and the distance between irrigation lines of 40 cm; 18.65 kg/m3, but the lowest values were obtained when irrigated every 3 days, and the distance between irrigation lines of 40 cm; 7.34 kg/m3.
b) Fodder beet
• The largest total average roots fresh and dry weights were 56.180 and 22.965 ton/fed, respectively, when fodder beet was irrigated every 3 days, and the distance between irrigation lines of 60 cm.
• The least average values for the same parameters were 19.455 and 8.284 ton/fed., respectively, when fodder beet was irrigated every 7 days, and the distance between irrigation lines of 40 cm.
• The largest values for water use efficiency were obtained for fodder beet irrigated every 7 days, and the distance between irrigation lines of 40 cm; 25.07 kg/m3, but the lowest values were obtained when irrigated every 3 days, and the distance between irrigation lines of 40 cm; 12.10 kg/m3.
c) Wheat
• The highest obtained values for fresh grains and straw yields in tons per feddan, were 3.523 and 3.256 ton/fed, respectively, for wheat irrigated every 7 days and plant rows of 25 cm. apart.
• The least obtained values for fresh grains and straw yields in tons per feddan were, 1.891 and 1.935 ton/fed for wheat irrigated every 11 days, and plant rows of 15 cm. apart.
• The largest values of water use efficiency were obtained for wheat irrigated every 11 days, and the distance between irrigation lines of 15 cm; 4.19 kg/m3, but the lowest values were obtained when irrigated every 9 days, and the distance between irrigation lines of 25 cm; 1.49 kg/m3.
5.6 Economic Evaluation
• The highest return pound was obtained with irrigation every 3 days for fodder beet, while the lowest return pound was obtained with irrigation every 9 days for wheat.
• There were inverse relationship between yield and irrigation intervals, while there were positive relationships between yield and the quantity of water consumed and distances between lines or rows, for sugar beet, fodder beet and wheat crops.