Effects of Irrigation Interval and Method on Growth, Photosynthesis, Yield, and Water Use Efficiency of Maize in the Nile Delta of Egypt

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(1)Trop. Agr. Develop. 64 （4）：178 － 188，2020. Effects of Irrigation Inter val and Method on Growth, Photosynthesis, Yield, and Water Use Efficiency of Maize in the Nile Delta of Egypt Aki KUBOTA1, *, Yosri ATTA2, Ahmed ABDEL-FATTAH2, Sayed El-BEHLAK 3, Yoshiya SHINOTO4, Ayaka FUKUNAGA1, and Sachio MARUYAMA5 1. NTC International Co., Ltd., 1-42-20 Kameido, Koto-ku, Tokyo, 136-0071 Japan. 2. Water Management Research Institute, National Water Research Center, P.O. Box 13621/5, Qalubia, Delta Barrage, Egypt. 3. Egyptian Bio-Dynamic Association, 3 Cairo Belbes Desert Road, El Salam City, Cairo, Egypt Tohoku Agricultural Research Center, National Agriculture and Food Research Organization (NARO), 4 Akahira, Shimo-. 4. kuriyagawa, Morioka, Iwate, 020-0198 Japan 5. University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572 Japan. Abstract A study to elucidate the possibility of water-saving irrigation methods for maize (Zea mays L.) by reducing frequency and wetting area was conducted in 2013 and 2014 on Vertisols of the Nile Delta. The water-saving methods tested were prolonging the interval by about 1 week and strip method with wide planting bed which results in reducing number of irrigation ditches by 50%. The water-saving ratio was higher with strip method (26 - 31%) than prolonging the interval (8 - 19%). The growth, photosynthetic rate, and grain yield of maize plants were investigated under 4 treatments, i.e. the combination of interval (about 2 weeks or 3 weeks) and method (furrow or strip). Although the treatments had different effects in 2 years, our results can suggest that prolonging the interval by about 1 week from the conventional interval has a risk of yield reduction in the field with soil clay contents equal to or less than 50%, while, strip method has possibility to sustain the grain yield of maize and to improve water use efficiency, calculated as the grain yield divided by the total amount of irrigation water, as much as 71% when irrigation interval was practiced as conventional. Under the prolonged irrigation interval, maize with strip method showed low photosynthetic rates caused by water deficit. Thus, the strip irrigation method with the conventional interval is recommended for saving limited water resources without yield reduction of maize in the Egyptian Nile Delta. Key words: Photosynthetic rate, Prolonged irrigation interval, Soil water potential, Strip irrigation method, Vertisols, Water-saving ratio. Introduction. years ago. This causes the high demand of food production and decreases water resources which can be used. Water is the fundamental factor for agriculture in. per capita. Although maize is widely cultivated within. Egypt as the country has arid desert climate with annual. the Nile Delta, the production has not been sufficient to. average precipitation of less than 100 mm (El-Nahrawy,. fulfill the demand, and about 51% of the consumption is. 2011). Crop production in Egypt is entirely dependent. imported (data of 2017 from FAO, 2020).. on irrigation by the water from the River Nile, and. Due to the limited water resources, increase of. spend approximately 81% of the water use in the country. water needs, and high demand of maize, proper water. (Noaman, 2017). The present cultivated area is about. management with more efficiency needs to be achieved.. 3.5% of the total area of the country (Zaghloul, 2013). To enhance the effective water saving on-farm manage-. around and within the Nile Delta. The agriculture land. ment, there are two possible approaches, i.e. reducing. is 100% irrigated.. the irrigation frequency and limiting the wetting zone.. In Egypt Maize (Zea mays L.) is one of the most. Former approach can be practiced by prolonging the. important summer crop, and utilized for human con-. irrigation interval from the conventional practice, where. sumption, for animal feed, and as industrial materials for. maize is commonly irrigated every 12-15 days (ARC,. starch and oil production. Annual population growing. 2012) on the heavy clayey Vertisols in the Nile Delta.. rate is high and now 1.8% (Worldometers, 2019), and the. The latter approach can be practiced by drip irrigation. population was increased by almost three times since 50. method or reducing the number of irrigation ditches. Several studies are reported for the aim of water-. Communicated by N. Kurauchi Received Sep. 20, 2019 Accepted Jul. 11, 2020 * Corresponding author akubota2002@yahoo.co.jp. saving crop production. El-Hendawy et al. (2008) tried to develop drip irrigation system for maize production, and found that the system has advantage only on sandy soils with deep percolation. Practicing drip irrigation is costly.

(2) Kubota et al.: Water-saving irrigation for maize in Egypt. 179. for most of local farmers, especially with cereal cultiva-. studies were carried out. For crop production aspects. tion like maize. The drip irrigation is mainly practiced. with different irrigation approach, Sugita et al. (2017),. for fruit production in the sandy soil and for horticulture. and El-Kilani and Sugita (2017) clarified the water. under the facility in Egypt. Abo-El-Kheir and Mekki. requirements, using ET as an indicator, of several crops. (2007) showed that maize grain yield decreased by 28%. under various irrigation methods, and Maruyama et al.. and 36% when irrigation events were omitted during. (2017) studied the performances, such as plant growth. silking and grain filling stages, respectively. Ibrahim and. and yield, of several crops under various irrigation. Hala (2007) also investigated that prolonging irrigation. methods. Kubota et al. (2016) studied about irrigation. intervals from 10 to 18 days reduced the maize grain. intervals for maize production, including effects on its. yield in Egypt. However, Kubota et al. (2016) reported. photosynthetic rate, in different location in the Nile. no yield reduction in spite of the prolonged irrigation. Delta from the present study. In our present study the. interval on the heavy clayey Vertisols with high ground. objective was to analyze the response of maize plants,. level.. such as photosynthetic rate, plant growth, grain yield,. One of the methods to reduce the number of irriga-. and WUE, under two water-saving approaches which. tion ditches per area in order to limit the wetting zone. were prolonging irrigation interval and strip irrigation. is strip irrigation method with growing maize on wide. method with wide planting bed. The primary target was. planting bed (Maruyama et al., 2017). This strip method. to find out the effective water-saving irrigation method. was first proposed by Atta and Ibrahim (2005) for rice. without yield reduction of maize for farmers in Egyptian. cultivation and then for maize cultivation (Atta, 2007).. Nile Delta.. This approach of strip method decreased irrigation water use by 35% for rice and 53% for maize as maximum, and even increased maize grain yield. In the study of Atta. Materials and Methods Experimental site. and Ibrahim (2005) and Atta (2007), plants were grown. The field experiment was conducted from June to. within the furrow, however, maize were planted on the. September in 2013 and 2014 in the experimental field of. planting bed in the present study as same as reported by. Water Management Research Institute (WMRI) located. Maruyama et al. (2017).. in Zankalon Village of Sharqia Governorate (Fig. 1). The. In water-saving approach in crop production, to find. experimental field was located at 30°34’50.04”N and. the threshold is the key for deciding whether we can. 31°25’59.94”E. The soil is classified into Vertisols by Soil. recommend the method to farmers or not. Even if watersaving ratio is high no farmers would accept the method. Taxonomy. It had clay contents between 47 and 48%, and bulk density of about 1.6 g cm-3 until 80 cm deep as in-. when crop productivity decreases. If water-deficit is not. vestigated (Table 1). The climate of the area belongs to. too severe to cause major physiological damage, plants. arid climate characterized by very dry hot summer, and. try to adapt physiologically and morphologically to. the field did not receive any rain during the experiment. minimize water use. Some studies concluded that root. in both years (Table 2). Temperature was consistent. development was improved under reduced irrigation. during the maize growing period in both years, and the. (Nicoullaud et al., 1994; Sharp and Davis, 1985; Kang. medium temperature stayed between 26 and 28° C.. et al., 2000). If the water reduction is exceeded, plants try to adapt by delaying dehydration through reduction. Crop management and irrigation methods. of stomatal conductance, lower the photosynthetic rate. The experimental plots were prepared according. and then crop productivity (Yu et al., 1997; Shinoto et. to the treatments. The experimental treatments had two. al., 2018).. factors using split plot design with three replications.. Water use efficiency (WUE), the ratio of the target. The main factor was irrigation intervals, i.e.. crop production to the amount of irrigated water, is also. conventional and prolonged interval. The conventional. the practical means to evaluate water-saving irrigation. interval plots were irrigated with about 2-week interval. method for sustainable farming. Several studies showed. as recommended for maize cultivation by Agriculture. that WUE was improved under reduced irrigation. Research Center (ARC) (2012), and the prolonged inter-. (Asseng et al., 1998; Mansouri-Far et al., 2010; Kubota. val plots were irrigated at about 3-week interval since. et al., 2016).. after the 3rd irrigation (July 25) in 2013, and after 2nd. This study was a part of a research project con-. irrigation (June 25) in 2014. The irrigation schedule had. ducted in Egyptian Nile Delta, and several different. to be adjusted by a few days in some cases due to the.

(3) 180. Trop. Agr. Develop. 64 （4）2020. Zankalon Village. Fig. 1. Location of Zankalon village. (Source: Egypt Map, PBWORKS, 2015) Table 1. Soil characteristics of the experimental field in Zankalon village. Soil depth (cm). Sand (%). Silt (%). Clay (%). Bulk density (g cm-3). 0-20. 14. 39. 47. 1.57. 20-40. 15. 37. 48. 1.60. 40-60. 15. 37. 48. 1.60. 60-80. 14. 39. 47. 1.55. Table 2. Meteorological data in the experimental field during the maize growth. Monthly average Year. Month Min. Max. 2013. June. 20.4. 35.0. July. 21.0. August. 19.9. September 2014. Temperature (%). Precipitation (mm). Medium. E pan (mm day-1). Relative humidity (%). Wind speed (m s-1). 27.7. 11.0. 41.7. 2.3. 0.0. 33.3. 27.2. 8.3. 49.9. 1.5. 0.0. 35.8. 27.8. 6.7. 47.8. 0.7. 0.0. 18.1. 33.8. 26.0. 5.7. 46.0. 0.8. 0.0. June. 20.0. 33.5. 26.8. 9.8. 48.0. 2.0. 0.0. July. 21.6. 33.6. 27.6. 7.8. 54.6. 1.2. 0.0. August. 20.9. 35.8. 28.4. 6.7. 59.3. 0.8. 0.0. September. 18.4. 34.3. 26.4. 6.1. 55.8. 0.8. 0.0. Source: Meteorological Station, Zankalon Experimental Field, WMRI.. availability of water in the main canal. The sub factor was irrigation methods with conventional furrow with 70 cm between rows, and strip. experimental field design of the institute. A branch waterway was at the middle of the plot which was parallel to the long side (Fig. 3).. irrigation with 140 cm between the centers of wide beds. Maize (Zea mays L., ‘Three Ways Cross 324’) was. (110 cm wide) with 2 rows of planting each (Fig. 2). As. sown in the field on June 16 in 2013 and June 8 in 2014.. a result of strip irrigation method, the number of the. Two seeds were sown in each hill, and thinned to one. irrigation ditches (or furrows) per area was reduced to. plant after seedling emergence. Water was irrigated. a half of the conventional furrow irrigation method. The. according to the practice of regional farmers. The ir-. distance between plants on row was 25 cm, and the plant density was 57140 plants ha-1 in all the plots. In all cases. rigation water was supplied through a weir and the. the height of planting bed was 15 cm. The plot size was. the water front reached the end of the furrow. The time. 17.5 m wide and 20 m long for 1st and 2nd replication. of irrigation was recorded to calculate the quantities of. plots, and 20.5 m wide and 20 m long in 3rd replication. applied water using an equation [Q = c L h1.5], where Q is water discharge (in m3 min-1), c is correction coefficient. plots. The plot size slightly differed due to the original. waterway at the middle of each plot, and stopped when.

(4) 181. Kubota et al.: Water-saving irrigation for maize in Egypt. 70 cm. 140 cm. Fig. 2. Sketch of furrow irrigation method (left) and strip irrigation method (right).. tion (PF) and the combination of both water-saving treatments (PS) could save 8 - 19% and 28 - 37%, respectively. Fertilizer was applied by a method practiced by. Water. 17.5 or 20.5 m. the regional farmers. All plots received 274 kg N, 55 kg P2O5 and 57 kg K2O ha-1 in total. Urea, superphosphate and potassium sulfate were used to apply these nutrient rates. Superphosphate was applied during land prepara-. 20 m. tion, and 1/5 of the urea and all the potassium sulfate. Fig. 3. Schematic diagram of a plot, water way, location of tensiometer installation and plant sampling. “⇛” shows the water way of irrigation. “” indicates the location of tensiometer, “ and ” indicate the location of photosynthesis measurement and plant sampling during the maize growth.. were applied with the 1st irrigation after seeding. The remaining amount of urea was applied at 1 month after sowing and at the beginning of the tasseling stage (2/5 of urea each time). Maize were harvested on Sep 22 (98 days after sowing; DAS) in 2013 and Sep 16 (100 DAS) in 2014.. (0.3), L is the length of the weir (1.5 m) and h is the head in the weir (in m) (El-Khateeb et al., 2009).. Monitoring soil water status. Table 3 shows the treatments, treatment symbols,. Soil water potential in each plot was measured at. irrigation frequency, irrigated water amount and water. 10 cm, 20 cm and 40 cm depth from the soil surface. saving ratio, comparing with the irrigation treatment of. between June and September in the maize growing. conventional interval and conventional furrow method (CF) as a standard treatment. In CF plots 5353 m3 ha-1. seasons in 2013, using tensiometers (DIK-8343, 8333,. and 5514 m ha-1 of water were applied in 2013 and 2014,. tensiometers for measuring at 10, 20, 40 cm depth was. respectively. Under the conventional irrigation interval,. installed at around the center of the half the plot which. the strip irrigation method (CS) saved 26 - 31%. While,. was divided by waterway (Fig. 3), and the mean values. prolonging the interval with conventional furrow irriga-. over the 3 replicated plots are presented. The soil water. 3. 833, Daiki Rika Kogyo Co. Ltd.). In each plot, a set of. Table 3. Irrigation amount and water saving ratio of each irrigation treatment. Year. Irrigation interval Irrigation method. 2013. Conventional Prolonged. 2014. Conventional Prolonged. z. Treatment Total irrigation symbol times. Total irrigation Water saving ratio z amount 3 1 (m ha ) (%). Furrow irrigation. CF. 6. 5353. 0. Strip irrigation (Wide-bed furrow). CS. 6. 3978. 25.7. Furrow irrigation. PF. 5. 4936. 7.8. Strip irrigation (Wide-bed furrow). PS. 5. 3866. 27.8. Furrow irrigation. CF. 6. 5514. 0. Strip irrigation (Wide-bed furrow). CS. 6. 3829. 30.6. Furrow irrigation. PF. 5. 4492. 18.5. Strip irrigation (Wide-bed furrow). PS. 5. 3488. 36.7. : Water saving ratio was calculated using CF treatment as a control..

(5) 182. Trop. Agr. Develop. 64 （4）2020. tension was recorded twice a week.. tosynthetic rates were recorded 8 times with an interval of 10 sec for each leaf by AutoLog, and the mean value. Maize plant growth. was presented. The diurnal changes of photosynthetic. Maize plants were sampled at the beginning of. photon flux density (PPFD) which the leaves received. their reproductive phases to investigate the effects. were also recorded. The vapor pressure deficit in the. of irrigation intervals and irrigation methods on plant. chamber was not controlled, and it was 1.70 ± 0.55 kPa. growth during the season. Those were Aug 24 (69. on Aug 10 and 1.66 ± 0.86 kPa on Aug 11. On the day of. DAS) which was early grain filing stage in 2013, and. measuring the soil samples were taken from 0 - 20 cm. Aug 9 (62 DAS) which was early ear setting stage in. depth , and dried at 105 °C for 48 h in the oven to obtain. 2014. Three plants were sampled from each plot, and. soil moisture content.. the plant height, number of leaves and SPAD values. (2) Response of photosynthetic rate to PPFD was. were recorded. They were moderately-growing plants. measured at between 9:00 and 12:20 using LED chamber. selected at around the center on the diagonal line of half. with artificial light on Aug 12. The PPFD applied were between 0 and 2000 μm-2 s-1. The measurement was car-. part of the plot which was divided by waterway (Fig. 3). The plants were separated to leaf, stem and ear, and dried in oven at 70°C for 72 h to obtain the dry weight. ried out with the following order of PPFD; 2000, 1500, 1200, 1000, 800, 600, 400, 200 100, 50 and then 0 μm-2 s-1,. of each part. Water use efficiency at this stage (WUEER). by AutoLog of the portable photosynthesis system (once. was calculated as the above-ground dry weight divided. at each PPFD).. by the amount of irrigated water from sowing day to the investigated day.. Grain yield and the final WUE. Measurement of photosynthetic rate. from 3 spots in each plot, i.e. 9 plants from each plot,. At harvest time, 3 plants were randomly selected In 2014 photosynthetic rate of maize leaves were. on Sep 22 in 2013 and Sep 16 in 2014. These 3 spots. measured using a portable photosynthesis system (LI-. were selected on the diagonal line of half part of the. 6400 EX, LI-COR Inc.) at the beginning of reproductive. plot which was divided by waterway. After maize plants. growth. This was conducted 1 and 2 days after the. were cut at the soil level, the plants were separated. sampling of maize plants for growth investigation. The. into each part, and the ears were first dried under the. photosynthetic rates were measured as (1) diurnal. sun. The grains were separated from the ears, and then. changes within a day using the natural sun light, and. dried in the oven at 70°C for 72 h together with other. (2) response to different photosynthetic photon flux. parts of plant samples to obtain their dry weight. The. density (PPFD) values, i.e. light response curve of. data of grain yield was obtained by adjusting the weight. photosynthesis. For all the measurements, the 3rd leaf. to 15% moisture content. The WUEGY was calculated as. from the flag leaf was selected in the 3 plants in each. the grain yield divided by the total amount of irrigation. plot which were close to the plants for plant growth. water (from sowing to the harvest). The WUEDW was. investigation. The air flow rate sent to the chamber was 500 μmol s-1. The ambient CO2 concentration sent to the. calculated as the final above-ground dry weight divided. chamber was 372 ± 24.6 μmol mol-1 (Aug 10) and 378 ± 26.6 μmol mol-1 (Aug 11) for recording diurnal changes,. the harvest).. and 371 ± 7.6 μmol mol-1 for light response curve (Aug. analyzed by using Statistix ver. 9 (Analytical Software.. 12). The temperature in the chamber was controlled. Co. Ltd.).. at 30°C. The procedures of these 2 measurements are given below. (1) To investigate the diurnal changes of the pho-. by the total amount of irrigation water (from sowing to The effects of the treatments in all data sets were. Results Change in soil water potential. tosynthetic rate, measurements were carried out every. Figure 3 shows the change of soil water potential. 1.5 h between 7:30 and 18:00. The measurements were. measured from June 23 to Sep 23 in 2013. From the end. conducted on Aug 10 for conventional interval plots (CF. of August soil up to 40 cm depth tended to get drier. and CS), and Aug 11 for prolonged interval plots (PF and. than the earlier time. At the middle of September, the. PS). The plastic filmed chamber containing the maize. soil became drier again especially in the plots of CS and. leaf was held perpendicular to the sunlight to measure. PS, and the moisture states at 10 cm depth reached the. the actual photosynthetic rate under natural light. Pho-. lento-capillary point (-50 kPa). Just after the irrigation.

(6) 183. 30 20. 18 - June. 40. 4 - Jul. 50. 5 - Sep. CF. 7 - Aug. Soil Water Poten�al (- kPa). 60. 25 - Jul. 70. 22 - Aug. Kubota et al.: Water-saving irrigation for maize in Egypt. Lento-Capillary Point. 10 cm 20 cm. Field Capacity. 10 0 15-Jun 22-Jun 29-Jun 6-Jul. 13-Jul 20-Jul 27-Jul 3-Aug 10-Aug 17-Aug 24-Aug 31-Aug 7-Sep 14-Sep 21-Sep 28-Sep. 30 20. 18 - June. 22 - Aug. 40. 4 - Jul. 50. 7 - Aug. Soil Water Poten�al (- kPa). 25 - Jul. CS. 60. 5 - Sep. 70 Lento-Capillary Point. 10 cm 20 cm. Field Capacity. 10 0 15-Jun 22-Jun 29-Jun 6-Jul. 13-Jul 20-Jul 27-Jul 3-Aug 10-Aug 17-Aug 24-Aug 31-Aug 7-Sep 14-Sep 21-Sep 28-Sep. 30. 4 - Jul. 40. 18 - June. 50. 1 - Sep. PF 25 - Jul. Soil Water Poten�al (-kPa). 60. 15 - Aug. 70 Lento-Capillary Point 10 cm 20 cm. 20 Field Capacity. 10. 13-Jul 20-Jul 27-Jul 3-Aug 10-Aug 17-Aug 24-Aug 31-Aug 7-Sep 14-Sep 21-Sep 28-Sep. Soil Water Poten�al (- kPa). 30 20. 4 - Jul. 40. 18 - June. 50. 15 - Aug. PS. 60. 25 - Jul. 70. 1 - Sep. 0 15-Jun 22-Jun 29-Jun 6-Jul. 10 cm 20 cm. Field Capacity. 10 0 15-Jun 22-Jun 29-Jun 6-Jul. Lento-Capillary Point. 13-Jul 20-Jul 27-Jul 3-Aug 10-Aug 17-Aug 24-Aug 31-Aug 7-Sep 14-Sep 21-Sep 28-Sep. Fig. 4. Change in soil water potential (-kPa) during maize growing period in 2013. The arrows indicate irrigation events. (CF: Conventional interval and furrow irrigation, CS: Conventional interval and strip irrigation, PF: Prolonged interval and furrow irrigation, PS: Prolonged interval and strip irrigation). One reading between July 26 and Aug 4 could not be recorded. Lento-capillary point is the soil moisture status when water cannot move easily thorough soil pores and plant growth slows down with water deficit. It is the “dry” end of readily available water.. on July 25, tensiometer readings could not be taken for. irrigation intervals. The plant height, leaf number,. some uncontrollable reason.. SPAD value and above-ground dry weight did not show any single treatment effect. They had some interaction. Plant growth at the beginning of reproductive. effects such as with SPAD in 2013, and with plant height. phase. and stem dry weight in 2014 where strip method showed. Table 4 shows, in both years, there were no significant effect of irrigation treatments except on. tendency to have positive effect under conventional interval but not under the prolonged interval.. WUEER. Effects of irrigation treatments on WUE until this stage (WUEER) were consistent regardless of the. Photosynthetic activities of maize leaves. years, and the strip irrigation method had higher. Diurnal changes. WUEER than conventional furrow irrigation under both. The diurnal changes of photosynthetic rate of.

(7) 184. Trop. Agr. Develop. 64 （4）2020. Table 4. Above-ground dry weight of maize plants at the beginning of reproductive stage (Aug 24 in 2013: 69 DAS, and Aug 9 in 2014: 62 DAS). Above-ground dry wt (t ha-1). Year (growth stage). Irrigation treatment z. Plant height (cm). Leaf No.. SPAD. 2013. CF. 260.3. 14.3. CS. 283.9. PF. 266.3. PS. (69 DAS: early grain-filling stage). Water irrigated (m3 ha-1). WUEERv (kg m-3). Leaf. Stem. Ear. Total. 50.2. 2.2. 4.9. 1.4. 8.5. 4537. 1.87. 12.7. 52.2. 2.3. 5.1. 1.4. 8.8. 3254. 2.54. 13.0. 54.2. 2.1. 4.8. 0.9. 7.8. 4028. 1.93. 274.8. 13.1. 47.1. 2.4. 4.6. 2.0. 8.9. 3217. 2.78. Interval. n.s. y. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. w. n.s.. Method. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. *. Interval × M ethod. n.s.. n.s.. *x. n.s.. n.s.. n.s.. n.s.. n.s.. CF. 200.3. 14.2. 42.6. 2.3. 3.7. 6.0. 3617. 1.66. CS. 226.7. 14.7. 45.0. 2.3. 5.0. 7.3. 2774. 2.63. PF. 236.0. 14.8. 45.3. 2.4. 4.6. 6.9. 3566. 1.94. PS. 223.7. 15.0. 45.3. 2.5. 4.2. 6.7. 2851. 2.34. Interval. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. Method. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. **. **. n.s.. n.s.. n.s.. *. n.s.. **. 2014 (62 DAS: ear-setting stage). Interval × Method. : CF: Conventional interval and furrow irrigation, CS: Conventional interval and strip irrigation, PF: Prolonged interval and furrow irrigation, PS: Prolonged interval and strip irrigation. y :“n.s.” indicates there was no significant difference at p <0.05. x :“*” and“**” indicate that the difference was significant with p < 0.05 and p < 0.01, respectively. w : The plants in 2014 had not formed ears yet. v : WUEER: Water use effeciency at early reproductive growth stage. z. maize leaves at early reproductive phase were measured in 2014, and the soil moisture contents (by weight) of 0 –. of irrigation interval on photosynthetic rate with PPFD equal to and higher than 200 μmol m-2 s-1, except with. 20 cm depth on the day of measurement were recorded. PPFD of 1500 μmol m-2 s-1. The positive tendency of strip. (foot note of Fig. 5). The soil in CF and CS were drier. irrigation method was shown in photosynthesis under. than PF and PS, and there were little difference between. the conventional irrigation interval but not under the prolonged interval. Under the PPFD of 2000 μmol m-2 s-1. PF and PS. This is because CF and CS plots, and PF and PS plots were irrigated 14 days and 5 days before the measurement, respectively.. the highest rate was 47.3 μmol CO2 m-2 s-1 with CS, and the lowest was 29.3 μmol CO2 m-2 s-1 with PS treatment.. Figures 5a and 5b show that PPFD reached about 1500 μmol m-2 s-1 at midday on both days. Although there. Grain yield, dr y matter production and WUE. were no significant differences in photosynthetic rates. Although the growing environment was the same. among the treatments, there were some tendencies.. in 2013 and 2014 (Table 2), the grain yield differs among. Under the conventional irrigation interval (Fig. 5c),. years (Table 5).. there were little differences between strip irrigation. In 2013 with all parameters (above-ground dry. plots (CS) and furrow irrigation plots (CF), while, under. weight, grain yield, grain number, 100-grain weight,. the prolonged irrigation interval (Fig. 5d), maize leaves. and WUEs) except CGR, values were higher with con-. in the strip irrigation plots (PS) tended to decrease the. ventional interval (Table 5). When irrigation intervals. photosynthetic rates after midday but those in the furrow. were prolonged by about 1 week, dry matter production. irrigation plots (PF) did not reduce the rate until in the. and grain yield decreased with less grain number and. late afternoon. These tendencies of PF and PS were not. less 100-grain weight. While, irrigation method had. corresponding to the soil moisture contents of that day.. significant effects except grain yield, grain number and weight. Strip irrigation method had a positive effect on. Light response curve of photosynthesis. dry matter production under conventional interval, but. Interaction effects of irrigation methods were sig-. negative effect under prolonged interval. Strip irrigation. nificant in the response of photosynthetic rate of maize. method improved both WUEDW and WUEGY significantly. leaves to the PPFD of the artificial light at 600, 1000, 1200 and 1500 μmol m-2 s-1 (Fig. 6). There were effects. under conventional irrigation interval. In 2014 there were no significant effects of irrigation.

(8) -2 s-1) m-2 s-1) PPFD (μmol PPFDm(μmol. 2000. a. 1500 2000. 0. CF CS 7:00. 10:00. 7:00. Photosynthe�c Photosynthe�c rate rate -2 s-1) m-2 s-1) (μmol CO (μmol 2 m CO 2. 40 50 30 40 20 30 10 20 0 10 7:00. 1000 500. CF 16:00 CS. 13:00 Time. 10:00. 50. b. 1500 1000. 500 1000 0 500. b. 2000 1500. a. 1000 1500. 185. Kubota et al.: Water-saving irrigation for maize in Egypt 2000. 5000. 19:00. 0. 13:00 Time. 16:00. 19:00. c c. 7:00. 10:00. 13:00 Time. 7:00. 10:00. 13:00 Time. 50. d. 40 50. d. 30 40 20 30. CF CS 10:00. CF 16:00 CS. 13:00 Time. 0. 10 20 100. 19:00. 0. 7:00. 10:00. PF PS PF PS 13:00 Time. PF PS PF PS 16:00. 19:00. 16:00. 19:00. 16:00. 19:00. 7:00 rate of 10:00 13:00under conventional 16:00 19:00 7:00changes 10:00 13:00 16:00 flux density 19:00 and photosynthesis Fig. 5. Diurnal of photosynthetic photon maize leaves interval Time Time (a, c) and prolonged interval (b, d) of irrigation, measured on Aug 10 and 11, 2014, respectively. (CF: Conventional interval and furrow irrigation, CS: Conventional interval and strip irrigation, PF: Prolonged interval and furrow irrigation, PS: Prolonged interval and strip irrigation) The error bars indicate SD values (n = 3). There were no significant differences between CF and CS, and PF and PS at any measured time (Tukey’ test at p<0.05). Soil moisture contents (w/w) of CF, CS, PF, and PS plots at the surface soil (0-20 cm) were 21.3 ± 0.76, 18.8 ± 0.95, 27.4 ± 0.29 and 28.8 ± 0.26 %, respectively.. PPFD. 0. 50 100 200 400. 600. 800. 1000 1200. 1500. 2000. Interval. n.s.. n.s.. n.s.. **. *. *. **. *. *. n.s.. **. Method. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. Int x Meth. n.s.. n.s.. n.s.. n.s.. n.s.. *. n.s.. *. *. *. n.s.. 50 40. 47.3 42.0. 30. 29.3. Photosynthe�c rate (μmol CO2 m-2 s-1). 36.4. 20. CF CS PF PS. 10 0. -10. 0. 500. 1000. 1500. 2000. PPFD (μmol m-2 s-1). Fig. 6. Light response curve of photosynthesis under different PPFD of maize leaves at beginning of reproductive growth stage (Aug 12, 2014), and results of statistical analysis. (CF: Conventional interval and furrow irrigation, CS: Conventional interval and strip irrigation, PF: Prolonged interval and furrow irrigation, PS: Prolonged interval and strip irrigation) (n.s.: no significant difference at p<0.05, * : significant difference at p<0.05, **: significant difference at p<0.01) The error bars indicate SD values (n = 3).. interval (Table 5). Under both irrigation intervals the. both irrigation intervals. The interaction effects of two. strip irrigation method made dry matter production. treatments were not significant in 2014.. lower than the furrow irrigation method. There were no significant effects of the irrigation method on grain yield. The WUEDW and WUEGY were significantly higher with strip method than with furrow method under. Discussion Irrigated water amount and soil water status The amount of water was controlled by frequency.

(9) 186. Trop. Agr. Develop. 64 （4）2020. and the number of the irrigation ditches per area.. rigation. Those irrigation treatments affected soil water. Prolonging the irrigation interval by about 1 week saved. potential mainly the surface soil (0-10 cm) (Fig. 4). After. 8 - 19%, and the strip irrigation with fewer irrigation. the end of August soil was drier than lento-capillary. ditches saved 26 - 31% (Table 3). This clearly shows that. point in strip irrigation method plots, especially in under. the strip method is more effective in saving water than. prolonged interval (PS). This means the soil water was. reducing the frequency of irrigation events. Although. not enough in PS for maize plant, which can cause water-. the number of irrigation ditches was reduced by 50%. deficit condition.. with strip method, the water applied was not reduced by Dr y matter production and grain yield. 50% because the water seepage horizontally to the wide planting bed.. We obtained different results in 2013 and 2014 in. The water amount saved by prolonging the irriga-. final above-ground dry weight and grain productions.. tion interval were similar to the study with the same. The grain yield range of maize also differed. The final. treatment but in the different experimental field (Kubota. dry weight of maize plants were greater in 2014 than. et al., 2016). In referred study the field experiment was. those in 2013 (Table 5) although at the beginning. conducted in the different location of different Gover-. of the reproductive phase there were no difference. norate in the Nile Delta, and showed that the water was. among years when investigation timing is considered. saved by 8 - 11% by prolonging the interval by 1 week. (Table 4). The greater dry matter production in 2014 is. although the soil characteristics were different with the. corresponding to the higher CGR during reproductive. higher clay contents (60 - 70%) than the presently stud-. phase in 2014 than those in 2013 except CS treatment. ied field (47 - 48%, Table 1). These results also follows. (Table 5). The CGR of all treatments in 2014 and that. the measurement of evapotranspiration in maize fields by Sugita et al. (2017) in the Nile Delta region. In their. of CS treatment in 2013 were quite high and ranged between 30 and 40 g m-2 day-1. An example of high CGR. study, comparing with the standard furrow irrigation. values was also reported in the study of Shinoto et al.. method in maize field, strip irrigation method lowered. (2017) with maize grown in an upland field converted. evapotranspiration rate more than prolonged interval ir-. from rice paddy field. The CGR were between 21. Table 5. Above-ground dry weight of maize plants at harvesting time, grain yield and water use efficiency (WUE). (harvested on Sep 22 in 2013, and Sep 16 in 2014) Above-ground Year. Irrigation treatment z. 2013. CF. 12.9. CS. 17.8. PF. 11.4. PS. 2014. Grain. Above-ground CGR during dry wt 2 investigations (t ha-1) (g m-2 day-1). Irrigation. Grain yield (t ha-1). Grain No (m-2). 100-grain wt (g). Water irrigated (m3 ha-1). WUEDW v (kg m-3). WUEGY u (kg m-3). 15.1. 5.5. 2684. 17.7. 5353. 2.40. 1.02. 31.0. 6.9. 2896. 20.8. 3978. 4.47. 1.74. 12.4. 4.2. 2544. 14.0. 4936. 2.30. 0.85. 3866. 2.48. 0.86. y. 9.6. 2.3. 3.3. 2095. 13.2. Interval. ** x. n.s. w. **. *. **. **. *. Method. *. *. n.s.. n.s.. n.s.. **. **. Interval × Method. **. **. *. n.s.. n.s.. **. **. CF. 21.3. 40.3. 9.6. 2985. 32.2. 5514. 3.86. 1.74. CS. 18.8. 30.2. 8.5. 2739. 31.0. 3829. 4.91. 2.21. PF. 20.9. 36.8. 8.8. 2835. 31.0. 4492. 4.65. 1.96. PS. 3488. 18.1. 30.2. 8.1. 2597. 31.3. 5.20. 2.33. Interval. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. Method. *. *. n.s.. n.s.. n.s.. **. **. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. n.s.. Interval × Method. : CF: Conventional interval and furrow irrigation, CS: Conventional interval and strip irrigation, PF: Prolonged interval and furrow irrigation, PS: Prolonged interval and strip irrigation. y CGR: Crop growth rate. x :“*” and“**” indicate that the difference was significant with p < 0.05 and p < 0.01, respectively. w :“n.s.” indicates there was no significant difference at p <0.05. v : WUEDW: Water use efficiency based on dry weight of above-grounf dry weight. u : WUEGY: Water use efficiency based on the grain yield. z.

(10) 187. Kubota et al.: Water-saving irrigation for maize in Egypt. and 40 g m-2 day-1, in referred study. The dry matter. 2016). The available water of volumetric water content,. production and grain yield of PS in 2013 were very low,. which is generally defined as the difference between soil. which was possibly caused by water deficit indicated. moisture content at field capacity and wilting point, was determined as 0.15 cm3 cm-3 with the surface soil from. by the tensiometer readings (Fig. 4). We cannot clearly explain the reason of these differences among 2 years since climate condition and irrigated water amount were. the present study field (Kubota et al., 2017), while, it was 0.20 cm3 cm-3 with the surface soil of the field from. almost identical (Table 2, Table 5). Only the difference. the referred study (Kubota et al., 2016). The level of. was the sowing date.. ground water also differed among 2 studies. The level. Although the soil moisture data in PS was not lower. was lower in the field of present study (1.34 ± 0.26 m in. than that in PF plot, the photosynthetic rate of maize. 2013 and 1.60 ± 0.20 m in 2014), than that in the field for. leaves in PS plots declined when PPFD raised in midday. the referred study (0.65 - 0.71 m) (calculated from data. and showed that they were under water deficit stress. provided by M. Sugita). These comparison confirmed. (Fig. 4).. that when we try to save water by prolonging irrigation. The photosynthetic rates were measured only once. interval, we need to collect information of soil clay con-. during the maize growth in 2014. The light response. tents, water holding capacity and ground water levels of. curves of photosynthesis showed the tendency of. the target field.. CS>CF>PF>PS. These results, though limited, suggest that the differences in dry matter production among treatment (Table 5) relate to the water deficit condition during their growth.. Water Use Efficiency (WUE) At the beginning of reproductive phase of maize plants, strip method increased WUEER in both years. Effects of irrigation treatments were not consistent. (Table 4). On the investigation at harvest, strip method. with investigated parameters and years. However, one. had positive effects on WUEDW and WUEGY in both years.. can conclude that strip irrigation method has no negative. However, in 2013, strip irrigation could improve WUEs. effect on maize grain yield, while, prolonging the interval. only under the conventional interval. With PS treatment,. may have a risk to reduce the maize yield (Table 5).. dry matter production and grain yield were very low. About strip irrigation method, the result of 2013. and could not contribute to improve both WUEs. In. showed a tendency agreed with the study of Atta (2007),. 2013, under the conventional interval, the effect of. conducted in the same experimental field, that the wide-. strip method was clear. It improved WUEGY by 71%, and. planting-bed strip irrigation increases maize grain yield by 8.5% (6.3 to 6.8 t ha-1) under the conventional irrigation. could be estimated that CS treatment saved about 192. interval, although the difference was not statistically. CF treatment. In 2014, strip method improved WUEs. significant in our study. One of the possibilities why. under both irrigation intervals. Maruyama et al. (2017). the strip method can increase the maize productivity. also reported that the strip irrigation method for maize. is improved aeration in the soil. Kubota et al. (2016). cultivation in Egypt improved WUE, grain yield/ET,. observed unexpected stagnation in photosynthetic rate. by 18% compared with furrow irrigation method. The. for about 6 days after irrigation event with maize plants. ET measured during the maize growing season under. grown in the field within the Nile Delta, and suggested. furrow and strip irrigation method were 356 and 258. this is possibly caused by waterlogging in the clayey. mm, respectively.. L of water to produce 1 kg of maize grain compared to. soil. These results suggest that strip irrigation method. Prolonging interval did not improve WUEDW and. can be an effective method particularly in the clayey soil.. WUEGY in 2013 but decreased. There was no effects of. Our results indicate prolonging the interval by. interval treatments on WUEs in 2014. This again agrees. about 1 week has a risk of reducing the dry matter. with the study of Maruyama et al. (2017) that prolonged. production and grain yield of maize. This result is con-. irrigation interval from 14 to 21 days reduced ET by 3%,. troversy to the study of Kubota et al. (2016) which was. and lowered maize grain yield by 16%, which led to no. conducted in the different location within the Nile Delta.. improvement in WUE.. According to the referred study, prolonging the interval by about 1 week did not affect the maize grain yield. The. Conclusion. soil clay contents of the present study were between 47. The strip irrigation method with wide planting. and 48% (Table 1), while, those of referred study were. bed was more effective in saving water (26 - 31%) than. between 60 and 70% at 0 - 80 cm depth (Kubota et al.. prolonging the irrigation interval by about 1 week (8 -.

(11) 188. Trop. Agr. Develop. 64 （4）2020. 19%). Although the treatments had different effects in 2 years, our results suggest that prolonging the interval by about 1 week from the conventional interval has a risk of yield reduction in the field with soil clay contents equal to or less than 50% and rather low ground water level of 1.3 – 1.6 m. While, the strip irrigation method has possibility to sustain the grain yield of maize and to improve WUEGY as much as 71% when irrigation interval is practiced as conventional. Under the prolonged irrigation interval, maize plants with the strip method showed low photosynthetic rates due to water deficit. Thus, the strip irrigation method with the conventional interval, which is not technically and financially difficult to be practiced by farmers in the region, is recommended for both maize production and saving limited water resources in the Nile Delta. Acknowledgments This study was a part of the JST/JICA project “Sustainable Systems for Food and Bio-energy Production with Water-saving Irrigation in the Egyptian Nile Basin”, SATREPS. We express our appreciation to Prof. Masayoshi Satoh, the project leader, for the initiation, management and encouragement to the study. We also would like to thank the field assistants of WMRI for managing the field in the extremely hot summer, Prof. Michiaki Sugita for providing us with data sets of ground water level of the fields, and Mr. Kentaro Fukunaga for assisting the measurement of photosynthetic rate of maize leaves. References Abo-El-Kheir, M. S. A., and B. B. Mekki 2007. Response of maize single cross-10 to water deficits during silking and grain filling stages. World J. Agr. Sci. 3: 269-272. Agricultural Research Center (ARC) 2012. Maize. Publishing No. 1255, ARC, Ministry of Agriculture and Land Reclamation, Egypt. (in Arabic) Asseng, S., J. T. Ritchie, A. J. M. Smucker, and M. J. Robertson 1998. Root growth and water uptake during water deficit and recovering in wheat. Plant Soil 201: 265-273. Atta, Y. I. 2007. Improving growth, yield and water productivity of some maize cultivars by new planting method. Egypt. J. Appl. Sci. 22: 1-16. Atta, Y. I. and A. A. Ibrahim 2005. Strip transplanting of rice: A new method for increasing water use efficiency under levels of nitrogen fertilization. Egypt. J. Appl. Sci. 20: 133-143. El-Hendawy, S. E., E. M. Hokam, and U. Schmidhalter 2008. Drip irrigation frequency: The effects and their interaction with nitrogen fertilization on sandy soil water distribution, maize yield and water use efficiency under Egyptian conditions. J. Agron. Crop. Sci. 194: 180-192. El-Khateeb, H., M. Khodeir, and M. Meleha 2009. Utilization of seed drill machine for planting flax crop and irrigation water management. Misr. J. Agr. Engineer 26: 1120-1137. El-Kilani, R. M. M. and M. Sugita 2017. Chapter 6. Irrigation. methods and water requirements in the Nile Delta. In: Irrigated Agriculture in Egypt (Satoh, M., and S. Aboulroos. eds.) Springer (Cham, Switzerland) pp. 125-151. El-Nahrawy, M. A. 2011. Country pasture/forage resource profiles: Egypt. FAO (Rome) p. 44. FAO 2020. Crops. In FAOSTST. [Online] http://www.fao.org/ faostat/en/#data/FBS (browsed on June 25, 2020) Ibrahim, S. A. and K. Hala 2007. Growth, yield and chemical constituents of corn (Zea mays L.) as affected by nitrogen and phosphorus fertilization under different irrigation intervals. J. Appl. Sci. Res. 3: 1112-1120. Kang, S., W. Shi, and J. Zhang 2000. An improved water-use efficiency for maize grown under regulated deficit irrigation. Field Crops Res. 67: 207-214. Kubota, A., B., Zayd, H. Fujimaki, T. Higashi, S. Yoshida, M. M. A. Mahmoud, Y. Kitamura, and W. H. A. El-Hassan 2017. Chapter 7. Water ad salt movement in soils of the Nile Delta. In: Irrigated Agriculture in Egypt (Satoh, M., and S. Aboulroos. eds.) Springer (Cham, Switzerland) pp. 153-186. Kubota, A., Y. Shinoto, W. H. A. El-Hassan, and S. Maruyama 2016. Growth, yield and related physiological traits of maize under a prolonged irrigation interval in the Nile Delta of Egypt. Trop. Agr. Develop. 60: 216-225. Mansouri-Far, C., S. A. M. M. Sanavy, and S. F. Saberali 2010. Maize yield response to deficit irrigation during low-sensitive growth stages and nitrogen rate under semi-arid climate conditions. Agr. Water Manage. 97: 12-22. Maruyama, S., S. M. M. Shabl, K. I. Abdel-Gawad, A. Kubota, K. Shimizu, N. Ishikawa, and A. E. D. H. Mohamed 2017. Chapter 9. Agricultural production-cultivation techniques and farming. In: Irrigated Agriculture in Egypt (Satoh, M., and S. Aboulroos. eds.) Springer (Cham, Switzerland) pp. 225-254. Nicoullaud, B., D. King, and F. Tardieu 1994. Vertical distribution of maize roots in relation to permanent soil characteristics. Plant Soil 159: 245-254. Noaman, M. N. 2017. Chapter 1. Country profile. In: Irrigated Agriculture in Egypt (Satoh, M., and S. Aboulroos. eds.) Springer (Cham, Switzerland) pp. 1-8. PBWORKS 2015. Egypt Map [Online] http://4thpuntachica. pbworks.com/f/1315527077/egypt_map.gif (browsed on Nov. 5, 2015) Sharp, R. E. and W. J. Davies 1985. Root growth and water uptake by maize plants in drying soil. J. Exp. Botany 36: 1441-1456. Shinoto, Y., E. Sarobol, and S. Maruyama 2018. Effects of irrigation interval and manure application on growth and yield of fieldgrown maize in Thailand. Trop. Agr. Develop. 62: 177-185. Shinoto, Y., T. Matsunami, R. Otani, H. Kanmuri, and S. Maruyama 2017. Effects of plowing on growth and grain yield of Maize (Zea mays L.) in upland field converted from paddy field in Andosol. Jpn. J. Crop Sci. 86: 151-159. (in Japanese with English summary) Sugita, M., A. Matsuno, R. M. M. El-Kilani, A. Abdel-Fattah, and M. A. Mahmoud 2017. Crop evapotranspiration in the Nile Delta under different irrigation methods. Hydrol. Sci. J. 62: 1618-1635. 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