The impacts of climatic changes on the yield and water use efficiency of maize grown under different sowing dates and two irrigation schemes in arid climate

doi:10.21203/rs.3.rs-2699960/v1

Upper Egypt is characterized by high temperatures in summer and low temperatures in winter, which has a significant impact on the dates of planting maize in this region. The productivity of the maize crop as well as the efficiency of the use of water can be severely affected by planting dates and drought. Consequently, the optimum irrigation level and planting date must be determined based on local conditions.

Two irrigation schemes were used: (1) control (full irrigation water applied), (2) 70% of irrigation water. Field experiments were conducted at the water studies and research complex station, National Water Research Center in Toshka to evaluate two irrigation levels (full irrigation water applied and 70% of irrigation water requirements) under five planting dates (early seeding (mid-February and March), normal (mid- June) and late planting (mid- August and September) in 2019 and 2020) to determine the optimum planting date and irrigation level.

Early SD has increased the days between seeding and plant emergence. Late SD reduced the number of days until the plant matured and had higher grain yields and water use efficiency (WUE). The planting date in September under the irrigation level of 70% achieved the best productivity and the best water use efficiency, where the productivity was 7.01 Mg ha⁻¹ and the water use efficiency was 0.72 kg/m³

The data confirm the general perception of farmers that the September sowing date under 70% irrigation levels is the best within the experimentation area.

Earth and environmental sciences/Climate sciences/Climate change

Earth and environmental sciences/Environmental sciences/Environmental impact

Maize

water use efficiency

irrigation water levels

Water is a key factor in agricultural production and its greatest value, and among human activities agriculture considering the largest user of water [1]. Climate change is a challenging phenomenon that impacts diverse sectors of society, including agriculture, water resources, and water demand for irrigation [2,3]. Agriculture, the main source of sustainable food, is heavily impacted by climate change and extreme weather phenomena such as temperature changes, irregular rains, and water stress [4,5]. These changes affect productivity, water resources and the nutritional quality of agriculture and cause food production to fluctuate, which, heralding a dark future for constant and sustainable cereal-based food production [6,7]. Therefore, adaptation strategies for agricultural systems are needed to deal with the effects of climate change on water demand for irrigation [8].

Water stress is an unavoidable factor that exists in different environments, without recognizing borders and without clear warning, which impedes the yield, quality, and energy of crop biomass [9]. Water stress has adverse impacts on plants such as delayed growth, decline the photosynthesis, and reflecting inhibitions of the main biochemical processes [10]. As water stress continues, plants are adopting some strategies to protect against these stress conditions including a series of indications ranging from essential to auxiliary reactions [11]. These reactions allow plants to adapt to temporary strategies to deal with water stress in the short term, nonetheless, the impacts of antioxidants and enzyme activities cannot be affected by severe or prolonged water stress [12]. Furthermore, the influences of water stress on agriculture are compounded by the unavailability of water resources and rising food demand due to alarming global population growth [13]. In this concern, Soares et al. [2] indicated that global population growth means that production must grow in a sustainable manner.

[14] who found that seeding dates had an important impact on crop phenology (tasseling and silking). Planting season is a very important technological link to maximizing corn yield [15] and thus research is concentrated on the response to corn yield at the planting date [16] . The growing environment may also impact the quality and final composition of corn kernels [17]. Rahman et al. [18] observed a significant effect of planting date on maize yield and yield components. the delayed seeding in Kharif and the summer season reduced the days to tasseling, silking and the length of harvest and also the grain yield [19]. when environmental conditions are not optimal, the number of seeds can be limited by asynchronous (pollen is not released when silks are exposed or receptive) [20] loss of receptivity of silk (silk does not work anymore to support the growth of the pollen tube [21].

Due to the scarcity of water that Egypt suffers from and the importance of maize as an oil crop and as a fodder crop, this study was conducted to determine the most appropriate water need as well as the most appropriate date for planting in the Toshka area.

2.1. Experimental Site.

In the south of Egypt, an open field experiment was conducted at the experimental farm of water studies and research complex station, Egypt, through the two successive seasons of 2019 and 2020, to study the effect of defining the optimum and planting date and irrigation level under extremely arid conditions. The texture of the experimental soil is sandy soil, while the remaining physical and chemical properties are given in Table 1. In the experimental site, the source of irrigation water is groundwater through a well, according to the analysis quality of the water, it has been classified as C₂S₁.

2.2 Meteorological data

The studied area lies in the hyper-arid with a mild winter and a hot summer (the mean temperature of the hottest month is 20-30 °C) [22]. Table 2a and Table 2b presented the averages of meteorological data, which have been collected from the Toshka weather station during the growing seasons.

2.3 Experimental design and agronomic practices

In order to accomplish the purpose of the current study under drip irrigation system, a split-plot design with five replicates was chosen, whereas the sowing dates (early seeding (mid-February- date₁ and March- date₂), normal (mid-June- date₃) and late planting (mid- August – date₄and September- date₅) in 2019 and 2020) were allocated in the main plot, and two of the irrigation water levels, i.e., 100 and 70% of the water requirements. From the field crops institute, agricultural research center, Egypt, a triple hybrid Giza 352 of maize seeds were obtained. This cultivar is recommended as a high production commercial cultivar. Moreover, this cultivar and the implemented methods in the current research complied with international, national, and institutional guidelines and legislation. The fertilization management and the field practices were implemented as recommended by the Ministry of Agriculture in Egypt for the newly reclaimed soils. The cultivar of maize was resistant hybrid to late wilt and the harvesting takes place 110-120 days after sowing. At a rate of 35 kg ha⁻¹, two maize seeds were sown in hills on one side of the dripper’s jet with a spacing between the maize plants of about 20 cm, while the spacing between rows was 50 cm, with a depth of 5 cm. After 2 weeks of emergence, the plants were thinned to maintain one plant per hill and a population density at 10 plants m^-2(100000 plants ha^-1).

2.5. Calculations Related to Irrigation

Crop evapotranspiration (ET_c)

by using Fao Penman-Monteith (Allen et al. 1998) [23], the reference evapotranspiration of maize (ET_o) was calculated using the weather data obtained from Toshka agrometeorological station. The ET_c was calculated according to the following equation:

ET_c = (ET_o × kc stage) (1)

Where

ET_c = the crop evapotranspiration (mm).

ET_o = the reference evapotranspiration (mm).

k_c = the crop coefficient.

The calculation of the irrigation water requirements (100 % Ir) was according to the equation of James (1988)[24] as follows

Where

Ir = the irrigation water requirements (mm).

Et_c = the crop evapotranspiration (mm).

Lf = the leaching factor 10 % (since soil electrical conductivity is low, Lf was neglected).

Dd = time intervals.

Es = irrigation system efficiency.

Furthermore, the applied water irrigation amounts of (70 % Ir) treatment were proportionally obtained from the (100 % Ir) treatment. The ET_c and Ir calculated amounts that are applied to maize crops in the different growth stages during the growing seasons of 2019 and 2020 are demonstrated in Table 3

Water use efficiency (WUE)

The water use efficiency (WUE) was calculated using the following formula:

Where

WUE = water use efficiency (kg m^-3)

Y = yield (kg ha^-1) and

ET_c = equals seasonal actual evapotranspiration (mm).

2.6 Measurements

The following measurements were recorded at the harvest: Average plant height (cm) - Average ear length (cm) - Average number of ears plant^-1 - Average weight of ear (g) - Average number of row ear^-1 - Average 1000 grain index weight (g) adjusted to 15.5% moisture content - grain yield was determined for each plot then converted to Kg ha^-1.

2.7 Statistical analysis

Analysis of variance (ANOVA) was established to determine any statistically significant differences using a package Costat version 6.303. The means were separated through a revised least significant difference (LSD) test at the 0.05 level.

3.1Weather conditions during the 2019 and 2020 growing seasons

The daily weather conditions during the 2019-2020 experience period are shown in Fig. 1. Maximum, minimum and mean temperatures increased starting in January 1, 2019 maximum values in June and minimum values at the end of December 2019 at the start of January 2020. A similar trend was seen in 2020. The average monthly air temperature ranged from 16.58°C (January 2019-2020) to 35.2°C and 33.14°C (July 2019-2020). The lowest relative humidity was recorded in May 2019, where it recorded 15.3%, while its lowest value was recorded in 2020 in the same month, the heights relative humidity was recorded in September 2019, where it recorded 40.6%, while its heights value was recorded in 2020 in the same month which was 43.4%. The highest and lowest wind speeds in 2019 were recorded in September and November and were 3.70 and 2.70 meters/second, respectively, While the lowest and highest wind speeds were recorded in 2020 in February and August, they were 2.75 and 3.48 meters / second, respectively. The average temperature decreased during February, then this average increased during March to reach the highest degree during June, then it began to decrease in August and September 2019. The same occurred in 2020, but the highest average temperatures were registered in August. The average air temperature from February 2019 to February 2020 was 15.95°C and 17.27.6°C, respectively. when average air temperatures in September 2019 and 2020 were 30.65 and 31.65°C, respectively. Air temperature for May 2020 was 47.2% higher than May 2019. The average temperatures at the date₁ and date₅were low during the Pollination and fertilization stages, and this is in contrast to the rest of the planting dates when temperatures increased during the same period. The date₅ was also characterized by higher soil temperatures than the rest of the planting dates. Maize emergence varied according to planting date and the effect of soil and air temperature on seed metabolism. Maize is planted in the middle of the month for all planting dates emerged on February 25, March 21, June 19, August 21 and September 21, respectively. The maize plants have reached the tassel stage on April 18, May 5, August 8, October 2 and November 2, respectively.

3.2Effect of water levels and planting date on the Nitrogen (N), Phosphorus (P) and Potassium (K).

In Fig 1 a. the N contents in corn grain under different sowing dates were SD₂ > SD₃ > SD₅> SD₄> SD₁ The result showed that when the sowing dates were delayed, the concentrations of N in corn grain were increased. In other hand the contents of N, did not change significantly with drought stress.

On the other hand, by comparing the sowing dates under different irrigation levels, higher N contents were obtained with implementing date₂ under Ir₁₀₀ & Ir₇₀irrigation levels, although that significantly equaled the implementing of date₃under Ir₁₀₀ & Ir₇₀or adoption date₅ x adopting Ir₇₀ irrigation level. Likewise, the lowest N contents were obtained by implementing date₁ under Ir₁₀₀ & Ir₇₀irrigation levels.

In Fig 1 b. by comparing the sowing dates under different irrigation levels, higher P contents were obtained with implementing date₁and date₃under Ir₁₀₀ irrigation levels, although that significantly equaled the implementing of date₁and date₃under Ir₁₀₀ or adoption date₂ and date₅ under Ir₁₀₀ & Ir₇₀ irrigation levels. Likewise, the lowest P contents were obtained by implementing date₄ under Ir₁₀₀ & Ir₇₀irrigation levels.

On the other hand, by comparing the sowing dates under different irrigation levels, higher K contents were obtained with implementing date₃ under Ir₁₀₀ & Ir₇₀irrigation levels. Likewise, the lowest K contents were obtained by implementing date₁ under Ir₁₀₀ & Ir₇₀irrigation levels (Fig 1 c).

3.3 Effect of water levels and planting date on the growth parameters of maize.

In Fig. 2 a. by comparing the sowing dates under different irrigation levels, a higher plant high was obtained with implementing date₁ under Ir₁₀₀ & Ir₇₀irrigation levels, date₂ and date₄ under Ir₁₀₀ irrigation levels, respectively, and date₅ under Ir₇₀,although that significantly equaled the implementing of date_2,date₄ under Ir₇₀and date₅under Ir₁₀₀. Likewise, the lowest plant high was obtained by implementing date₃ under Ir₁₀₀ & Ir₇₀irrigation levels.

by comparing the sowing dates under different irrigation levels, a higher ear length was obtained with implementing date₂and date₅under Ir₁₀₀ & Ir₇₀irrigation levels, although that significantly equaled the implementation of date₁anddate₄ under Ir₁₀₀ & Ir₇₀. Likewise, the lowest ear length was obtained by implementing date₃ under the Ir₇₀irrigation level (Fig.2 b)

by comparing the sowing dates under different irrigation levels, a higher grain number was obtained with implementing date₁under the Ir₁₀₀ irrigation level. Likewise, the lowest grains number were obtained by implementing date₃ under the Ir₇₀irrigation level (Fig. 2 c)

by comparing the sowing dates under different irrigation levels, a higher number of row per ear was obtained with implementing date₂under Ir₁₀₀ & Ir₇₀irrigation levels, although that significantly equaled the implementation of date₂anddate₄ under Ir₁₀₀ & Ir₇₀. Likewise, the lowest row ear number length was obtained by implementing date₃ under the Ir₇₀irrigation level (Fig. 2 d).

by comparing the sowing dates under different irrigation levels, a higher grain index was obtained with implementing date₄under the Ir₁₀₀ irrigation level. Likewise, the lowest grain index was obtained by implementing date₁under Ir₁₀₀ & Ir₇₀irrigation levels (Fig. 2 e)

In Fig 2 f. by comparing the sowing dates under different irrigation levels, a higher ear weight was obtained with implementing date₂under Ir₁₀₀ & Ir₇₀ irrigation levels. Likewise, the lowest ear weight was obtained by implementing date₁ and date₃ under Ir₇₀irrigation levels.

3.4 Effect of water levels and planting date on grain yield and water use efficiency.

In Fig 3 a. by comparing the sowing dates under different irrigation levels, a higher grain yield was obtained with implementing date₅under Ir₁₀₀ & Ir₇₀ irrigation levels, although that significantly equaled the implementation of date₁and date₃under Ir₁₀₀ & Ir₇₀ irrigation levels. Likewise, the lowest grain yield was obtained by implementing date₃ under Ir₇₀irrigation levels.

In Fig 3 b. by comparing the sowing dates under different irrigation levels, a higher WUE was obtained with implementing date₅under Ir₁₀₀ & Ir₇₀ irrigation levels. Likewise, the lowest WUE was obtained by implementing date₃ under Ir₁₀₀ & Ir₇₀irrigation levels.

Sowing date is one of the major factors limiting corn crop yield and is also a key factor in determining yield. Therefore, the determination of the optimal sowing date is considered critical to agricultural production, given that the increase in temperature affects crop yield because of the shorter duration of the growing seasons [25].

The obtained findings of the current study indicated that the implementation of sowing maize seeds in the date2 and date3 with the adoption of Ir100 & Ir70 resulted in the highest increase in the accumulated N contents. Moreover, the implementation of sowing corn seeds in the date5 under Ir70 significantly equaled the previous treatment in attaining the highest accumulated N contents. While the lowest accumulated N value was obtained by sowing maize seeds in the date1 under Ir100 & Ir70. In this concern, we hypothesized that contributed to the severe stress (temperature) that maize plants faced, particularly at the filling stage. For clarification, under planting date (date2 and date3), the plants reach to filling stage in the common hottest months (June and August). Therefore, the plant exposed to high stressed temperatures, worked in tend plant toward increase the absorption and accumulation of N, to accelerate the production of the high molecular components, which worked also as a protection process against stress at par with this allowed plants to complete their circle life quickly, these results are matching with [26,27,28]. In the same concern, [29] indicated that under moderate temperatures, the protein (N) percentage was lowest than the grains that were produced under higher temperatures, which matches our findings. However, this tends to seem it has a critical limitation, after crossing it negative impacts will be aroused. In this regard, [30] demonstrated that the absorption and translocation of N in wheat grains were decreased under higher temperatures due to the declinations in nitrate reductase activity in plants. Under these conditions the plants try to increase the uptake of certain nutrient such P, K, sulfur, and sodium which works in maintaining and protecting the cell membranes, enhancing the antioxidant defense system and osmotic potential, which led ultimately in improving the photosynthetic rate [31]. Although the reduction of root growth under higher temperatures condition generally influences adversely on the uptake, assimilation, and translocation processes for the most nutrients [32]. Therefore, by planting the maize seeds in date1, the plants reach to filling stage approximately in April and the beginning of May, thus these conditions allow maize plants to increase their vegetative growth than productivity growth. Which causes a sort of delay in accelerating the uptake and translocation processes of N. After the finishing of the vegetative growth, plants facing unfavorable temperatures degrees, seem it affected the root efficiency, which led to attaining the lowest accumulation of N in maize grains.

Apart from the accumulated N contents, the accumulations of P in the maize seeds seem it were in correlation with the sowing date more than the irrigation water regimes that were adopted. Whereas, we observed that the accumulations of P attained the highest values with the implementation of Ir70 and the cultivation of maize seeds in date1 and date3. Likewise, the lowest values of the accumulated P were obtained in date4, although they were significantly equalized with the cultivation of maize seeds in (date1 under Ir100, date2 under Ir70, and date5 under Ir100). In this regard, we hypothesized that under the sowing dates date1 and date3, maize plants at the beginning of the development growth faced moderate temperature conditions, under these circumstances it works to presence a sort of soil moisture. However, with the reductions in the available water applications (Ir70), led to increasing the soil pH values and were reflected ultimately in the availability of P. It seems that the soil evaporation in date1 and date3 was the lowest, which results in increasing the uptake of P from the rhizosphere in moderate temperature conditions than date4 (low temperature), this finding is in agreement with [33]. Furthermore, by the presence of water stress regimes (Ir70,) under these conditions, we assumed that under these circumstances plant vegetative aerial parts are least active regarding the reductions in the several physiological processes such as transpiration, thus meanwhile the root system becomes the controller of the activities and the priority in these conditions is more uptake and storage of nutrients.

On the other hand, the obtained results showed that the accumulations of K in the maize seeds achieved the highest values by the adoption of date3 with the implementation of Ir100 & Ir70, while, the lowest accumulated K value was obtained by sowing maize seeds in the date1 and date2. In this concern, we assumed that it seems from the date3 a severe temperature and evaporation conditions affect plant growth. Therefore, as a protective strategy, the plant work in increasing the uptake and accumulation of K to deal with these conditions. Since K has a lot of features to improve the plant water status under (water- temperature) stress conditions. This is reflected in the recorded increases of the K accumulations in date3 under the implementation of Ir100 & Ir70. This observation was reported by previous literature [34,35,36] although the relationship between the uptake K and temperature has a threshold point. For example, [37] mention that the threshold point was at 25 oc, and with the continuous raises in the temperature, the uptake of K decreased. Furthermore, [38] reported that plants have the ability to modify nutrient absorption and accumulation according to the temperature that the aerial part or roots are exposed.

From the previous parts, the current study indicates the necessity of determining the purpose that maize seeds will be used for, whereas if the purpose is malnutrition treatment, the cultivation in date3 under Ir70 leads to raising the quality of the seeds and achieving the highest values of N, P, and k. While, if the purpose is the achievement of the highest yield, the results demonstrated that the adoption of cultivated maize seeds in date5 under Ir70, attains the highest maize yield and WUE as well as this implementation is beneficial to mitigate water stress impact and save great amounts of irrigation water applied in the arid climatic conditions. In this respect, we assumed that regard to the enhancements in the yield characteristics, were in agreement with those obtained by [39,40,41]. Moreover, we assumed that by exposing maize plants to water stress in date5 there were some interrelated factors that could partly mitigate the effects of these conditions among them the short duration that maize plants have been exposed to water stress. Therefore, by sowing maize seeds in date5 under Ir70, although the reductions of the applied irrigation water, didn't cause severe adverse impacts, in this regard, [42] indicated that plants when they were exposed to the water reduction, they have the capability of modulating their vegetative and reproductive phenology depending on the most favorable period. Moreover, planting maize seeds in date5 under Ir70 works in the presence of a sort of motivation of plants to enhance the production process, due to the decreases in the growth period which reaches to 100-110 days approximately. Furthermore, the presence of the waves of stress (temperature- drought) conditions led to accelerating the absorption and accumulation of N, which reflected in an increase the photosynthesis, the production of the protein, and plant growth.

Based on this study, the results showed clear impacts of the current climatic changes on the maize and on the transfer of the optimum irrigation level and planting date in the arid conditions, which resulted in improving the maize growth, nutrient uptake, and yield. However, these improvements depended on the water stress pattern adopted. Whereas, the adoption of cultivation maize crops at the normal sowing date in June under the implementation of a limited irrigation regime, leads to attaining the highest quality of the seeds for N, P, and k. Contrariwise, the adoption of the early seeding date in the mid of February under the implementation of the full irrigation regime. Therefore, the current results highlight the importance of exposure maize to a sort of water stress, although further studies are necessary to observe this impact on other regions. According to the current climatic changes, we recommend being transferred the current normal sowing date of maize to become in September under 70% of irrigation water requirements by which maize yield, the uptake of macronutrients, and irrigation water use efficiency can be increased as well as these applications are beneficial to mitigate water stress impact and save great amounts of irrigation water applied in the arid areas.

Acknowledgments The authors would like to thank the Water Studies and Research Complex (WSRC) Station and National Water Research Center (NWRC) for their financial support to conduct this work.

Authors contributions

All authors contributed to the study conception and design. Material preparation, data collection was performed by [Ahmed Dahab]; Ayman M.S. Elshamly contributed to the section Statistical analysis. The first draft of the manuscript was written by [Ahmed Dahab] and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Compliance with Ethical Standards

Conflict of interest. On behalf of the authors, the authors declare that they have no conflict of interest.

Ethics approval and consent to participate

This manuscript is an original paper and has not been published in other journals. The authors agreed to keep the copyright rule.

Data availability The presented datasets during the current study available from the corresponding author on reasonable request.

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Table 1 the physicochemical properties of soil at the experimental site, Egypt during the growing seasons of 2019 and 2020

Parameter	Unit	Value
Parameter	Unit	0-30	30-60
Mechanical analysis
Sand	%	92.95	93.88
Silt	%	3.75	4.06
Clay	%	3.30	2.06
Texture	Sand
Chemical analysis (soil extract (1:1)
pH		7.90	7.8
Electrical conductivity (ECe)	ds m^-1	1.6	1.3
CaCO₃	%	8.30	6.0
Calcium cations (Ca⁺²)	meq l^-1	1.6	1.0
Magnesium cations (Mg⁺²)	meq l^-1	0.6	1.0
Sodium cations (Na⁺)	meq l^-1	1.0	1.1
Potassium cations (K⁺)	meq l^-1	0.3	0.2
Chloride anions (Cl⁻)	meq l^-1	1.2	1.0
Bicarbonate anions (HCO₃⁻)	meq l^-1	0.3	0.2
Sulfate anions (SO₄⁻²)	meq l^-1	1.8	2.0
Nitrogen available	mg l^-1	13.0	20.0
Organic matter	%	0.01	0.1
Saturation percent	%	22.0	27.0
Each value represents the mean of three replications.

Table 2.a Weather data from the experimental site throughout the period of (January to December) during the 2019 growing seasons.

Element Month	RH (%)	SR (watt/m2/day)	Temperature		Ws (m/sec)	atmospheric Pressure (mbar)	Corrected E pan mm/day	Sun shine hours
Element Month	RH (%)	SR (watt/m2/day)	T max (ºC)	Tmin (ºC)	Ws (m/sec)	atmospheric Pressure (mbar)	Corrected E pan mm/day	Sun shine hours
January	32.5	141.5	23.7	8.06	2.8	993.7	5.46	10.4
February	31.2	163.3	24.8	7.1	3.4	993	5.04	11.1
March	24.4	216.5	28.8	12.8	3.1	991.6	6.44	12
April	21.38	241.5	34.4	17.7	3.5	987.6	8.19	12.9
May	15.3	287	41.3	23.3	3.1	983.9	9.31	13.6
June	17.5	312.2	43.2	27.2	3.1	983	11.34	14
July	17.8	310	42.1	25.8	2.8	981.8	11.2	13.9
August	23.6	231.7	40.8	26.6	2.9	983	11.83	13.2
September	22.9	221.5	36.8	24.5	3.7	984	9.94	12.4
October	20.4	227	37.7	23.8	3.4	986	5.39	11.5
November	33.7	154.4	31.4	16.5	2.7	985	5.39	10.6
December	40.6	135.5	25	10.6	3	993	4.48	10.2

Table 2.b Weather data from the experimental site throughout the period of (January to December) during the 2020 growing seasons.

Element Month	RH (%)	SR (watt/m/day)	Temperature		Ws (m/sec)	atmospheric Pressure (mbar)	Corrected E pan mm/day	Sun shine hours
Element Month	RH (%)	SR (watt/m/day)	T (ºC)	T (ºC)	Ws (m/sec)	atmospheric Pressure (mbar)	Corrected E pan mm/day	Sun shine hours
January	33.12	161	24.32	8.84	2.86	999	5.81	10.4
February	35.38	181.4	25.12	9.42	3.48	994.5	6.99	11.1
March	26.1	213.6	30.86	14.85	2.9	988.4	8.25	12
April	22	244.6	34.15	18.19	3.2	987.5	9.14	12.9
May	19	286	39.6	22.8	3.4	985	9.32	13.6
June	16.6	327	41.55	24.74	3.4	983	9.33	14
July	19.13	309.5	41	25.4	2.9	981	10.16	13.9
August	24.8	230.2	41.3	27.1	2.75	980.9	12.08	13.2
September	20.1	217	36.7	26.6	3.3	982	10.47	12.4
October	17.88	232	36.4	23.7	3	990	5.95	11.5
November	37.14	158.2	32.68	18.3	2.8	990	6.09	10.6
December	43.4	144	26.2	11	3.2	998	5.04	10.2

Max maximum temperature, Min minimum temperature, MS^-1 meter/ second, and mm millimeter. The meteorological data were obtained from Toshka agrometeorological station, Egypt. Values are the mean of replicates ± standard errors

Table 3 The crop evapotranspiration and irrigation water applied for maize at different sowing dates during the growing seasons of 2019 and 2020

		Total
		Total
ET_C (mm)		684.0
The total Ir (m³ ha ^-1) of sowing date (February)	100% Ir (c)	7524.0
The total Ir (m³ ha ^-1) of sowing date (February)	70% Ir	5266.8
ET_C (mm)		1009.6
The total Ir (m³ ha ^-1) of sowing date (March)	100% Ir (c)	13065.7
The total Ir (m³ ha ^-1) of sowing date (March)	70% Ir	9572.5
ET_C (mm)		1224.0
The total Ir (m³ ha ^-1) of sowing date (June)	100% Ir (c)	15840.0
The total Ir (m³ ha ^-1) of sowing date (June)	70% Ir	11088.0
ET_C (mm)		850.0
The total Ir (m³ ha ^-1) of sowing date (August)	100% Ir (c)	11000.0
The total Ir (m³ ha ^-1) of sowing date (August)	70% Ir	7700.0
ET_C (mm)		703.5
The total Ir (m³ ha ^-1) of sowing date (September)	100% Ir (c)	9103.7
The total Ir (m³ ha ^-1) of sowing date (September)	70% Ir	6810.1

ET_C crop evapotranspiration, mm millimeter, m³ h ^-1 cubic meter per hectare, 100% Ir (applying 100% of irrigation water requirements - represent full irrigation level), 70% Ir (applying 70% of irrigation water requirements - represent limited irrigation scheme)

No competing interests reported.

The impacts of climatic changes on the yield and water use efficiency of maize grown under different sowing dates and two irrigation schemes in arid climate

Status:

Journal Publication

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Abstract

Figures

1. Introduction

2. Materials And Methods

3. Results

4. Discussion

5. Conclusion

Declarations

References

Tables

Additional Declarations

Status:

Journal Publication

Version 1