Interaction Effects of Sowing Date, Irrigation Levels, Chitosan, and Potassium Silicate On Yield and Water Use Efficiency for Maize Grown Under Arid Climate

In the south of Egypt, field experiments were conducted during the spring (March) and fall (September) seasons of 2020 and 2021 at the experimental farm of Water Studies and Research Complex station, National Water Research Center, Toshka—City of Abu Simbel which is located at the latitude of 22°, 24′.11′ N longitude of 31°, 35′.43′ E and altitude 188 m. The texture of the experimental soil is sand, and the other main physical and chemical properties are given in Table 1. The main source of irrigation water is groundwater through a well that has been dug into the area under investigation, depending on the quality of the water it has been classified as C₂S₁, and the chemical properties of the irrigation water are given in Table 2.

The experimental site has an arid climate with a daily average temperature ranging from 40 to 45. The meteorological data from March to September in both growing seasons were obtained from the agrometeorological station at Toshka, approximately 100 m from the experimental site. The weather data of the monthly relative humidity (%), T maximum, and minimum temperature (℃) during the 2020–2021 growing season are given in Fig. 1 in the spring and fall. The T max during spring 2020 & 2021 ranged from 33.7 to 43.1 ℃ (39.4 ℃ as mean) and T min was ranged from 16.4 to 24.7 ℃ (21.6 ℃ as mean). While, the T Max for fall 2020 & 2021 ranges from 24.2 to 40.0 ℃ (31.6 ℃ as mean), the T Min was ranged from 8.4–23.3 ℃ (15.8 ℃ as mean).

In order to accomplish the purpose of this study two similar experiments were chosen, and the sowing dates (spring sowing date—Sd1 and fall sowing date—Sd2) were allocated in the main plot, then a strip-plot design with five replicates was used. The vertical plots were allocated to the two irrigation water levels, i.e., 100 and 70%, whereas the horizontal plots were devoted to the four foliar application rates, namely, 0 (control—spray with pure water), 250 (mg l⁻¹) chitosan, 500 (mg l⁻¹) chitosan, 1000 (mg l⁻¹) potassium silicate, 2000 (mg l⁻¹) potassium silicate. The foliar chitosan was sprayed four times every 15-day initiated after 4 weeks of emergence, while potassium silicate (K₂SiO₃) (10% K₂O, 25% SiO₂) as foliar spraying has been applicated three times at 40, 60, and 80, days after sowing. The experimental area of each plot was 5 × 3 m (15 m²) with five lines, the experimental site was irrigated by drip irrigation.

The fertilization recommendations and field practices of the Ministry of Agriculture in Egypt for the newly reclaimed soils were implemented as follows: with the preparation of the soil before sowing phosphorous fertilizer has been added at the rate of 710 Kg ha⁻¹ with calcium super phosphate (15% P₂O₅), while at a rate of 235 Kg ha⁻¹ potassium sulfate (48% K₂O) has applied in three equal portions, at 60, 75, and 90 days of cultivation. Nitrogen as ammonium nitrate (33.5% N) was applied in equal portions on a basis of 950 kg ha⁻¹, it started after 15 days of sowing and was repeated every 3–4 days at a rate of 50 kg per portion until it reached the flowering stage. The cultivar of maize (Zea mays L.) was Triple Hybrid Giza 352, which is resistant hybrid to late wilt, the most appropriate date for planting is during the month of May and lasts until August, and the harvesting takes place 110–120 days after planting. In the Sd1 and Sd2 seasons of 2020 and 2021 maize seeds were sown in hills at a rate of 35 kg ha⁻¹ on the 15th of March and 15th of September, respectively. The maize seeds were sown on one side of the dripper’s jet. The spacing between the plants was 20 cm, the spacing between the rows was 50 cm, and the depth was 5 cm. Two seeds were drilled, and about 2 weeks after emergence, it was thinned to ensure a plant per hill to maintain the population density at 10 plants m⁻² (100,000 plants ha⁻¹).

After 60 days of planting, composite plant samples were taken from each experimental unit to record the plant height, each consisting of five plants. To measure the growing parameters of maize, the three middle rows were harvested. After the border rows were excluded, the plants were harvested to determine the grain yield and yield components: number of ears plant⁻¹, (thousand) grain weight, number of row/ears, ear length, and weight (g).

The individual effect of the treatments for sowing dates, irrigation levels and foliar application rates of Ch and PS (p < 0.05), as well as the interaction effects of sowing dates × irrigation regimes × foliar application rates of Ch and PS (p < 0.05) on maize growth yield characteristics are given in (Table 4 and 5). Regarding the individual effect of the irrigation levels in Sd₁, the results refer to a negative significant effect on most growth characteristics (comparison between C₁₀₀ with C₇₀) except for (ear weight and grain index). In the contrast, the results mention that in Sd₂ there were fluctuated influences, the adoption of Ir₇₀ has positive significant impacts on (ear length, number of ears/plant and number of rows/ear), as seen in (Fig. 2).

By comparing the adoption of the same applications of Ch and PS treatment, it was found that under Ir₁₀₀ in Sd₁, the adoption of the higher concentration rates of Ch caused in significant improvements differences in (plant height, number of ears/plant and number of rows/ear), while under Ir₇₀ there had no significant differences. Likewise, in the Sd₂ season, it was found that under Ir₁₀₀ the adoption of the higher concentration rates of Ch caused significant improvements in (ear length and grain index), while under Ir₇₀ there had no significant differences in growth yield characteristics.

Based on the results illustrated in (Fig. 3a), by comparing the control treatment, the gained results mention that under Ir₁₀₀ planting maize seeds in the Sd₂ caused an increase in grain yield than spring Sd₁ by 29.7%, also it was increased with using Ir₇₀ by 33.0% under the same circumstances.

On the other side, the foliar application of Ch and PS leads to obtaining more enhancement on grain yield than the control treatment under each irrigation level, for instance, in the Sd₁ under Ir₁₀₀ it was raised by 37.2, 80.5, 6.9, and 59.0% for Ch_250, Ch₅₀₀ PS₁₀₀₀ and PS₂₀₀₀ treatments, respectively. In the same context, in the Sd₂ under Ir₁₀₀ it was raised by 17.4, 31.2, 17.4, and 27.7% for Ch_250, Ch₅₀₀ PS₁₀₀₀, and PS₂₀₀₀ treatments, respectively.

By comparing the control treatment, a lower maize yield was obtained with sowing maize seeds in the Sd₁ season, as can be seen in (Fig. 3a). Furthermore, by comparing the application of Ch and PS treatment in Sd₁ under Ir₁₀₀, a higher maize yield was obtained with adopting Ch₅₀₀ in contrast to adopting the other applications. Likewise, in the Sd₂ season, it was found that under Ir₁₀₀ or Ir₇₀, a higher maize yield was obtained with adopting Ch₅₀₀ which was significantly equaled adopting Ir₇₀ × foliar applications of PS₂₀₀₀. In the same context, the superiority of the adoption of the higher concentration rates of Ch and PS under Ir₁₀₀ or Ir₇₀ irrigation level is still pronounced in attaining the highest maize yield in the Sd₁ and Sd₂ except with adopting higher concentration rates of PS in the Sd₁ × the adoption of Ir₁₀₀.

On those grounds, by comparing the control treatment, a lower maize Wue was obtained with sowing maize seeds in the Sd₁ season, as can be seen in (Fig. 3b). Furthermore, the obtained results showed that the highest Wue values were attained by applying Ch₅₀₀ or PS₂₀₀₀ as a foliar application and irrigating maize plants at Ir₁₀₀ in the Sd₂ which caused increases in Wue reach to 30.6% than the control treatment which were significantly equaled applying foliar applications of PS₂₀₀₀ × adopting Ir₇₀ irrigation level for attaining the highest Wue in the second season—Sd₂.

By sowing maize seeds in the Sd₂ and applied Ch₅₀₀ × the adoption of Ir₇₀ irrigation level, caused in increases of Iwue by 63.0% than the control (C₇₀), which allowed to confer irrigation water at par with attained the highest Iwue.

In this respect, adopting Ir₇₀ × foliar applications of Ch_250, PS₂₀₀₀ and PS₁₀₀₀ were significantly equaled control treatment under Ir₇₀ for attaining the lowest Iwue in the Sd₁. Likewise, in the Ir₁₀₀, the adoption of PS₁₀₀₀ applications were significantly equaled the control treatment for attaining the lowest Iwue. In the same context, the results in (Fig. 3c) indicated that the highest Iwue values in the first season were obtained with adopting Ir₁₀₀ or Ir₇₀ irrigation level and applying Ch₅₀₀ applications. While in the Sd_2, it was obtained by adopting the limited irrigation level- Ir₇₀ × foliar applications of Ch₂₅₀ or Ch₅₀₀.

Sowing date constitutes one of the prominent factors that limit maize crop yield and is also a fundamental factor in determining yield. Accordingly, determining the optimum sowing date is considered essential to crop production, as the planting date depends on the temperature since an increase in temperature affects crop yield due a shorter duration of different growing seasons (Harrison et al. 2011; Ahmad et al. 2018). The obtained results indicated that Sd₂ leads to attaining a higher maize yield than the Sd₁, this due to the suitable climatic condition in the fall which allows for maize plants to growing better such as (suitable temperature, humidity, less transpiration, etc), these results are closed to those obtained by (Hassaan 2018; Abaza 2021). In this concern, as the other crops maize plants are susceptible to climate change (high temperature, precipitation, and CO₂), however, the temperature showed more negative impacts on crop yield than other variables (Ottman et al. 2012; Wheeler and Von Braun 2013). Moreover, increased mean temperatures have been shown to reduce the actual growth period between planting date and crop maturity due to accelerated crop development, and although that enhancing filling, the fill rate cannot compensate for these temporal constraints which leads to a decrease in biomass accumulation and yields (Dias and Lidon 2009; Wang et al. 2009; Asseng et al. 2011). Hence, it’s worth noting that the average climatic data which has been recorded in the spring and fall seasons of 2020 and 2021 indicated that the mean maximum and minimum temperatures were (40.0–23.3) in September, (35.9–20.3) in October, (30.4–15.0) in November, and (27.6–11.8) in December, respectively, while it was (33.7–16.4) in March, (38.1–19.3) in April, (40.9–23.5) in May, (41.3–24.3) in June, and (43.1–24.7) in July, respectively, as seen in (Fig. 1). Through the obtained results herein, it’s interesting to point out that at higher temperatures than 32 °C most significant effects occur on starch production and grain weight, resulting in lower fill rate and causing deterioration of the quality of maize cereals (Wilhelm et al. 1999; Siebers et al. 2017), furthermore according to (Waqas et al. 2021) they mention that stress caused by high temperatures limits pollen viability and silk receptivity, resulting in significant reductions in grain yield. In addition, referring to the obtained data that has been recorded for the mean maximum and minimum temperatures in the period from 2005 to 2007 reached (39.4–23.4) in September, (36.8–21.1) in October, (29.2–13.8) in November, and (34.2–18.6) in December, respectively, while it was (31.5–13.2) in March, (36.1–17.8) in April, (39.8–22.7) in May, (41.7–24.3) in June, and (42.3–24.5) in July, respectively. As such it is important to note that simply increasing the average seasonal temperature by 1 °C can reduce the economic production of the maize crop by 3% to 13% (Izaurralde et al. 2011). Thus, through the forgoing clarified the prominent impact of climate change which involves the importance of rearrangement of the common recommendations that related to the optimum sowing dates in south of Egypt and other similar areas.

The obtained data indicated that the adoption of Ir₇₀ provides better maize yield and wue than Ir_100, particularly in the Sd₂ sowing dates. I assumed that attribute to improvements in the yield characteristics, which were in agreement with those obtained by (Atta 2007; Rekaby et al. 2017; Wang et al. 2022). Furthermore, I concluded that with exposing maize plants to water stress in the fall season there were several interrelated factors that could partly ameliorate the impact of these circumstances among them the short span of time which plants have exposed to water stress, viz when the sowing date was shifted from the middle of March to the middle of September this status allowed plants to exceed the negative impact of water shortage by escaping strategy which based on the ability to complete its life cycle after exposure to water shortage as long as that didn’t exceed the critical point at par with availability of suitable climatic conditions for growth in the studying area, in this case, plants do not suffer from water deficiency due they are capable of modulating their vegetative and reproductive phenology according to the most favorable period, which is consistent with (De Micco and Aronne 2012). Moreover, planting maize seeds in the fall works in decreasing the growing period which reaches to 100–110 days approximately, conversely planting maize seeds in the spring the growing season reaches 135–140 days. These reasons are accompanied by the self-ability of maize to cope with short periods of water stress resulting in maintaining the yield profitability at acceptable values in the fall, these findings are in harmony with the study of (Kulczycki et al. 2022).

The current results showed that at Sd₁ & Sd₂ applying Ch and PS as a foliar application on maize plants fulfills pronounced improvements in yield, Wue, and Iwue under full irrigation (Ir₁₀₀) or stress treatment (Ir₇₀). The previous findings attributed to the numerous benefits that Ch and PS confer, this effect has been widely studied among them that Ch has an important effect on plant growth by catalyzing cell growth and development, increasing the activity of key enzymes in nitrogen metabolism, and enhancing nitrogen transfer, leading to increased yield (Guan et al. 2009; Mondal et al. 2013; dos Reis et al. 2019; Mohammadi et al. 2021). On other hand, applying PS not only improved physiological and agronomic features affecting crop growth and yield through optimum treatment of the water supply but has also mitigated the negative impacts of water stress. Generally, the application of PS enhances growth, seed yield, and WUE, thus it is an appropriate management strategy (Eyni-Nargeseh et al. 2022). In this regard, Artyszak (2018) hypothesized that such increases in yield, yield components, and WUE attributed to the promotion of photosynthetic activities and optimal growth conditions in PS-treated plants, moreover Li et al. (2018) indicated that plants treated with silicon produce respectively 35% more biomass and 24% more grain yield than untreated treatment.

Furthermore, the gained results clarified that the favorable impacts were rising steadily by using the higher concentrations of Ch and PS, such findings are in parallel with those obtained by (Chibu and Shibayama 1999; Mondal et al. 2013; Shedeed 2018) they demonstrated that the morphological and the physiological traits, and yield was improved by using the higher rates of foliar Ch and PS. In this regard, (Kamenidou 2005; Wang et al. 2022) recommended that a number of horticultural plants have been improved through supplementation in Si according to the source, the rate, the Si content, and its deposit in plant tissues which varied from one species to another. On the other side, the results point out to the immense improvements in yield by the adoption of Ch₅₀₀ which were superior than the PS₂₀₀₀ under Ir₁₀₀ and Ir₇₀, these findings attribute to the butter solubility of Ch than PS particularly after adjustment pH of Ch by diluting acetic acid, this finding is corroborated by (Almeida et al. 2020).

On the other hand, the obtained results demonstrated that adoption of the higher Ch concentrations in Sd₁, lead to better improving maize yield particularly under Ir₇₀, while the adoption of the higher concentrations of PS in Sd₂, lead to better improving maize yield particularly under Ir₇₀ (Fig. 3a). In this concern, I conclude that in Sd₁ due to the increments of the weather conditions, confer the educated amounts of water within the plant tissues are considered a crucial factor, while in Sd₂ the main crucial factor is the reduction of the growing season (90–100 day). Therefore, with the adoption of the higher Ch concentrations under Ir₇₀ although plants have severed of increasing climate conditions, it appears that Ch applications form a transparent layer reducing perspiration, which in turn worked on the maintenance of water within the tissues of plants that was useful for the mitigation of harmful effects of the reduction in soil moisture (Roychoudhury et al. 2022). Therefore, the multiple features of Ch₅₀₀ work on ameliorating unfavorable effects of water stress in growth and yield, these findings are parallel to those obtained by (Malerba and Cerana 2015; Hidangmayum et al. 2019). Whilst, it appears that the adoption of higher PS applications in Ir₇₀ treatment at (Sd₂) attained better yield. In this context, I hypothesized that in Sd₂ the higher humidity rates seems it worked on in more improvements in PS solubility, which perform some features such as improving the nutrients transportation and accumulation, which has led to the enhancements of yield.

From the foregoing, the impacts of Ch &PS applications on maize plants sowing in spring or in fall sowing dates and exposure to water stress were clear. It’s quite important noted that the obtained results indicated the positive impact of identify the optimum sowing dates and irrigation level. However, there are some obstacles facing that such as (the competition between crops, insects and diseases). The obtained results recommended sowing maize during the fall season, which will lead to the inability to sow an important crop (i.e., wheat, barley, faba bean etc.). Therefore, the competition between crops on the available cultivation area remains the main limitation, thus I suggest that the better crop for sowing will be identified, in accordance with the highest wue. Furthermore, by sowing maize during the fall season, as humidity increased, more insects and diseases arose, particularly fall armyworm insect. Where maize is the preferred host for fall armyworm insect in the countries (Rashed et al. 2022). It can decrease annual maize yield from 21% to 53% without control methods (Huang et al. 2020). However, in the current study noticed that it’s appearance and damage was more detected in the spring season. On the other side, regarding the enhancing of the diseases during the fall season, the current study noticed that the Ch &PS applications enhance maize tolerance. In this concern, Kocięcka and Liberacki (2021) demonstrates that this Ch is very effective against diseases and pathogens that are most dangerous to cereals, which have been broadly emerging at the Sd₁ than Sd₂.