Introduction

A C4 crop with a high energy content, sorghum (Sorghum bicolor L. Moench) is distinguished by its short growth cycle, high biomass output, and resilience to stress1. Sorghum is a multipurpose annual plant species. It is a good source of sugar, grain, and fodder. Sorghum can be grown for fodder and as broomcorn in addition to being a grain that is regarded as the fifth most important crop after wheat, rice, maize, and barley2,3. When compared to other crops in the cereal family, sorghum is a serious crop that can withstand drought well4. Although sorghum is a staple crop in dry and semi-arid areas of the world, water stress frequently affects it before and after blooming, which can drastically impair grain output5. Though there are notable differences between their methods of use, sorghum and maize are comparable in terms of feed quality and commercial worth. Although sorghum can be eaten in a variety of ways, including silage, wet forage (high moisture green fodder), dry fodder (hay), and direct grazing as pasture or after livestock collect it, silage is the most common way that maize is eaten6. Additionally, compared to maize, sorghum is a more economically advantageous crop due to its potential to be harvested as a crop with many cuttings7. Sorghum’s ability to readily adapt to a variety of agroecological situations is one of its most significant benefits. It is a significant crop for bioenergy and a great supplement to ruminant diets. Due to its great degree of drought and temperature tolerance, forage sorghum can provide large amounts of food with fewer resources8. Recent statistics show that sorghum was cultivated on almost 40.73 million hectares worldwide in 2025/2026, with 0.15 million hectares in Egypt. Egypt had a high potential yield, with an average yield of more than 5.20 metric tons ha-1 compared with a worldwide 1.54 metric tons/ha9.

The substantial discrepancy between the actual average yield that farmers acquire on their fields and the prospective or attainable fodder yield (what can be reached with the optimum agronomic practices and appropriate varieties) is known as the sorghum fodder yield gap. This disparity is frequently significant, suggesting a sizable chance to boost output. Assefa et al.10 shown that despite an increase in yield potential brought about by advancements in agronomy or hybrid creation, there is a significant yield gap in sorghum and a significant year-to-year variance in yields. Potential and achievable on-farm water-limited yields differ significantly11. The actual yield (based on USDA statistics) and the projected non-irrigated yield were found to differ by 66 to 96%. Timely planting and optimal maintenance of study plots, which are challenging for producers to reproduce when farming a vast region, are partly responsible for this yield disparity10. With an average global actual yield of 1.4 to 2.5 tonnes per hectare (t/ha) compared to theoretical yields that can reach over 12 t/ha under ideal circumstances, the global yield gap for sorghum is significant and extremely varied by area9. Evidence regarding the contribution of cultivar-specific characteristics to yield stability under varying soil water retention capacities, such as plant height, tillering capability, and dry matter content, is still lacking. In areas where climate unpredictability is becoming more prevalent, closing this gap is essential to maximizing sorghum production as a sustainable fodder supply12. Significant yield variability in rainfed environments is caused by agronomic practices, water scarcity, and irregular rainfall patterns, particularly during crucial growth times.

Crop stability and productivity are seriously threatened by climate variability, especially by changing precipitation and warming temperatures13. Plant growth requires water, and one of the biggest obstacles to crop productivity is drought14. A common abiotic stressor that restricts crop development and productivity, drought has a major effect on ecosystems, agriculture, and food security15. According to recent research, crop physiology activities are significantly hampered by drought stress at several developmental growth phases. This delays maturation and results in significant production losses16. One important factor is drought. A key tactic for maintaining increased yields is improving drought resistance, with an emphasis on creating cultivars that can withstand drought17. Numerous elements of plant growth, including as plant height, fresh and dry weight, leaf number, leaf area, root length, and number of root systems, are suppressed by drought stress, according to earlier research17,18,19.

One well-known crop type that can withstand drought is sorghum, and sorghum landraces have unique alleles that let them adapt14. In areas vulnerable to climatic stress, sorghum is a promising crop for future food and feed security because of its resilience and drought tolerance13. Sorghum’s diploid genomic structure and effective photosynthetic system make it a great crop that can withstand drought20. According to Tsehaye et al.5, different genotypes of sorghum react differently to drought stressors before and after blooming.

Agronomic techniques like planting and irrigation have a big influence on plant yields. For optimal crop production, planting procedures should be modified based on soil types and climate changes. The crop can thrive in later stages of crop growth and development when the right planting technique is used21,22. Insufficient land availability, improper timing and techniques for sowing, a shortage of high-quality forage seeds, poor irrigation and nutrition management, weed infestation, insufficient plant protection, etc. are the primary reasons for low forage production23. The production and quality of biomass are significantly impacted by management factors, such as planting techniques and the cultivation of appropriate cultivars. The final grain and biomass yield of maize and sorghum are impacted by improper sowing techniques such as broadcast and flat sowing, which lead to poor germination and stand establishment24. Consequently, compared to traditional sowing techniques, improved planting techniques such as ridge and bed sowing enhanced seed germination and assisted plants in making better use of light, land, and other inputs25. Additionally, because of the proper soil conditions, ridge and raised beds enhance root growth, which significantly boosts water and nutrient uptake and increases maize biomass output26. Compared to traditional broadcasting and line sowing, ride and bed sowing significantly boosted the grain and dry matter productivity of maize27. While the furrow serves as a planting belt, collects precipitation that falls directly on the surface belt, and receives runoff from the ridges, ridges are crucial for collecting rainwater28. The crop’s microenvironment can be directly impacted by different planting techniques, which can then affect the crop’s growth characteristics and yield components29. The previous literature reviews present clear hypotheses regarding the importance of this study in addressing the problem of water scarcity.

Since these procedures are required to increase forage yield and water use efficiency, it is essential to comprehend the complex interactions between environmental factors and planting techniques under normal irrigation and drought conditions to maximize sorghum forage yield. Therefore, under normal irrigation and drought conditions, the current field experiments were conducted to examine the effects of seasons, locations, and planting techniques (drill in row, broadcasting, and hole farming) on the growth, forage yield and water use efficiency traits (in both fresh and dry) of sorghum in Egypt.

Materials and methods

Experimental design and treatment details

Seeds of the Sorghum Hendy variety (Hybrid Sorghum Mecca) were imported from India. Under normal irrigation and drought conditions, separate field experiments have been carried out in the 2023 and 2024 growing seasons at the two private farms in Ras El Hikma at East of Marsa Matrouh City (Latitude 27°52 × 29.6” N and Longitude 31°05 × 21.4” E) and Wadi El-Raml at West of Marsa Matrouh City (Latitude 27°09 × 13.1” N and Longitude 31°16 × 17.8” E), Matrouh Governorate, Egypt. Identifying the best planting methods (hole farming, drill in row, and broadcasting) for the Sorghum Hendy variety in terms of growth, forage yield, and water usage efficiency attributes in both growing seasons and locations under normal and drought conditions was the aim of this study. In each experiment, sorghum seeds were planted under three planting methods in a randomized complete block design with three replications. Each experimental unit measured 15 by 40 (400 m2), with a row spaced 20 cm apart and a hole spaced 10 cm apart. Each subplot included two border rows and a buffer gap of 2 m between neighboring plots to reduce treatment overlaps and positional bias. Planting took place on May 15 and 20 of the 2023 and 2024 growing seasons, respectively. Each fed had a seed rate of 20 kg. A drip irrigation system was used to plant sorghum. During the aforementioned sowing dates, sorghum seeds were planted in hills (about five seeds per hill) in the two furrow ridges, covered with sand, and then immediately irrigated. The normal and drought experiments for each season and location were irrigated with water amounts of 2200 and 2000 m3 per fed, respectively. To reduce environmental fluctuations as much as possible, all agronomic procedures were followed, and the crop was sown in a single day under consistent field conditions. The first, second, and third cuts were taken after 50, 180, and 105 days after the sowing date, respectively. Using established procedures by Page et al.30, Table 1 displays the findings of soil analysis for 0–30 cm depth prior to planting at Ras El Hekma and Wadi El-Raml sites, Matrouh Governorate, Egypt, in two growing seasons (2023 and 2024).

Table 1 Some chemical properties of soil samples of the surveyed sites.
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Irrigation water applied (IWA)

The daily reference evapotranspiration (\(\:{ET}_{o}\)) values were estimated based on FAO Penman-Monteith method using the latest five-year average of weather data from the meteorological station at two locations, where our experiment was conducted31. The crop water requirements expressed as crop evapotranspiration (\(\:{ET}_{c}\); mm d− 1) according to the Allen et al.31 equation was calculated as follows:

$$\:{ET}_{c}={ET}_{o}x{K}_{c}$$

where, \(\:{ET}_{o}\) and \(\:{K}_{c}\), denotes evapotranspiration (mm d− 1) and crop coefficient value, respectively, which differs from one growth stage to another as described by Allen et al.31 and Brouwer and Heibloem32. The amount of IWA per experimental plot during the irrigation regime was computed following the equation given by Allen et al.31 as follows:

$$\:IWA\left({m}^{2}\right)=\frac{{ET}_{c}xAx{I}_{i}}{Eax1000x(1-LR)}$$

where \(\:{ET}_{c}\), A,\(\:\:{I}_{i}\), Ea, and LR, respectively, are the crop water requirements (mm d− 1), experimental plot area (m2), irrigation intervals (d), efficiency of irrigation system, which was considered 0.6, and leaching water requirements.

Using one PVC (polyvinyl chloride) pipe (50 mm diameter × 1 m length) for each plot, the IWA was transferred to cover the whole plot surface area. The irrigation water quota transferring across each PVC pipe for each plot was calculated following the equation given by Israelsen and Hansen33 as follows:

$$\:Q=\frac{CA\sqrt{2gh}}{1000}$$

where Q, C, A, g, and h, are the irrigation water discharge (l s− 1), discharge coefficient, PVC pipe’s cross section area (cm2), gravity acceleration (cm s− 2), effective head of water (cm) over the center of piper making flow free, respectively. A guard border of 2 m width between the adjacent experimental plots was in each replication to avoid the border effects. Likewise, another one with 5 m width as a separator under two irrigation treatments (2200 and 2000 m3 fed− 1) was maintained to avoid water infiltration from one to another treatment.

Measurements of studied traits

To determine the plant height (cm), number of tillers/m2, fresh weight (ton/fed), and dry weight (ton/fed) under normal irrigation and drought circumstances, one square meter was randomly selected from each plot, and the two cuts were taken after the first. Every cut was picked by hand. Once the fresh weight of the complete sample was recorded in the field, two kilograms were taken as a subsample and divided into leaf and stem. The dry weight of the plant components was measured following three days of oven drying at 80 °C. Fresh and dry water use efficiencies (kg/m³) were calculated by dividing the fresh and dry forage yield (kg/fed) by the amount of water received in both growing seasons (m³/fed), respectively34, according to the following equations:

$$\:Fresh\:water\:use\:efficiency=\frac{Fresh\:forage\:yield\:(kg/fed)}{Wster\:volume\:({m}^{3}/fed)}$$
$$\:Dry\:water\:use\:efficiency=\frac{Dry\:forage\:yield\:(kg/fed)}{Wster\:volume\:({m}^{3}/fed)}$$

Statistical analysis

The assumptions of normality and homogeneity of variances were verified before performing the analysis. A three-way ANOVA test and the coefficient of variation (CV%) were applied to the measured data in accordance with Steel and Torrie35 approach in order to detect any notable differences in the influence of the experimental components and their interactions. The means at p < 0.05 were compared using the least significant difference (LSD) test. Small letters were used to compare the column means. Gomes36 states that the CV% estimates were separated into four groups: low (CV < 10%), moderate (10%< CV ≤ 20%), high (15.0% ≤ CV ≤ 21.0%), and extremely high (CV ≥ 21%). Fernandez37 method was used to calculate the stress tolerance index (STI) for fresh and dry forage yields across the experimental factors under normal \(\:{(Y}_{p})\)and drought \(\:{(Y}_{s})\:\)conditions, as follows: \(\:STI={(Y}_{p}\times\:{Y}_{s})/{\left({\stackrel{-}{Y}}_{p}\right)}^{2},\) where \(\:{\stackrel{-}{Y}}_{p}\) indicates the mean of all factors in normal conditions. To further understand the relationship between the experimental treatments and the qualities being studied, principal component analysis (PCA) was employed. The ANOVA and PCA were performed using SPSS version 20 and OriginPro 2025b 10.2.5.212, respectively.

Results

Seasonal weather

Figure 1 displays climate data from April to September across the two growing seasons and locations. Differences in mean temperature, total precipitation, and average relative humidity resulted in significant variations between the two years and between the locations under study. Furthermore, we noted severe occurrences of unevenly distributed rainfall in both seasons and locations, as well as significantly higher mean temperatures and average relative humidity during the 2024 growing seasons and at the Wadi El-Raml location under study. Both growing seasons also had higher average temperatures, total precipitation, and average relative humidity in the Wadi El-Raml location compared to the Ras El Hekma location. August had higher temperatures for both growth seasons and locales. April saw lower temperatures in both growing seasons and regions. The highest average relative humidity was noticed for July at the Ras El Hekma location in both growing seasons, and for June and April at the Wadi El-Raml location during the 2023 and 2024 growing seasons, respectively. The lowest average relative humidity was observed for April at the Ras El Hekma location in both growing seasons, and for September and May at the Wadi El-Raml location during the 2023 and 2024 growing seasons, respectively. In both growth seasons and localities, April had the greatest total precipitation. At both locations, overall precipitation during the 2023 growing season was higher than during the 2024 growing season.

Fig. 1
figure 1

Climatic data at Ras El Hekma and Wadi El-Raml locations, Matrouh Governorate, Egypt, in the 2023 and 2024 growing seasons.

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Analysis of variance (ANOVA)

The ANOVA data for plant height, No. of tillers, forage yield (both fresh and dry), and water use efficiency (both fresh and dry) at all cuts under normal irrigation and drought conditions are presented in Table 2. The ANOVA revealed significant variation (P < 0.05 or 0.01) between the main effects of seasons and locations for plant height at the first, third, and mean cuts under normal conditions and at the first and mean cuts under drought conditions; and for the number of tillers, fresh forage yield, dry forage yield, fresh water use efficiency, and dry water use efficiency traits at all cuts in both conditions. The location factor had a highly significant variation for plant height at the third cut under drought conditions. The study showed significant differences (P < 0.05 or 0.01) in the planting methods for all studied traits at all cuts in both conditions, except plant height at the second cut and fresh forage yield and fresh water use efficiency at the first cut under drought conditions, which had insignificant differences.

The interaction of seasons x locations was significant (p < 0.05 or 0.01) under normal and drought conditions for plant height at the first, third, and mean cuts, and for fresh forage yield, dry forage yield, fresh water use efficiency, and dry water use efficiency at the second and third cuts. While number of tillers/m2 had an insignificant difference at all cuts under normal and drought conditions. The effects of the season x planting methods interaction were significant (p < 0.05 or 0.01) for plant height at the third cut under normal conditions and at the third and mean cuts under drought conditions; for dry forage yield and dry water use efficiency at the second and third cuts under normal conditions and at the first, third and, mean cuts under drought conditions; and for dry water use efficiency at the total of the three cuts under drought conditions. At the same time, the number of tillers/m2 and fresh forage yield had an insignificant difference at all cuts under normal and drought conditions. The interaction between locations and planting methods was significant (p < 0.05 or 0.01) for No. of Tillers\m2 at the second cut under normal and drought conditions; for fresh forage yield and Fresh water use efficiency at the third cut under normal conditions; and for dry forage yield and dry water use efficiency at the second and third cuts under normal conditions and at all cuts except the second cut under drought conditions. In contrast, plant height showed no significant difference at all cuts under both normal and drought conditions. Significant interactions among seasons, locations, and planting methods were observed on plant height at mean cut under normal conditions and at the third and mean cuts under drought conditions; on fresh forage yield and fresh water use efficiency at the third cut under normal conditions; on dry forage yield and dry water use efficiency at the second and third cuts under normal conditions and all cuts under drought conditions except the second cut. In comparison, the number of tillers/m2 had an insignificant difference at all cuts under normal and drought conditions.

Low coefficients of variation (CV%) were noticed for all studied traits at all cuts, which were less than 10%, except for plant height at the second cut during normal (17.73%) and drought (24.68%) conditions, for fresh forage yield and fresh water use efficiency at the third cut (10.09%) under drought conditions, and for dry forage yield and dry water use efficiency at the second (19.55%) and third (12.00%) cuts under drought conditions. The lowest CV% value (1.62%) was found for the plant height at the mean of the three cuttings.

Table 2 ANOVA test (p-values) for the effect of the seasons, locations, and planting methods on studied traits of sorghum at the three cuts as well as the mean and total of the three cuts under normal irrigation and drought conditions.
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The main effects of experimental factors

The main effects of seasons, locations, and planting methods at all cuts for all studied traits under normal irrigation and drought conditions are presented in Table 3. The highest plant height and No. of tillers/m2 were obtained in 2023 growing seasons at all cuts in both conditions, while the highest values for forage yield and water use efficiency (both fresh and dry) traits were observed with 2024 growing seasons at all cuts, except the second cut in both conditions. As for studied locations, all studied traits at all cuts in both conditions increased in Wadi El-Raml than in Ras El Hekma, except No. of tillers/m2 at the first cut and forage yield and water use efficiency (both fresh and dry) at the second cut. Compared with other planting methods, the hole farming method enhanced all the studied traits at all cuts under normal irrigation and drought conditions. The hole farming method produced the highest forage yield and water use efficiency of sorghum, followed by drill-in-row and broadcasting methods at the three cuts, as well as the mean and total of the three cuttings in both conditions. Under every planting method in both seasons and locations, every attribute that was examined at the first cut performed better than the second and third cuts in both conditions. Drought conditions reduced all studied traits at all cuts compared with the normal irrigation conditions.

Table 3 The main effect of seasonal changes, locations, and planting methods on studied traits of sorghum at the three cuts as well as the mean and total of the three cuts under normal irrigation and drought conditions.
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The first-order interactions effects

The interaction between the 2024 season and the Wadi El-Raml location accounted for more positive effects of all studied traits at most cuts in both irrigation conditions than the other season and location interactions did (Table 4). The highest values of growth, forage yield, and water use efficiency (both fresh and dry) traits at all cuts were recorded in the Wadi El-Raml location at both seasons under both irrigation conditions, except for plant height at the second cut under drought conditions and for No. of Tillers/m2 at the first cut in both conditions. Wadi El-Raml location in the 2024 growing season increased plant height, forage yield, and water use efficiency (both fresh and dry) traits at all cuts in both irrigation conditions, except plant height at the third (normal) and second cuts (drought), forage yield, and water use efficiency (both fresh and dry) traits at the second cut in both conditions. While the Wadi El-Raml location in the 2023 growing season increased No. of Tillers\m2 at all cuts in both irrigation conditions, except at the first cut. Drought conditions reduced all studied traits at all cuts compared with the normal irrigation conditions according to the interaction between seasons and locations. Generally, our results indicated that increasing the forage yield and water use efficiency (both fresh and dry) of sorghum with the Wadi El-Raml location in both growing seasons under normal irrigation and drought conditions.

Table 4 Seasonal changes vs. locations for studied traits of sorghum at the three cuts as well as the mean and total of the three cuts under normal irrigation and drought conditions.
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Regarding the interaction between seasons and planting methods, the hole farming method showed the highest values for growth, forage yield, and water use efficiency (both fresh and dry) traits in both growing seasons at all cuts under normal irrigation and drought conditions. This was followed by the drill-in-row method and the broadcasting method, as shown in Table 5. Except for the third cut and the average of the three cuts, the hole farming approach produced the highest plant height and number of tillers/m2 attributes over the 2023 growing season at all cuts under both irrigation regimes. While, except for the second cut, the hole farming method produced the highest forage yield and water use efficiency (both fresh and dry) traits during the 2024 growing season at all cuts under both irrigation regimes. Drought conditions reduced all studied traits at all cuts compared with the normal irrigation conditions according to the interaction between seasons and planting methods. Generally, our results indicated that increasing the forage yield and water use efficiency (both fresh and dry) of sorghum with the hole farming method in both growing seasons under normal irrigation and drought conditions.

Table 5 Seasonal changes vs. planting methods for studied traits of sorghum at the three cuts as well as the mean and total of the three cuts under normal irrigation and drought conditions.
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Regarding the relationship between locations and planting methods (Table 6), an Wadi El-Raml location at all cuts under both irrigation conditions produced the greatest outcomes for growth, forage yield, and water use efficiency (both fresh and dry) traits of sorghum across the three planting methods under study. Additionally, under normal irrigation and drought conditions, the hole farming approach yielded the greatest values for all examined traits, followed by the drill-in-row method and the broadcasting method at all cuttings in both locations. Compared with other interactions of locations and planting methods, the maximum values for all studied traits were found by the hole farming method across the Wadi El-Raml location at all cuts in both irrigation conditions, except for plant height at the second cut in drought conditions, for No. of Tillers\m2 at the first cut in both conditions, for forage yield, and water use efficiency (both fresh and dry) traits at the second cut in both conditions. Drought conditions reduced all studied traits at all cuts compared with the normal irrigation conditions according to the interaction between locations and planting methods. Every first-order interaction showed a range of patterns. However, statistical analysis revealed that for the majority of the features under investigation at all cuts, the 2024 growing season’s hole farming method with Wadi El-Raml location yielded the greatest values for these traits.

Table 6 Locations vs. planting methods studied traits of sorghum at the three cuts as well as the mean and total of the three cuts under normal irrigation and drought conditions.
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Stress tolerance index (STI)

The STI of fresh and dry forage yields (t/fed) traits of sorghum plants at all cuts affected by the seasons, locations, and planting methods are given in Fig. 2. In comparison to alternative planting methods, the sorghum plants grown by the hole farming approach showed greater STI values at all cuttings throughout all seasons and locales for both fresh and dry fodder yields. Under the planting practices and growing seasons, the STI rose for fresh and dried forage yields at all cuts in Wadi El-Raml locations when compared to the Ras El Hekma location. Generally, the STI was highest for the sorghum plants grown using the hole farming method at the Wadi El-Raml location in both growing seasons.

Fig. 2
figure 2

Stress tolerance index for fresh and dry forage yields (t/fed) traits at all cuts as affected by the seasons, locations, and planting methods.

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Principal component analysis (PCA)

The PCs formed were equal to the number of traits under study, but the four PCs accounted for 100% of the total variation among traits under experimental factors at the mean of the three cuts under normal irrigation and drought conditions, as shown in Table 7. PCA indicated PC1 extracted 90.50% of the total variation among the studied variables with an eigenvalue > 1 under both irrigation conditions. While the other three PCs had eigenvalues < 1. The largest contribution to the overall variation in this study was PC1, which was followed by PC2 (6.22%), PC3 (2.85%), and PC4 (0.43%). PC1 and PC2 extract 96.72%. PC1 and PC2 contributed to all studied traits at the mean of the three cuts with values ranging from 0.28 to 0.30 and from − 0.37 to 0.44, respectively. Also, PC1 exhibited a positive correlation with the hole farming method (1.60) at Wadi El-Raml location (0.74) in the 2024 growing season (0.18). PC2 is associated with the hole farming method (0.59) at Ras El Hekma location (0.77) in the 2023 growing season (1.47).

PC1 and PC2 for the experimental factors and all studied traits at the mean of the three cuts under normal irrigation and drought conditions are displayed in Fig. 3. Every trait examined showed variability as a result of changes in planting methods at locations throughout the course of the growing years, as illustrated by the biplot diagram. All traits exhibited a steep angle between them and showed a positive correlation with experimental factors at the mean of the three cuts under both irrigation conditions, as indicated by the biplot diagram between PC1 and PC2. A perfect positive correlation (angle = 0) was noticed between fresh forage yield and fresh water use efficiency traits, between dry forage yield and dry water use efficiency traits under normal conditions, as well as between fresh forage yield and dry forage yield, and between fresh water use efficiency and dry water use efficiency under drought conditions. Also, all other possible pairs among all studied traits showed a positive correlation in both irrigation conditions.

According to the first two components obtained using PCA, Fig. 3 shows the distribution of experimental factors along different ordinate axes as well as the distribution of different traits among the experimental factors under both normal irrigation and drought conditions. The importance of these characteristics for the corresponding experimental factors is indicated by the experimental factors’ placement along each vector. The hole farming method (first quarter) with Wadi El-Raml locations and the 2024 growing season (fourth quarter) displayed importance for forage yield and water use efficiency traits in both irrigation conditions, which were positively related to PC1. In general, the dry forage yield and dry water usage efficiency of sorghum under normal irrigation conditions were close to the hole farming approach.

Table 7 Results of PCA in the first four PCs for the studied traits of Pearl millet at the mean of the three cuts as affected by the three experimental factors.
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Fig. 3
figure 3

The relationships between the studied traits at the mean of the three cuts across the growing seasons, locations, and planting methods under normal (blue color) and drought (brown color) conditions using the biplot diagram between PC1 and PC2.

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Discussion

In the Mediterranean, where the consequences of climate change are evident, agricultural production is significantly impacted. Recent models indicate greater temperatures and less precipitation, with the trend likely to be particularly pronounced during the years hottest times38. One of the main factors restricting crop growth and productivity is drought. With a focus on creating cultivars that can withstand drought, improving drought resistance is a crucial tactic to maintain increased yields17. In this study, the Sorghum Hendy variety was selected as experimental material to evaluate the growth, forage yield, and water use efficiency (in fresh and dry) in two locations, Matrouh Governorate, Egypt, using three planting techniques in each of the growing years 2023 and 2024 under normal irrigation and drought conditions.

Based on the ANOVA test, growth, forage yield, and water use efficiency (in fresh and dry) at most cuts were affected significantly by seasons, locations, and planting methods under normal irrigation and drought conditions. The year had a substantial impact on the yield of dry forage39, green fodder, and dry matter13. Ertekin and Yılmaz40 found no significant effect of year on fresh forage yield or dry matter yield. These results indicate a significant effect of location on fodder yield, which varied with the location of evaluation41. Locations differed significantly in terms of fresh and dry forage yield, plant height at the two cuts and three cuts, and total sorghum yield42 and on plant height and forage yield of sorghum43. Planting methods significantly affect growth, yield, and quality of forage crops44, fresh forage yield and dry matter yield40, plant height, number of tillers/m2, yield of fresh and dry forage at each cut, as well as the total yield of fresh and dry forage in the first and second summer seasons45, and biomass yield of sorghum28. These results suggest that there is diversity among the experimental elements being studied, which suggests that sorghum’s water use efficiency and fodder productivity at all cuts can be improved under drought conditions. According to Dolapčev Rakić et al.13, the variations in growing seasons are a reflection of the impact of different climatic circumstances and increase the characteristics’ reliance on environmental factors. The results of Erdurmus et al.43, and Ertekin and Yılmaz40, Mekasha et al.46 and Rady et al.42, on growth, fresh and dry forage yields at the cuts, and total forage yield were comparable to the data gathered from the interaction between experimental factors for the current study. This response might possibly have been influenced by the growing season’s environmental circumstances47. The results of CV% would imply that the experimental factors under investigation differ significantly from one another for forage yield and water use efficiency of sorghum at all cuts under drought conditions. Plant height (11.11% and 10.43%), green fodder yield (31.25% and 38.11%), and dry matter yield (41.06% and 51.81%) all showed high CV% values in both growth seasons, according to Dolapčev Rakić et al.13.

Our results showed that drought stress conditions reduced all examined traits at all cuts in both seasons and locations compared with the normal irrigation conditions. Sorghum plant height and fodder productivity were gradually reduced by drought stress48. According to Hussein et al.49, irrigated fodder may benefit from a moderate amount of inadequate irrigation as a water management approach, particularly in regions with limited water supplies. Consequently, a more effective and sustainable method of water use may be achieved by irrigating a greater area with the water saved by deficit irrigation. All of the traits that were analyzed at the first cut outperformed the second and third cuts under all planting methods in all locations and seasons.

Compared to the 2023 growing season, the 2024 growing season saw increases in fresh forage yield, dry forage yield, fresh water use efficiency, and dry water use efficiency at the sum of the three cuttings of 3.59%, 5.21%, 3.59%, and 4.30% under drought conditions, respectively. In contrast, the 2023 growing season produced the maximum plant height and number of tillers/m2 at all cuts under both conditions. These findings concur with those of Dolapčev Rakić et al.13, who found that, possibly as a result of improved environmental circumstances, one of the growing seasons was generally more favorable for biomass and yield features such as plant height (0.85%), green fodder production (8.28%), and dry matter yield (12.14%). Compared to grain sorghum, forage sorghum has a higher base temperature, more leaf area, and a stronger tolerance to heat and water stressors50. Temperature affects yields because greater mineralization rates in warmer climates increase the nutrient’s availability51. Our findings are consistent with those of Druille et al.50 and Pembleton et al.52, who found that raising the mean annual temperature scenario without altering the yearly precipitation increased the yield of feed sorghum. All studied traits at most cuts raised in the Wadi El-Raml location more than in Ras El Hekma location in both irrigation conditions. At the sum of the three cuttings, the Wadi El-Raml location experienced improvements in fresh forage yield (6.62%), dry forage yield (8.04%), fresh water use efficiency (6.56%), and dry water use efficiency (7.18%) under drought conditions, in comparison to the Ras El Hekma location. The yield of forage sorghum is greatly influenced by the site of its cultivation. Plant development, maturity, and nutritional value can be influenced by a variety of factors, including soil type, altitude, and climate (temperature, rainfall, and sunlight). Additionally, different places may have differing degrees of disease and insect pressure, which could affect the total productivity of forage sorghum.

Under normal irrigation and drought conditions, the hole farming method improved all the traits under study at all cuttings when compared to alternative planting methods. Under drought conditions, the hole farming method outperformed the drill-in-row and broadcasting in terms of fresh forage yield (2.55% and 5.42%), dry forage yield (3.05% and 7.33%), fresh water use efficiency (2.54% and 5.42%), and dry water use efficiency (3.03% and 6.50%) at the total of the three cuttings, respectively. Plant height is significantly influenced by planting methods. Reduced plant density, improved light penetration, and efficient soil moisture and nutrient usage are the reasons given for the increased growth with pit techniques53. Our results are consistent with those of Chattha et al.24, Haggag et al.54, and Hssan et al.55, who found that the broadcasting method produced the lowest fresh forage yields, while the hills/ridge seeding method produced the highest. Additionally, EL-Gaafarey et al.45 found that, when compared to broadcasting on the top of the rows, planting in hills on top of the rows resulted in the greatest significant increase in plant height, number of tillers/m2, and yield of fresh and dry forage at each cut as well as the total yield of fresh and dry forage (ton fed-1) in both seasons. Plant growth, which was influenced by competition between plants for nutrients, moisture, sunlight, and other growth factors, was more favorable when planting in hills on top of the rows, which may account for this rise45. In comparison to the traditional flatbed planting approach, Wondimu et al.56 discovered a 15–24% increase in seasonal soil moisture content with tied and open ridges.

By comparing the means under normal and drought stress circumstances, the STI is utilized to identify high-tolerance genotypes37. The sorghum plants cultivated at the Wadi El-Raml location using the hole farming method in both growing seasons reported the highest STI for fresh and dry forage yields at all cuts in both seasons and locations when compared to all other experimental factors in our study. As a result, the forage yield at all cuts of sorghum plants grown using the hole farming method was the least vulnerable to drought stress. Sorghum genotypes that fared well under stress treatment were classified as high-tolerant, and those that fared poorly were classified as sensitive, according to STI value57.

Combining the techniques of PCA and correlation allows for the identification of significant factors influencing folder yield and water use efficiency. PC1 and PC2 account for almost 96.72% of the total variance in all the variables analyzed under the seasons, locations, and planting methods at the mean of the three cuts under normal and drought conditions. Consequently, the results of PC1 and PC2 can be utilized to summarize the original variables in any further data analysis, as well as to explain the overall variance and the PC collection. Nearly 90.50% of the variability in the measured data for the original variables was explained by PC1, with eigenvalues higher than one. A substantial amount of the variability is present in the first principal component, while the second and subsequent components show less variability58. According to Hair et al.59, PCs were deemed significant and valuable if their component loadings were more than ± 0.3 and their eigenvalues were greater than unity. These findings suggested that PC1 was influenced by the hole farming method for forage yield and water use efficiency of sorghum in both irrigation conditions. An estimate of the correlation between the trait vectors is provided by the cosine of the angle between them in the PCA biplot60. The approximate angles of the vectors and the contribution of the same trait pairs in the PCA biplot roughly match the correlations between trait pairs61. In both irrigation conditions, every pair of forage yield and water use efficiency (in fresh and dry) that could be found exhibited a positive connection. According to these findings, choosing these characteristics would help boost the potential fodder production and water use efficiency of sorghum. Positive correlations were found between plant height and number of tillers/m262 and between forage yield and plant height under stress63,64.

The significance of the characteristics under investigation as the primary contributing traits for sorghum’s forage yield and water use efficiency during drought conditions was shown using PCA based on the phenotypic correlation. In general, the Sorghum Hendy variety grown using the hole farming method with the Wadi El-Raml location in both growing seasons provided the highest forage yield and water use efficiency (in fresh and dry) of sorghum in the Matrouh Governorate, Egypt, according to the statistical analysis of the relationship between the variables examined.

Conclusions

Different growing seasons, locations, and planting methods significantly impact growth, forage yield, and water use efficiency in both fresh and dry at most cuts under normal and drought conditions. Raised the hole farming method generally produces the highest forage yield and water use efficiency at total cuts, followed by the row method, while broadcasting results in the minimum values. The highest forage yield and water use efficiency (in both fresh and dry) at all cuts were obtained from hole farming method in the Wadi El-Raml location under both irrigation conditions. Therefore, the hole farming method came to the fore in terms of forage yield and water use efficiency and is more effective under drought stress conditions, which can be recommended to achieve higher forage productivity of the Sorghum Hendy variety when water is scarce in Matrouh Governorate, Egypt.

Future research should focus on identifying and implementing strategies to increase exploitable yield in water-limited cropping regions.