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ISSN : 2287-5824(Print)
ISSN : 2287-5832(Online)
Journal of The Korean Society of Grassland and Forage Science Vol.45 No.1 pp.74-81
DOI : https://doi.org/10.5333/KGFS.2025.45.1.74

Growth Characteristics and Yields of Sorghum-Sudangrass Hybrids in Pyeongchang Region, Korea

Jeong Sung Jung1, Palaniselvam Kuppusamy1, Ilavenil Soundharrajan1, Seung Hak Yang1, Hyung Soo Park1, Jae-Hoon Woo1, Ouk Kyu Han2, Ki Choon Choi1*
1Grassland and Forages Division, National Institute of Animal Science, Cheonan 31000, Korea
2Department of Crops and Forestry, Korean National University of Agriculture and Fisheries, Jeonju 54874, Korea
* Corresponding author: Ki Choon Choi, Grassland and Forages Division, National Institute of Animal Science, Rural Development
Administration, Cheonan 31000, Korea Tel: +82‐41‐580‐6752, Fax: +82‐41‐580‐6779, E-mail: choiwh@korea.kr
March 12, 2025 March 24, 2025 March 25, 2025

Abstract


Climatic change affects agricultural, environmental and livestock production. Forage productivity is highly dependent on the weather change. The Pyeongchang region has more difficulty in cultivation of Sorghum-Sudangrass hybrids (SSH) than other warm regions because of the cold weather. This experiment was carried out to analysis the agronomic characteristics, productivity, and nutritive value of three cultivars of Sorghum-Sudangrass hybrids in the Pyeongchang region from 2021 to 2022. Two harvests were taken in each year, and the agronomic characteristics, dry matter yield, and nutrient content of the whole SSH crops were determined. The plant height ranged between 281-291 cm and 165-172 cm in the first and second harvest, respectively. Plant height of Superdan (291±49 cm) was the highest in the first cut and Dairy mens Dream (172±30 cm) was the highest in the second cut time. Stem diameter ranged from 9.5 to 8.8 mm with Superdan having a higher level than the other two cultivars. The Dairy mens Dream variety produced significantly higher dry matter yield (15,695 kg/ha) than those of Superdan (14,584 kg/ha) and Supergreen (14,300 kg/ha) over a two-year experimental period. In terms of nutritional quality, the crude protein content, neutral detergent fiber and acid detergent fiber of SSH cultivars were analysed. There were no significant changes in the content of CP, ADF and NDF ranges among the cultivars. In addition, the Superdan cultivar had slightly higher CP content (10.17%) and was followed by Dairy mens Dream (9.84%) and Supergreen (9.54%) in the second cut time of 2-year average. Dairy mens dream had lower ADF and NDF values than other cultivars; however, no significant differences amongst cultivars in fiber content were observed. Therefore, these three cultivars displayed the potential growth characteristics, DM yield and nutritive values in Pyeongchang region. Hence, the SSH cultivars have a potential to withstand the climatic change and improve SSH productivity in the study area.


Sorghum-Sudangrass hybrids , Climatic factors , Pyeongchang region , Growth characteristics , Nutrient profile

초록

    Ⅰ. INTRODUCTION

    Climatic change can influence the various fields of science including agriculture, livestock, soil, environmental and water resources (Godde et al., 2021). Particularly, the abnormal climatic events can greatly affect the crop development and production. Many agricultural activities throughout the world have been changed due to the high temperature and precipitation (Fan et al., 2022). In Korea, elevating spring/winter temperatures and high summer rainfall are considered major impacts of climatic changes. Also, the amount of rainfall in the Korean monsoon season is around 45-60% of total average annual rainfall (Fischedick et al., 2014;Kim, 2023). The livestock industry accounts for nearly half of the total value of Korea's agricultural production. With the development of the Korean livestock industries, the forage production has attracted more attention from researchers and industrialists. In Korea, the commercial animal feed manufacture and resources are relatively limited, therefore, some feed wants to be imported from overseas. To stabilize the agricultural production and livestock industry, the high-quality forage cultivation is essential in the Korean Peninsula that could reduce the feed costs and have an import replacement effect (KOSIS, 2017). Many research was carried out on forage production including sorghum, corn, alfalfa, sudan grass, and sorghum-sudangrass hybrids during 1970s in the USA, New Zealand, Japan, China, and Korea, but there are few recent studies on the production improvement. Forage Sorghum-Sudangrass hybrids [(SSH; S.bicolor (L.) Moench × S.Sudanese (Piper.) Stapf.)] are mainly grazed and can be made into silage for livestock animals (Newman et al., 2013). SSH is suitable for making silage for livestock to improve the digestibility and sustainably raise its economic value.

    Forage crops such as Corn, Sorghum, and Sorghum-Sudangrass hybrids cultivation have been conducted in humid, subtropical regions including the Southern USA, China, Japan and the Korean Peninsula (Lee et al., 2021). Sorghum-Sudangrass hybrids are economically viable crops that mainly cultivating in arid and semiarid areas (Tutar, 2024). SSH can grow and develop in harsh environment conditions including irregular rainfall and high temperature. SSH suitable temperature is to grow 22-33℃ (Peng et al., 2020). The productivity of SSH is highly depending by the various agro-climatic factors. However, the SSH crop has been showing high resistance to drought and cold environment compared with other crops (Slanev and Enchev, 2014). SSH crop characterized by relatively smaller leaf area, waxier leaf surface, more secondary roots, small diameter stems and rapid re-growth potential which may help them withstand in low rainfall and high temperatures. Also, it produces the highest dry matter yield among various forages such as maize, alfalfa, and cereal crops (Wei et al., 2021). In Korea, the different SSH varieties were cultivating for silage by livestock farmers, that preferred mainly headless types to heading types (Lee et al., 2000;Choi et al., 2017). SSH yield was slightly lower than the maize when harvested for silage, but it has the advantage that it can be cut 2-3 times during the milky maturity stage. SSH can be used as either wrapped bale silage or chopped silage and green mass, but it is best suited for grazing and hay production (Khalaf et al., 2019). SSH plant contains high portion of crude protein and moderate ranges of fibers such as lignin and semi-cellulose biomass. These nutrient compositions are major impacts on the quality of feed to livestock animals (Enchev et al., 2021). Previously, many studies have reported the SSH production under different environmental conditions and locations that effect the growth and yield properties. In this study, we investigated the growth characteristics, nutrient content and yield properties of three SSH cultivars in the Pyeongchang region from 2021 to 2022.

    Ⅱ. MATERIALS AND METHODS

    1. Study area and plot design

    The experiment was conducted in the field trial at the Pyeongchang region, Gangwon-do Province, during April 2021-September 2022. The experimental station is located at Latitude 37°26’ N and Longitude 128.39’ E. The Pyeongchang region is a warm summer, humid continental climatic zone that is located northern part of the Korean Peninsula. The average temperature is 20-25℃ and the average annual precipitation is 1000-1500 mm. The experiment was conducted via randomized block design with three replicates over two years. The plot size was 16 m2, and the row spacing was 70 cm and each plot had 4 rows. Three Sorghum-Sudangrass hybrid varieties (Dairy mens Dream, Superdan and Supergreen) were evaluated in the Pyeongchang area. The experimental site has a suitable environment for agriculture production and monthly average temperature, lowest average temperature, average precipitation and accumulated temperature information are given in Table 1. Total precipitation was received during the plant growth and maturity period (April to September) around 778, 1155 mm in 2021 and 2022, respectively (Table 2). The highest average temperatures were 26℃ and 25℃ recorded in July and August 2021, respectively, and the lowest average temperature are 2- 4℃ in the month of April 2021 and 2022. The temperature is gradually elevating up to 20-26℃ in the hot summer period. SSH plants were harvested twice in each year, and the first harvest date was August 3, and the second harvest date was September 29 of each year prepared in the experiment location.

    2. Agronomic characteristics of SSH cultivars

    SSH growth characteristics were measured using randomly selected plants from every plot on the day of cutting. The plant height and stem diameter were measured using a Vernier caliper scale. Next, the dry matter yield was determined for each individual sample by air drying 50 g samples in a hot oven at 65℃ for 72 h, then weighing the dry residual and dividing by fresh corresponding samples.

    3. Nutrient values of SSH cultivars

    The nutrient content of SSH cultivars was analysed from each group by all duplicate repetitions of the samples. Approximately 250 g samples were measured and dried at 65℃ in an air-forced drying oven for 72 h. Then, the samples were ground to pass a 1mm sieve, and the fine powdered samples were used for basic nutritional composition analysis in the Functional Central Laboratory, Grassland and Forage Division, NIAS, Cheonan, Korea. Crude protein (CP) content was measured by the classical Kjeldahl method (AOAC, 1990) using an automatic elemental analyser (Euro Vector EA3000, Italy). Acid detergent fiber (ADF) and neutral detergent fiber (NDF) were analysed using automatic fiber analyser (Ankom Technologies, USA) by Van Soest method (1991).

    4. Statistical analysis

    The statistical data were analyzed using the procedure of SPSS 24.0 (IBM Corp., NY, USA). Analysis of means value was determined using least significant difference (LSD) and Duncan multiple range test in the SPSS statistical program. P value less than 0.05 is considered statistically significant.

    Ⅲ. RESULTS

    1. Effect of climatic factors in Pyeongchang region for SSH cultivars

    The agro-meteorological factors such as temperature and precipitation faintly influenced the vegetation and productivity of Sorghum-Sudangrass cultivation in 2021 and 2022 (Table 1 and 2). During the experimental period 2021-2022, the climatic factors such as temperature and rainfall were slightly different in the Pyeongchang region, although it looks favorable for the SSH growth phase. In 2021, the summer was recorded high temperatures of 26.3 and 25.4 in July and August. Also, the average precipitation was significantly lower than the normal rainfall in the Gangwon-do region. In 2011, the average temperature and lowest average temperature for sowing to first harvest and first to second harvest were recorded at 18.0 and 12.6℃ respectively. There were no significant changes in the temperature during the same period in 2022 (Table 3). However, the rainfall was significantly lower (1-fold) from sowing to first harvest and first harvest to second harvest in 2021 compared to 2022. In May, the average temperature was gradually increased above 17℃ and 14℃ in 2021 and 2022, respectively, which leds to enhancing the germination and relatively improving the yield of SSH cultivars. The accumulated temperature was higher in September 2022 (3323.41℃) than in September 2021 (2231.35℃). Particularly, the amount of precipitation and temperature are a key factors in the production of fresh and dry matter yield of forage. In 2022, the heavy rainfall was recorded in June and August for 236.0 mm and 512.0 mm, respectively, which are requirements for SSH growth and productivity. However, the normal monthly rainfall was 100-200 mm in 2022. The lowest rainfall was reported in April (48.5 mm) and May (8.0 mm) month for the year. In 2021, the correctly spread and moderate rainfall throughout the experiment (April-September) created optimum conditions for the SSH production in the Pyeongchnag region presented in Table 2. In addition, the difference between two-year average of temperature looks not significant, and it is more favorable to bring normal growth and development of SSH crops.

    2. Growth characteristics and productivity of SSH cultivars in Pyeongchang region

    The SSH plant heights were slightly varied among cultivars in the Pyeongchang location. In this evaluation, the plant height was varied between 150 to 316 cm and does not affected by the climatic factors in the Pyeongchang region. Plant height, stem diameter, and DM yield of Sorghum- Sudangrass hybrids are shown in Table 4. In 2022, the plant height of Superdan cultivars showed the tallest (334, 150 cm), followed by Supergreen (320, 135 cm) and Dairy mens Dream (316, 126 cm) at first and second harvests, respectively. The Superdan cultivars showed slightly higher in plant height, but there was no significant difference between cultivars. In 2022, the stem diameter was appeared larger in all cultivars (8.6-9.5 mm) compared with the year 2021. Particularly, the Dairy mens Dream exhibited the least stem diameter (8.6, 8.3 mm) and the larger diameter was measured in Superdan (9.5, 8.8 mm) and Supergreen (8.8, 9.3 mm) in first and second harvest of two-year average values. Table 4 shows the total dry matter yields of the first and second harvests of SSH cultivars in 2021 and 2022. In the first cut, all cultivars are shown to be more productive and ranged between 9.1 to 9.9 MT per ha. The cultivar Dairy mens Dream produced highest dry matter yield of 15,695 kg/ha, followed by the Superdan was 14,584 kg/ha and Supergreen cultivars at 14,300 kg/ha for a two-year average. The average annual forage yield was 12-13 t/ha and 15-18 t/ha in 2021 and 2022, respectively. The SSH cultivars had lower DM yield in the second harvest of both years ranged between 4.4 to 5.7 MT/ha. The Supergreen cultivars (4,490 kg/ha) was slightly lower than those of Superdan (5,400 kg/ha) and Dairy mens Dream (5,777 kg/ha). Overall, the SSH dry matter yield was higher in 2022 than in 2021.

    3. Nutritional profile of SSH cultivars in Pyeongchang region

    The chemical ingredients in fodder may determine their quality to use as an animal feed. The SSH forage nutrient content such as CP, NDF, and ADF was quantified and data were presented in Table 5. The SSH cultivars demonstrated good CP content around 7-10% of the two-year average. Similar results for the CP values in SSH hybrids were published previously by Slanev and Enchev (2014). CP content was similar among three cultivars; however, significant differences were found between cultivation years and first and second cutting times. In 2022, the CP content was more than 9% in the second harvest time, but slightly lower in the second harvest time of all cultivars in 2021. Therefore, the cutting time and climatic factors may play a key role in the CP content. Generally, the Superdan cultivar showed a little high in CP content ranges (6.97% and 10.17%) at first and second harvests, respectively, followed by Dairy mens Dram and Supergreen was found to be 6-9%, as averaged two years in both harvest times. Also, the NDF content was slightly higher in Superdan cultivars ranged between 65.54% and 61.94%, as two year averaged data of first and second cut time respectively. Dairy mens Dream had the lowest NDF values, including 62.92% in the first cut and 61.31% in the second cut time of the combined two years. In 2022, the ADF values were determined in all cultivars ranging between 30-40%. However, the ADF range was higher in the first cutting time than in the second cutting time of all cultivars. The ADF fiber content was lowest in Dairy mens Dream (38.77 and 33.57%), followed by Supergreen (40.62 and 32.24%) and Superdan (41.50 and 33.83%) in the first and second cuts, respectively.

    Ⅳ. DISCUSSION

    The thermal variation and uneven rainfall can affect the crop growth, yield, and nutrient profile. The summer-concentrated precipitation in the central area of the Korean Peninsula exceeded the suitable range of SSH requirements that leads to reducing the growth and yield rate. In 2021, the average temperature was slightly increased in July and August, whereas, at the same time, the average rainfall was lower than 100 mm. In 2022, the accumulated temperature was highest, which is beneficial for SSH growth, but the rainfall sums for April (48.5 mm) and May (8.0 mm) were lower than the average for those months in the previous year. Recently, Kim and Sung (2023) reported that the different weather events that look like did not affect the forage production in the Northern and central areas of the Korean peninsula, even with the increasing hot temperatures and intensity of heavy rainfall. In addition, the climatic trend may be favorable for the SSH production.

    Several studies suggested that the plant height was considered a good indicator of crop performance for feed production (Yartsev et al., 2024). The structural elements of the SSH forages may differ significantly based on the cultivars, location, and climatic factors. In this study, we noticed that the plant height was differed in the first and second harvest times. Among hybrid varieties, the plant height and stem diameter were slightly varied between cultivars and years too. On average, in two years of study, the Superdan cultivars was significantly taller (291±49 cm) in comparison to Supergreen (286±40 cm) and Dairy mens Dream (281±43 cm). Thus, the height of SSH cultivars was lower in the second harvest of both year 2021 and 2022. The plant height of Supergreen was least in the second harvest followed by Superdan and Dairy mens Dream cultivars. The stem diameter of Superdan was slightly higher in both harvests than all other cultivars; however, the smallest stem diameter was measured in Dairy mens Dream cultivars (86±1.2, 86±1.1 mm) in the first and second harvests, respectively. Similarly, Kushkhov et al. (2021) reported the plant heights were significantly lower in the second harvest, ranged from 95-185 cm in the SSH population, with the highest being in the first harvest of the same SSH population (174-284 cm). Millner et al. (2011) also published the significant difference in the plant height at the time of harvest yield measurement, including the Sugargraze (153.9 cm) which had a highest height than all other cultivars, Pac BMR (89.1), followed by Nutrifeed (76.9 cm) measured. The average plant height is 118-120 cm were measured in KH12SU9001 and KH12SU9002 varieties, but the crop height has no significant difference between hybrids because the biochemical and physiological behavior of plants may be similar, and it could be changed when the plant grown in different soil nutrient and climatic conditions (Khalaf et al., 2019). In this study, we found that the SSH cultivars had a higher dry matter yield in the first cut than in the second cut time. We also observed the slight variation between cultivars in DM yield at the Pyeongchang location, and the reports strongly support our study previously published. However, the location and cultivar differences were found significant only for dry matter yield and other agronomic profile did not shows much change among cultivars and years (Kuppusamy et al., 2024). Similarly, Ali et al. (2014) suggested the Superdan cultivars produced significantly higher fresh forage yield in different location. In addition, the Jimah region had significantly higher yield as compared to the other locations. Recently, Yartsev et al. (2024) reported the Sorghum-sudangrass produced a lower yield 10.66 t/ha, which is lower than the sweet sorghum and Sudangrass forages cultivated in the same location and condition in 2022. Though, the average value of dry mass yield was 22 t ha-1 for SSH cultivars reported earlier by Slanev and Enchev (2014). Therefore, the selected three SSH cultivars in the Pyeongchang region could be potential for the cultivation, DM yield and profitability for the livestock feed industry.

    Weather patterns and cultivars can impact the quality yield and nutrient profile of the forages. Also, the crude protein and fiber content ranges are directly related to factors like the cultivar cycle, harvest time, night temperature, rainfall amount and others (Sowinski et al., 2011;Jung et al., 2019). In this work, the SSH nutrient profile was measured over two cuts of each year grown in the Pyeongchang location. Previously, we also reported the productivity and growth characteristics of the same SSH cultivars in different locations including Cheonan and Jeju Island. The SSH productivity have noticed significant variance due to the location and climatic factors. Though, the SSH cultivars were not significant in nutrient level. In 2022, the CP percentages were slightly higher in both cutting time than in 2021. The mean CP content of SSH cultivars (9-10%) was nearly similar to the CP content (12-14%) for SSH cultivation in New Zealand reported by Millner et al. (2011). Also, the fiber content (ADF and NDF) are the main indications of the energy capacity of green forage. The ADF content in selected SSH cultivars showed greater than 30% in the first and second harvest periods. The high NDF level in forage might decrease the fodder consumption by animals (Seo et al., 1999;Uzun et al., 2009). In our study, the SSH cultivars showed 58-62% of NDF values in 2022, but it was slightly higher than in 2021, although the acceptable NDF content limit is 50-60%. Similarly, Lima et al. (2017) reported the NDF content of SSH cultivars ranged from 58.52 to 61.27%; some of the genotypes showed high values of the fiber content. The average summer ADF is 350 g/kg, and the NDF ranges from 510 g/kg in the Sorghum-Sudangrass variety. In addition, the autumn SSH forage cultivation has increased fiber content compared to the summer SSH cultivation crop. The results of nutritive values by SSH according to each harvest times showed no difference in nutritive values. However, nutritive values by SSH of the first harvest showed a difference from nutritive values of the second harvest. This suggest that the difference in nutritive values is due to the fact that plants regenerate and grow for a certain period of time after they are harvested.

    Ⅴ. CONCLUSIONS

    In conclusion, the study revealed the SSH cultivars Dairy mens Dream, Superdan and Supergreen were virtuous growth profile and productivity in the Pyeongchang region, Korea. Crop height and dry matter yield of SSH cultivars were slightly varied among cultivars, but there were no significant differences between three cultivars in Pyeongchang region. In addition, the SSH plant height and DM yield were greater in 2022 than in 2021 likely due to the high amount of precipitation received in 2022. The CP content showed a difference only in terms of first and second cutting time, but there was no significant difference among the SSH varieties. Also, the NDF and ADF amount changes differently only between the years and harvest time. The cultivation of SSH could be useful to meet the quality forage production for livestock and domestic animals and needs to be increased. Furthermore, our study confirms that the Pyeongchang location is more favorable in terms of better climatic conditions to cultivate and develop these SSH cultivars. However, the trial should be conducted at least three years for the results to be more reliable.

    Ⅵ. ACKNOWLEDGMENTS

    The research project was supported by the National Institute of Animal Science, Rural Development Administration, Republic of Korea, Project titled “Damage assessment of forages and development of cultivation technology for their damage reduction according to extreme weather (PJ01499601)”.

    Figure

    Table

    Monthly average temperature and the lowest average temperature during cultivation periods of Sorghum-Sudangrass hybrids in Pyeongchang region

    Monthly average precipitation and accumulated temperature during cultivation periods of Sorghum-Sudangrass hybrids in Pyeongchang region

    Monthly average temperature, the lowest average temperature and average precipitation by harvest time of Sorghum-Sudangrass hybrids in Pyeongchang region

    Growth characteristics and DM yields of Sorghum-Sudangrass hybrids in Pyeongchang region

    Same Capital alphabets within a column indicates significant differences among three years (p<0.05).

    Nutritive values of Sorghum-Sudangrass hybrids in Pyeongchang region

    *Mean±SE, CP: Crude protein; ADF: Acid detergent fiber; NDF: Neutral detergent fiber

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