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ISSN : 2287-5824(Print)
ISSN : 2287-5832(Online)
Journal of The Korean Society of Grassland and Forage Science Vol.46 No.3 pp.220-229
DOI : https://doi.org/10.5333/KGFS.2026.46.3.220

Growth, Productivity, and Forage Quality Responses of Summer Forage Crops to Drought and Waterlogging Stress

Seung Min Jeong, Jin Woo Jeong, Seung Hak Yang, Jae Hoon Woo, Ha Neul Ko*
Forages Production Systems Division, National Institute of Animal Science, Cheonan 31000, Republic of Korea
*Corresponding author: Ha Neul Ko, Forages Production Systems Division, National Institute of Animal Science, Cheonan 31000, Republic of Korea. Tel: +82-41-580-6771, Fax: +82-41-580-6779, E-mail: neul24@korea.kr
September 21, 2026 September 27, 2026 September 27, 2026

Abstract


Drought and waterlogging threaten forage production in Korea. This study evaluated growth, dry matter (DM) yield, relative DM yield, and forage composition of five summer forage entries in separate drought and waterlogging experiments. Late- and early-maturing barnyard millet, bermudagrass, teff grass, and a sorghum-sudangrass hybrid were assigned to control, 10-d stress, and 19-d stress treatments with three replicate plots per treatment. Bermudagrass and teff grass failed to survive in the waterlogging experimental area, including the control plots, preventing quantitative treatment comparisons for these entries. Under drought, no significant DM-yield differences were detected in late-maturing barnyard millet, whereas teff DM yield decreased significantly from 5,172 kg ha−1 in the control to 4,224 and 2,932 kg ha−1 after 10 and 19 d, respectively. Relative DM yields after 19 d of drought were 94.5, 81.3, 72.2, 64.4, and 56.7% for late-maturing barnyard millet, the sorghum-sudangrass hybrid, bermudagrass, early-maturing barnyard millet, and teff grass, respectively. Under waterlogging, DM yield differed significantly among the control, 10-d, and 19-d treatments within each of the three entries with quantitative data. Their relative DM yields after 19 d were 64.4, 54.3, and 15.2% for late-maturing barnyard millet, early-maturing barnyard millet, and the sorghum-sudangrass hybrid, respectively. Forage-composition patterns varied among entries and did not consistently parallel DM-yield responses. These findings support evaluating responses to drought and waterlogging separately when screening forage entries. Descriptive yield rankings require validation across years, locations, and additional cultivars.


Barnyard millet , Climate resilience , Drought , Forage quality , Sorghum-sudangrass hybrid , Waterlogging

초록

    Ⅰ. INTRODUCTION

    Stable production of high-quality domestic forage is essential for reducing feed-cost exposure and supporting sustainable ruminant production in Korea. At the same time, forage cultivation is increasingly affected by climate variability because biomass production depends strongly on seasonal temperature and water availability. Recent Korean studies have linked forage productivity to precipitation as well as temperature. Recent annual precipitation was lower than the 2006–2015 baseline, and severe spring drought in southern Korea was associated with a 9.4% reduction in Italian ryegrass (IRG) dry matter yield (Yang et al., 2025). Precipitation and thermal variables have also been identified as important climate-exposure indicators for IRG productivity (Yoon et al., 2025). These findings are consistent with broader evidence that changes in water availability are among the principal pathways through which climate change affects crop yields (Rezaei et al., 2023).

    Both water deficit and excess water are relevant to Korean forage systems. Drought suppresses cell expansion, photosynthesis, and biomass accumulation, but the magnitude of damage can differ among species and genotypes. In Korea, Cultivar-dependent drought responses have been reported in IRG (Yoon et al., 2024), while the productivity of sorghum-sudangrass hybrids has been shown to vary among years with contrasting weather conditions (Kuppusamy et al., 2024). Conversely, prolonged soil saturation restricts oxygen diffusion into roots and can reduce growth and nutrient acquisition. Kim et al. (2024) showed that waterlogged IRG altered adventitious-root development, root porosity, carbohydrate metabolism, and alcohol dehydrogenase activity, indicating that tolerance to excessive soil water requires distinct morphological and metabolic responses.

    Stress responses should therefore be evaluated on a crop-specific basis and should include forage nutritive value as well as biomass. Recent studies reported substantial genotypic variation in drought responses of bermudagrass, teff, forage sorghum, and pearl millet (Noor et al., 2024;Alemu et al., 2024;Ajoudani et al., 2024;Parray et al., 2025). Waterlogging can likewise reduce yield more strongly than quality and its effects depend on species, stress duration, and environmental conditions (Yang et al., 2024). Although Korean studies have increasingly addressed climate sensitivity of individual forage species, direct comparisons of several summer forage crops under standardized drought and waterlogging remain limited.

    Accordingly, this study compared major summer forage crops under contrasting soil-water conditions to evaluate crop-specific changes in plant growth, DM production, relative DM yield, and forage quality under drought and waterlogging stress. The results provide baseline information for identifying forage crops with relatively stable productivity under abnormal soil-water conditions and for selecting climate-resilient summer forage crops in Korea.

    Ⅱ. MATERIALS AND METHODS

    1. Experimental site and plant materials

    The experiment was conducted at the experimental field of the National Institute of Animal Science (NIAS), Rural Development Administration, Cheonan 31000, Republic of Korea. Five warm-season forage entries were used: late-maturing barnyard millet (Echinochloa spp.), early-maturing barnyard millet (Echinochloa spp. cv. Shirohie), bermudagrass [Cynodon dactylon (L.) Pers., Ecotype], teff grass [Eragrostis tef (Zucc.) Trotter cv. Boise], and a sorghum-sudangrass hybrid [Sorghum bicolor (L.) Moench × Sorghum sudanense (Piper) Stapf cv. Dairy Mens Dream]. All forage entries were sown on June 7 2024 by drill seeding. The seeding rates were 20 kg ha−1 for both barnyard millet entries and bermudagrass, 7 kg ha−1 for teff grass, and 30 kg ha−1 for the sorghum-sudangrass hybrid. Barnyard millet, bermudagrass, and teff grass were sown in four rows at a row spacing of 25 cm, whereas the sorghum-sudangrass hybrid was sown in two rows at a row spacing of 50 cm. Each experimental plot had an area of 2 m2. Drought and waterlogging were evaluated as two independent experiments. Within each experiment, each forage entry was subjected to three treatments consisting of a control, a 10-d stress treatment, and a 19-d stress treatment, with three independent replicate plots per treatment. Accordingly, nine plots were assigned to each forage entry within each water-stress experiment, resulting in 18 plots per forage entry across the drought and waterlogging experiments and a total of 90 experimental plots for the five forage entries. The experiment was arranged according to a randomized complete block design (RCBD). The drought and waterlogging experiments were established in spatially separate sections within a rainout-shelter facility. Natural precipitation was therefore excluded from the experimental plots during the treatment period. Physical barriers were installed in the soil between the experimental sections and adjacent plots to minimize lateral movement of water through the soil. The barriers were installed to a depth of approximately 1 m. The distance between adjacent plots or experimental sections was approximately 1 m. Fertilizer was applied at rates of 80 kg N ha−1, 200 kg P2O5 ha−1, and 70 kg K2O ha−1.

    2. Drought and waterlogging treatments and soil moisture monitoring

    Drought and waterlogging were conducted as two independent water-stress experiments. In each experiment, three water-regime treatments were established for each forage entry: a control, a 10-d stress treatment, and a 19-d stress treatment. Each treatment consisted of three independent replicate plots (n = 3). The 10- and 19-d treatments were assigned to separate experimental plots; therefore, plots harvested after 10 d were not subsequently sampled at 19 d, and the observations obtained at the two treatment durations represented independent experimental units rather than repeated measurements of the same plants. All forage entries were sown on June 7 2024, and the drought and waterlogging treatments were initiated simultaneously on July 23 2024. Thus, water-stress treatments were imposed on the same calendar date for all forage entries rather than being initiated at a common developmental stage. Because the tested entries differed in maturity and growth characteristics, their developmental stages at the initiation of stress were not necessarily identical. The 10- and 19-d treatments were harvested as follows: Barnyard millet - Heading stage; Bermudagrass - 30~40 cm of plant height; Teff grass - Early boot stage; Sorghum-sudangrass hybrid - Early heading stage Both experiments were conducted under a rainout shelter to exclude natural precipitation during the stress-treatment period. In addition, physical barriers installed in the soil were used to restrict lateral movement of water between the drought and waterlogging experimental areas and among plots. This arrangement allowed the contrasting soil-water conditions of the two experiments to be maintained independently.

    In the drought experiment, irrigation to the 10- and 19-d stress plots was withheld beginning on July 23, while the drought-control plots were irrigated according to twice daily for 15 min. Because natural rainfall was excluded by the rainout shelter, changes in soil moisture during the drought treatment primarily reflected the imposed irrigation regime rather than rainfall during the experimental period. In the waterlogging experiment, water was supplied to the 10- and 19-d treatment plots to maintain a depth of 5 cm throughout the respective treatment periods. The water condition was checked daily and maintained by water-supply method. The control plots within the waterlogging experimental area were not subjected to the additional waterlogging treatment but were maintained according to the baseline water-management condition of that experimental area.

    Soil-moisture measurements confirmed that the baseline soil-moisture condition of the waterlogging experimental area was higher than that of the drought experimental area. In the waterlogging experiment, final and mean soil-moisture contents of the control were 31.9 and approximately 33.5%, respectively, compared with 39.7 and approximately 42.4% after 10 d of waterlogging and 43.5 and approximately 41.1% after 19 d of waterlogging. In the drought experiment, final soil moisture decreased from 25.2% in the control to 19.0 and 15.0% after 10 and 19 d of drought, respectively. Bermudagrass and teff grass failed to survive in the waterlogging experimental area, including the control plots. Because bermudagrass and teff did not survive in the waterlogging experimental area, including the control plots, quantitative data on plant height, DM yield, SPAD values, and forage composition were unavailable for these entries. Consequently, their responses to the additional waterlogging treatments could not be estimated.

    Soil moisture was monitored throughout the treatment period using wireless automated soil-moisture sensors ([Groundwater level sensors DT-WLS01], [Damoatech], [Seongnam-si], [Korea]). Sensors were installed at a soil depth of 20 cm, with 6 sensors installed each drought and waterlogging plots, and soil-moisture values were recorded at 30 min intervals. Both the soil-moisture value at the end of each treatment and the mean value recorded over the treatment period were used to characterize the realized soil-water conditions.

    3. Growth characteristics and forage yield

    Growth characteristics and forage productivity were evaluated for each crop under the control and water-stress treatments. Plant height and SPAD chlorophyll index were measured immediately before harvest. Plant height was determined from the soil surface to the uppermost part of the plant, and chlorophyll status was evaluated using a SPAD chlorophyll meter (Minolta, Japan). Forage biomass was harvested separately from each experimental unit. Fresh forage weight was recorded, and representative subsamples were collected to determine dry matter (DM) concentration. The subsamples were dried in a forced-air drying oven until a constant weight was obtained, and DM yield was calculated from fresh forage yield and DM concentration. Dry matter yield was subsequently converted to kg ha−1. To compare yield stability among crops differing in potential productivity, relative DM yield was calculated separately for each stress treatment using the following equation: Relative DM yield (%) = ( DM yield under stress DM yield of the corresponding control ) × 100 . This index was used as a descriptive measure of the capacity of each forage crop to maintain biomass production under drought or waterlogging conditions.

    4. Forage quality analysis

    Dried forage samples were ground prior to chemical analysis. Crude protein (CP) concentration was determined according to the procedures of the Association of Official Analytical Chemists (AOAC, 1990). Neutral detergent fiber (NDF) and acid detergent fiber (ADF) concentrations were determined according to the detergent fiber procedures of Van Soest et al. (1991). Total digestible nutrients (TDN) were estimated from ADF concentration using the equation commonly applied for forage evaluation: TDN ( % ) = 88.9 − ( 0.79 × ADF , % ) , as described by Holland et al. (1990). CP, NDF, ADF, and TDN concentrations were expressed on a DM basis.

    5. Statistical analysis

    Each treatment was represented by three independent replicates (n = 3). Because different experimental units were harvested at each sampling time, observations obtained from the control, 10-day, and 19-day treatments were considered independent. Statistical analyses were conducted separately for each forage crop within the drought and waterlogging experiments. Treatment effects on plant height, dry matter (DM) yield, SPAD value, and forage-quality characteristics were analyzed by one-way analysis of variance using the ANOVA procedure (PROC ANOVA) of SAS software (SAS Institute Inc., Cary, NC, USA). When a significant treatment effect was detected, treatment means were separated using Tukey’s honestly significant difference (HSD) test. Differences among treatment means were considered significant at p<0.05. Data are presented as treatment means, and the standard error of the mean (SEM) is provided in the tables. Relative DM yield was calculated from the corresponding treatment and control DM yields and was used as a descriptive yield-maintenance index; therefore, statistical letters assigned to the original DM yield data were not interpreted as direct statistical comparisons among relative DM yield values of different forage crops.

    Ⅲ. RESULTS AND DISCUSSION

    1. Soil moisture conditions under drought and waterlogging

    The treatments produced contrasting soil-moisture conditions (Table 1). In the drought experiment, final soil moisture was 25.2% in the control and 19.0 and 15.0% in the 10- and 19-d treatments, respectively; the corresponding mean values were 24.2, 20.1, and 17.6%. In the waterlogging experiment, final soil moisture was 31.9% in the control and 39.7 and 43.5% in the 10- and 19-d treatments, respectively. Mean soil moisture was 33.5, 42.4, and 41.1%, respectively, indicating higher mean moisture in both waterlogging treatments than in the control, but not a monotonic increase with treatment duration. These values describe the realized treatment environments and were not subjected to statistical comparison.

    2. Growth and dry matter productivity under drought

    Drought responses differed markedly among the forage entries (Table 2). Late-maturing barnyard millet maintained DM yield at 97.1 and 94.5% of the control after 10 and 19 d of drought, respectively, and plant height, DM yield, and SPAD did not differ significantly among treatments. In contrast, early-maturing barnyard millet showed significant reductions in plant height and DM yield after 19 d, when relative DM yield declined to 64.4%, and SPAD (Soil Plant Analysis Development meter) was lower at both stress durations. This contrast should be interpreted as a difference between the specific entries tested rather than as a maturity-group effect because maturity and genotype were not independently separated in the experimental design. Comparable within-species variation has been reported in Korean IRG studies, in which cultivars grown under the same conditions differed in drought response and forage performance (Yoon et al., 2024;Min et al., 2024). Variation in productivity and nutritive characteristics among barnyard millet genetic materials has also been demonstrated in the recently developed cultivar 'Da-on' (Choi et al., 2025).

    The sorghum-sudangrass hybrid retained 96.4 and 81.3% of control DM yield after 10 and 19 d of drought, respectively. DM yield and SPAD were significantly lower in the 19-d treatment than in both the control and the 10-d treatment, whereas plant height did not differ significantly among treatments. Ajoudani et al. (2024) also reported reduced forage sorghum biomass under restricted water availability. In bermudagrass, DM yield was significantly lower after both 10 and 19 d of drought than in the control, but the two drought treatments did not differ significantly. Relative DM yields were 76.8 and 72.2%, respectively. Plant height did not differ significantly among treatments, whereas SPAD was significantly lower after 19 d than in the control and the 10-d treatment. These results show that a lack of a detectable height response does not necessarily indicate maintenance of forage biomass.

    In teff grass, DM yield decreased from 5,172 kg ha−1 in the control to 4,224 and 2,932 kg ha−1 after 10 and 19 d of drought, respectively, with significant differences among all three treatment means (p<0.05). Relative DM yields were 81.7 and 56.7%, corresponding to reductions of 18.3 and 43.3% relative to the control. Plant height was significantly lower after 19 d than in the control and the 10-d treatment, whereas the latter two treatments did not differ significantly. Thus, a significant DM-yield reduction was already detected in the 10-d treatment, before a significant difference in plant height was detected. Alemu et al. (2024) also reported reduced shoot and total dry weight under water deficit, together with variation in physiological drought responses among tef genotypes. The present results apply to the tested teff entry and do not establish a species-wide ranking of drought tolerance.

    3. Growth and dry matter productivity under waterlogging

    Waterlogging reduced DM yield in all three forage entries for which quantitative data were available (Table 3). In late-maturing barnyard millet, DM yield decreased from 14,338 kg ha−1 in the control to 12,525 and 9,231 kg ha−1 after 10 and 19 d of waterlogging, respectively, with significant differences among all three means (p<0.05). Relative DM yields were 87.4 and 64.4%. Plant height was significantly lower in both waterlogging treatments than in the control, but the 10- and 19-d treatments did not differ significantly. In early-maturing barnyard millet, DM yield decreased from 12,582 kg ha−1 in the control to 9,961 and 6,829 kg ha−1 after 10 and 19 d, respectively; all three treatment means differed significantly (p<0.05). Relative DM yields were 79.2 and 54.3%, corresponding to reductions of 20.8 and 45.7%. The corresponding plant heights were 160.8, 162.2, and 149.3 cm. SPAD did not differ significantly among treatments in either barnyard millet entry.

    Among the three forage entries with quantitative waterlogging data, the sorghum-sudangrass hybrid showed the largest numerical reduction in relative DM yield. Its DM yield decreased from 10,732 kg ha−1 in the control to 3,625 and 1,634 kg ha−1 after 10 and 19 d, respectively, and all three means differed significantly (p<0.05). Relative DM yields were 33.8 and 15.2%. Plant height was 257.3, 180.1, and 122.8 cm in the control, 10-d, and 19-d treatments, respectively, whereas SPAD did not differ significantly among treatments. Waterlogging restricts oxygen diffusion in the root zone, thereby limiting aerobic respiration, nutrient acquisition, and shoot growth. Kim et al. (2024) demonstrated that waterlogged IRG responds through adventitious-root development, increased root porosity, and metabolic adjustment, while Zhang et al. (2025) showed that waterlogging-tolerant sorghum genotypes maintained growth through stronger adventitious-root and aerenchyma development and enhanced anaerobic respiratory activity. Although these mechanisms were not measured in the present study, the severe production loss of the tested sorghum-sudangrass hybrid indicates that comparatively favorable drought performance should not be assumed to confer tolerance to waterlogging.

    After 19 d of waterlogging, relative DM yield was 64.4% in late-maturing barnyard millet, 54.3% in early-maturing barnyard millet, and 15.2% in the sorghum-sudangrass hybrid. Thus, the crop ranking under waterlogging differed substantially from that observed under drought. Bermudagrass and teff grass failed to survive the imposed waterlogging conditions, and consequently, quantitative measurements of growth and DM production could not be obtained for these two species. Although their responses could not be included in the quantitative comparison of relative DM yield, the observed mortality indicates a high susceptibility of these entries to prolonged waterlogging under the conditions of the present experiment, and direct comparisons of waterlogging tolerance across all five entries are therefore not possible.

    4. Forage quality responses and agronomic implications

    Forage-quality responses varied among the tested entries and did not consistently parallel changes in DM yield (Tables 4 and 5). No significant treatment differences in CP, NDF, ADF, or estimated TDN were reported for late-maturing barnyard millet under either stress. In early-maturing barnyard millet, CP concentration was 6.05, 5.20, and 10.96% DM in the control, 10-d, and 19-d drought treatments, respectively. The 10-d drought treatment had significantly higher NDF and ADF concentrations and a lower estimated TDN concentration than the control and the 19-d treatment. Under waterlogging, the 10-d treatment had significantly higher CP, NDF, and ADF concentrations and a lower estimated TDN concentration than the other treatments. For these traits, values in the 19-d waterlogging treatment were closer to the control values. Because the two stress durations were assessed in independent plots, these between-treatment differences do not demonstrate recovery within the same plants. Concentration-based quality measures should therefore be interpreted together with DM yield.

    Under drought, the sorghum-sudangrass hybrid had CP concentrations of 4.82, 5.75, and 4.96% DM in the control, 10-d, and 19-d treatments, respectively (Table 4). NDF concentrations were 65.30, 63.90, and 61.30% DM, while ADF concentrations were 38.20, 37.80, and 34.90% DM. The higher CP concentration in the 10-d treatment represents a difference among independently sampled plots and does not establish a transient response within the same plants. Ajoudani et al. (2024) also reported increased CP concentration despite reduced sorghum biomass under water deficit. Thus, a higher nutrient concentration does not necessarily indicate greater total forage production. Under waterlogging, the hybrid experienced a substantial reduction in DM yield, whereas no significant treatment differences were detected in CP, NDF, ADF, or estimated TDN (Table 5). Yang et al. (2024) reported different responses of grain yield and grain quality to waterlogging; however, those grain-based results do not directly establish the response of whole-plant forage composition.

    From an agronomic perspective, the contrasting responses to drought and waterlogging support stress-specific crop selection for Korean forage systems. The late-maturing barnyard millet entry showed the highest numerical yield maintenance under drought and retained 64.4% of control DM yield under waterlogging while maintaining relatively stable forage-quality traits. The sorghum-sudangrass hybrid maintained comparatively high productivity during drought but was highly susceptible to prolonged waterlogging. These patterns are relevant to Korean production environments, where precipitation variability has been identified as an important determinant of forage productivity (Yang et al., 2025;Yoon et al., 2025) and agricultural climate-risk research emphasizes adaptation to both drought and flooding (Kim et al., 2025). However, the present field experiment included three replicates and specific crop entries under imposed stress conditions. Therefore, the numerical rankings should be validated across years, locations, soil types, and additional cultivars before broad recommendations are made. Within these limitations, relative DM-yield maintenance combined with forage-quality traits provides a practical first-stage framework for screening summer forage crops for increasingly variable soil-water regimes.

    Ⅳ. CONCLUSION

    This study showed different numerical patterns of DM-yield maintenance under drought and waterlogging. Late-maturing barnyard millet retained 94.5% of control DM yield after 19 d of drought, with no significant treatment differences detected. In teff grass, DM yield was significantly reduced after 10 d and was further reduced after 19 d. Under waterlogging, DM yield differed significantly among all three treatments within late-maturing barnyard millet, early-maturing barnyard millet, and the sorghum-sudangrass hybrid. Their relative DM yields after 19 d were 64.4, 54.3, and 15.2%, respectively. Late-maturing barnyard millet therefore retained a comparatively high numerical yield, but still experienced a significant 35.6% reduction under waterlogging. Bermudagrass and teff grass failed to survive in the waterlogging experimental area, including the controls, so the effects of the additional waterlogging treatments could not be quantified for these entries. Forage composition did not consistently parallel biomass production, supporting joint evaluation of DM yield and nutritive value. These results provide preliminary information for stress-specific screening of the tested forage entries. These descriptive rankings from one site and growing season, with three replicates per treatment, do not establish species-wide tolerance or broad cultivar recommendations. Further evaluation across years, locations, and genotypes is required.

    Ⅴ. ACKNOWLEDGEMENT

    This work was carried out with the support of “Development of alternative forage resources for grasses and forage crops in response to abnormal weather conditions (Project No. RS-2024-00398233)”, 2026 the RDA Fellowship Program of National Institute of Animal Science, Rural Development Administration, and 2026 collaborative research program between university and Rural Development Administration, Republic of Korea.

    Figure

    Table

    Soil moisture conditions under drought and waterlogging treatments
    Soil moisture values describe the imposed treatment environment. No statistical comparison was performed because replicate-level variability was not available for these environmental measurements.
    Growth and dry matter productivity of summer forage crops under drought stress
    Within each crop and variable, means followed by different superscript lowercase letters differ significantly (p<0.05); values without letters did not differ significantly. SEM, standard error of the mean; DM, dry matter. Relative DM yield (%) = stress-treatment DM yield / control DM yield × 100 and was used as a descriptive yield-maintenance index.
    Growth and dry matter productivity of summer forage crops under waterlogging stress
    Within each crop and variable, means followed by different superscript lowercase letters differ significantly (p<0.05); values without letters did not differ significantly. SPAD, Soil Plant Analysis Development; SEM, standard error of the mean; ND, no data; NA, not available; DM, dry matter. Relative DM yield (%) = stress-treatment DM yield / control DM yield × 100. Bermudagrass and teff grass failed to survive in the waterlogging experimental area, including the control plots; consequently, quantitative data were unavailable for these entries, and the effects of the additional waterlogging treatments could not be estimated.
    Forage quality of summer forage crops under drought stress
    Within each crop and variable, means followed by different superscript lowercase letters differ significantly (p<0.05); values without letters did not differ significantly. SEM, standard error of the mean; CP, crude protein; NDF, neutral detergent fiber; ADF, acid detergent fiber; TDN, total digestible nutrients.
    Forage quality of summer forage crops under waterlogging stress
    Within each crop and variable, means followed by different superscript lowercase letters differ significantly (p<0.05); values without letters did not differ significantly. SEM, standard error of the mean; ND, no data; NA, not available; CP, crude protein; NDF, neutral detergent fiber; ADF, acid detergent fiber; TDN, total digestible nutrients. Bermudagrass and teff grass failed to survive in the waterlogging experimental area, including the control plots; consequently, quantitative data were unavailable for these entries, and the effects of the additional waterlogging treatments could not be estimated.

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