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Evaluation of Growth Characteristics, Productivity, and Feed Value of Different 26 Alfalfa Cultivars in Central Region of South Korea

Yowook Song, Sang-Hoon Lee, Md Atikur Rahman, Hyung Soo Park, Jae Hoon Woo, Bo Ram Choi, Eun A Lim, Ki-Won Lee*

National Institute of Animal Science, Rural Development Administration, Cheonan-si 31000, Republic of Korea

Abstract: This study was conducted in Cheonan of central region in South Korea to identify alfalfa cultivars with superior adaptability to the local environment. To evaluate the growth characteristics, productivity, and feed value of 26 alfalfa cultivars, field experiments were conducted with a randomized block design (three replicates) for three years. Among the 26 alfalfa cultivars, “Natsuwakaba” showed the highest dry matter yield (DMY, 37,083 kg/ha), with a significantly higher three-year average than that of other cultivars. Furthermore, the three-year-average DMYs of “Alfalfa short” (31,044 kg/ha) and “Radar II Brand” (31,163 kg/ha) were significantly higher than those of other cultivars. In addition, differences among the feed values of the alfalfa cultivars were relatively less significant than the differences among their productivity, as the feed value was less influenced by the cultivation conditions and cultivars. Although “Jin Huang Hou” and “Certified organic” exhibited the highest feed values when cultivated in central region in South Korea, “Natsuwakaba” outperformed all cultivars in both productivity and feed value. The acid and neutral detergent fiber (ADF and NDF, respectively) contents of “Jin Huang Hou” (38.9% and 47.26%, respectively) were significantly lower than those of other cultivars. In contrast, the ADF and NDF contents of “Burgaltai” (46.52% and 55.56%, respectively) implied poor feed value upon cultivation in South Korea. The crude protein (CP) content in the alfalfa cultivars ranged from 14.95% to 19.44% during early flowering, and the highest CP content was observed for “Certified organic.” The in-vitro digestibility of alfalfa was approximately 70% for all cultivars during early flowering, indicating good digestibility of most of the cultivars.

Keywords: alfalfa cultivars, feed productivity, feed value

Received May 22, 2021; Revised June 28, 2021; Accepted July 08, 2021

Citation: Yowook Song, Sang-Hoon Lee, Md Atikur Rahman, Hyung Soo Park, Jae Hoon Woo, Bo Ram Choi, Eun A Lim, Ki-Won Lee, Evaluation of Growth Characteristics, Productivity, and Feed Value of Different 26 Alfalfa Cultivars in Central Region of South Korea. Journal of Food and Nutrition Research, 9 (7). 350-356. January 2021. doi:10.12691/jfnr-9-7-4

1. Introduction

Most legumes use atmospheric nitrogen fixed by symbiotic bacteria for growth and return the excess nitrogen to the soil [1,2,3]. Atmospheric nitrogen fixation, which is enhanced by a dry environment, low pH, presence of heavy metals, and poor soil nutrient content [4], is particularly advantageous in nitrogen-poor soils [5].

Alfalfa (Medicago sativa L.), also called the “Queen of grasses,” is a perennial pasture grass with high nutritional value, and it is greatly favored by livestock. The crude protein (CP) content of alfalfa harvested during the pre-flowering and full-bloom stages is 23.79% and 17.06%, respectively, and the CP content of alfalfa stems and leaves is similar [6]. Although alfalfa is a deep-rooted crop with a high feed value, it cannot grow under dry conditions. However, the deep roots of alfalfa accumulate more nitrogen than any other legume and can fix 40–80% of atmospheric nitrogen through nitrogen fixation [7]. According to [8], the dry weight of alfalfa roots cultivated under four-year manure treatment is 1,141-1,475 kg/ha, indicating the high growth rate of alfalfa roots, which are not substantially damaged by dry soil conditions. However, wet summers in South Korea are not favorable for alfalfa cultivation. Therefore, most of the alfalfa is imported to South Korea from other countries, where it is cultivated primarily for foraging, hay, and pellet processing. Previous studies have investigated the cultivation of members of the families Poaceae, such as orchard grass, Italian ryegrass, rye, and oat [9,10,11,12], and Fabaceae, with a focus on paddy field crops in South Korea [13,14,15]. Thus, further investigations on alfalfa cultivation in South Korea are necessary to reduce the cost of livestock production. Therefore, this study aimed to identify alfalfa cultivars suitable for cultivation in South Korea by evaluating the growth characteristics, productivity, and feed value of 26 alfalfa cultivars in Cheonan-si, South Korea.

2. Materials and Methods

2.1. Experimental Site

The seeds of 26 alfalfa cultivars were sown at an experimental site (36° 56′ 05.8″ N, 127° 06′ 11.4″ E) in the National Institute of Animal Science, Seobuk-gu, Cheonan-si, Chungcheongnam-do, on September 10, 2016 and cultivated until the fall of 2019. The average monthly temperature and precipitation at the experimental site during the study period are shown in Figure 1.

Figure 1. Climatic conditions of the experimental site during 2007–2018 and the experimental period

The alfalfa cultivars used in this study included 10 cultivars imported from Canada (“Hybiriforce-2410,” “4030,” “4020MF,” “ShockwaveBR,” “Radar II Brand,” “Adrenalin,” “Algonquin,” “Meritbrand,” “Alfalfa-short term,” and “Certified organic”), 6 cultivars imported from China (“ShanBei,” “XinJiangDaye,” “AoHan,” “GanNong No. 3,” “Zhong Mu No.1,” and “LaoBo”), 8 cultivars imported from the USA (“San De Li,” “WL319HQ,” “HuangHou,” “Jin Huang Hou,” “Xun Lu,” “A Er Gang Jin,” “Vernal,” and “Natsuwakaba”), 1 cultivar imported from France (“42IQ”), and 1 cultivar imported from Mongolia (“Burgaltai”). The cultivars were arranged in the experimental site using a randomized block design with three replicates. Before sowing, N–P₂O₅–K₂O fertilizers were applied at a concentration of 80–200–70 kg/ha, respectively, and additional fertilizers were applied immediately after mowing to maintain favorable growth conditions. Subsequently, 50 kg/ha of K₂O was applied before winter. Weeds were removed manually, and pests were controlled using pesticides such as indoxacarb, sulfoxaflor, and pyrethroid.

2.2. Analyses of Growth Characteristics, Productivity, and Feed Value

The average height (cm) and length (cm) of each alfalfa cultivar was measured on the day of harvesting by measuring the height and length of each plant from the ground to the topmost part of the plant. Diseases and insect damage were evaluated on the day of harvesting and expressed on a scale of 1 to 9 (the closer to 1, the greater the damage). Each cultivar was harvested four times a year at the early flowering stage. After harvesting, 300–500 g of plant samples was collected, weighed to estimate the fresh matter yield (FMY), and dried in a circulating air-blast dryer at 60°C for >72h. Subsequently, the dry matter ratio (DMR) was estimated, and the dry matter yield (DMY, kg/ha) was calculated by multiplying FMY with DMR. The feed value, including acid detergent fiber (ADF), neutral detergent fiber (NDF), crude protein (CP), digestibility, and total digestible nutrients (TDN), of each cultivar was estimated using the samples collected on the day of harvesting. The ADF and NDF values were estimated using the method described in [16]. Furthermore, the relative feed value (RFV) was calculated using the digestible dry matter (DDM) and dry matter intake (DMI), and the CP and TDN content was estimated using the method described by [17] and the formula derived in [18], respectively. The in vitro dry matter digestibility (IVDMD) value was estimated using the method described in [19] and modified in [20].

[picture] | (1)

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3. Results and Discussion

3.1. Growth Characteristics

The average plant height and length of 26 alfalfa cultivars are shown in Table 1. “Xun Lu” (47.06 cm) was significantly taller than all other cultivars used in this study (p < 0.05), and the average height of all the cultivars cultivated for three years was 40.42 cm. Although the cultivar “Vernal” exhibited normal germination, the seedling was not robust and showed poor growth.

As alfalfa has high tensile strength, its length is measured to a higher point than its height. The average length of the 26 alfalfa cultivars used in this study was 72.37 cm, and “GanNong No. 3” (79.71 cm) was significantly longer than other cultivars (p < 0.05), similar to the results in [21], which revealed that when alfalfa was mowed four times a year, the average height of first-mowed alfalfa was 94 cm, which decreased to 43 cm on average over the years.

The plant height and length of alfalfa are the key determinants of productivity; cultivars with greater height and length exhibit high productivity. However, taller alfalfa cultivars are vulnerable to aphids and other insects because of lodging and microclimatic conditions.

Table 1. Growth characteristics of the 26 alfalfa (Medicago sativa L.) cultivars cultivated at the experimental site

3.2. Productivity

Table 2 shows the productivity of the 26 alfalfa cultivars estimated from 2016 to 2018. In 2016, the FMYs of the cultivars “Vernal” (40,050 kg/ha) and “Natsuwakaba” (177,333 kg/ha) were the lowest and highest, respectively, showing a significant difference from those of other cultivars (p < 0.05). In addition, the FMYs of “Alfalfa short” (149,500 kg/ha) and “Adrenalin” (148,333 kg/ha) in 2017 were significantly higher than those of other cultivars (p < 0.05). The average FMY of all cultivars in 2018 was 120,272 kg/ha, similar to that in 2017 (128,578 kg/ha). In 2018, “Natsuwakaba” exhibited the highest FMY, while “ShanBei” exhibited the lowest FMY (p < 0.05). However, the seeds of “Vernal” exhibited poor vitality. Furthermore, the average FMY of the 26 alfalfa cultivars cultivated in Cheonan-si in 2018 was 103,945 kg/ha, which was the lowest of the three years. In 2019, “Natsuwakaba” exhibited the highest average FMY of 157,844 kg/ha/year, demonstrating the greatest adaptability to the conditions in the Cheonan-si region. In addition, the stable FMYs of “4020MF,” “Algonquin,” and “Meritbrand” throughout the study period suggested that they are better suited for the environmental conditions of South Korea. In contrast, after three years of cultivation in South Korea, the FMYs of “ShanBei” (78,999 kg/ha) and “AoHan” (86,677 kg/ha) were significantly lower than those of the other cultivars (p < 0.05), indicating that these cultivars had the lowest environmental adaptability.

Alfalfa demonstrates vigorous root growth and high atmospheric nitrogen fixation under normal growth conditions [22,23,24]. Thus, the differences in the productivity of each cultivar evaluated in this study can be attributed to the ability of each cultivar to adapt to the local soil conditions and cultivation strategy. As alfalfa is a perennial legume, it can be harvested for several years after a single sowing. However, it must be re-sown periodically to ensure high yields. Thus, further investigations are necessary to determine the appropriate period between two sowing events, which can be determined using the changes in the cultivar productivity from one year to the next.

Although the alfalfa cultivars were cultivated during the same period, the DMR of each cultivar was different, leading to similar yet different DMY values. The average DMY of the 26 cultivars cultivated during 2017 was 30,851 kg/ha. The DMY of “Natsuwakaba” (42,411 kg/ha) was the highest among all cultivars (p < 0.05), whereas, the DMYs of “421Q” (35,153 kg/ha) and “Alfalfa-short” (35,430 kg/ha) were significantly lower than that of “Natsuwakaba,” but significantly higher than that of other cultivars (p < 0.05). In contrast, “Certified organic” and “ShanBei” exhibited the lowest DMYs in 2016 (p < 0.05).

The average DMY of the alfalfa cultivars in 2018 was 25,732 kg/ha. A previous study by McDonald et al. [25] showed that the annual DMY of alfalfa ranged from 18.8 to 19.8 t/ha, irrespective of its dependence on the amount of the nitrogen fertilizer. However, these observations were lower than those of this study. In 2017, the DMY of “Natsuwakaba” (35,185 kg/ha) was significantly higher than that of other cultivars (p < 0.05), indicating higher productivity owing to its superior wintering and regenerative abilities in the Cheonan-si region, while that of “ShanBei” (13.329 kg/ha) was the lowest (p < 0.05).

The average DMY of alfalfa in 2019 (25,688 kg/ha) was slightly lower than that in 2018. Although “Natsuwakaba” showed significant statistical differences from other cultivars in the second year, no significant differences between “Natsuwakaba” and other cultivars were observed in the third year; the DMY of “Natsuwakaba” (33,654 kg/ha) was not significantly different from that of “Radar II Brand” (32,797 kg/ha) (p < 0.05). Among all the alfalfa cultivars cultivated in in this study for three years, the average DMY of “Natsuwakaba” was significantly higher (p < 0.05). In addition, the average DMYs of “Radar II Brand” (31,163 kg/ha) and “WL319HQ” (31,851 kg/ha) were lower than that of “Natsuwakaba” but relatively higher than that of other cultivars.

3.3. Feed Value

The feed values of the 26 alfalfa cultivars are given in Table 3 and Table 4. A high feed value during the early flowering period is an important determinant for selecting alfalfa cultivars. The ADF content in the 26 alfalfa cultivars ranged from 38.9% to 46.26%, with an average of 42.10%. These results are similar to those of [26], which revealed that the average ADF content of each cultivar after the first harvesting was 40.27%. In this study, “Jin Huang Hou” exhibited the lowest ADF content (38.9%) (p < 0.05). In contrast, the highest ADF content was estimated for “Burgaltai” (46.26%, p < 0.05). Furthermore, DDM and TDN content estimated using the ADF content showed a similar trend.

The average NDF content of the 26 alfalfa cultivars was 52.09%, and the NDF content of “Jin Huang Hou” (47.26%) was significantly higher than that of other cultivars (p < 0.05), while that of “4020MF” was the lowest (54.27%). The ADF and NDF content of all alfalfa cultivars did not show significant differences in the growth characteristics and productivity. The NDF content of alfalfa in this study was relatively higher than that reported by a previous study (43.3%) [26]. However, the three-year-average NDF content of alfalfa harvested during the early flowering period (2011-2013) was 54.9-60.1%, which was similar to that reported by [27].

“Jin Huang Hou” had the highest DMI value of 2.56%, and the average CP content of the 26 alfalfa cultivars was 17.02%. Moreover, the CP content of the 26 cultivars were significantly higher than their ADF and NDF contents (p < 0.05). The CP content of “Certified organic” (19.44%) and “Jin Huang Hou” (19.31%) was significantly higher than that of other cultivars (p < 0.05). The CP content of alfalfa varies with the time of mowing. Based on [28], the average CP content of seven alfalfa cultivars in northern Bulgaria was 19.78%, which is in line with the results of the present study. The CP content of “4020MF” (14.95%) was significantly different from that of other cultivars (p < 0.05), indicating that this cultivar is not suitable for the environmental conditions in South Korea. The IVDMD of “Shockwave BR,” “Certified organic,” and “Jin Huang Hou” was significantly higher than that of other cultivars (p < 0.05), and “Jin Huang Hou” exhibited the highest in vitro digestibility of 74.56%.

Table 2. Forage productivity of the 26 alfalfa (Medicago sativa L.) cultivars cultivated at the experimental site

Table 3. Feed values (ADF, NDF, CP, and IVDMD) of the 26 alfalfa (Medicago sativa L.) cultivars cultivated at the experimental site

Table 4. Feed values (DDM, DMI, RFV, and TDN) of the 26 alfalfa (Medicago sativa L.) cultivars cultivated at the experimental site

4. Conclusions

Poaceae species are the primary forage crops cultivated in South Korea. However, few studies have investigated the cultivation of local legume species, particularly alfalfa, which are necessary for the self-sufficient production of high-quality forage legume crops in South Korea. Therefore, intensive investigations are necessary to increase the diversity in domestic pastures and to enhance feed resources. This study was conducted to identify alfalfa cultivars that are the most suitable for cultivation in South Korea by cultivating 26 alfalfa cultivars in the local environment for three years. Among the 26 cultivars of alfalfa, “Natsuwakaba” cultivated in the Cheonan-si region exhibited the highest three-year-average DMY of 37,083 kg/ha. However, “Certified organic,” “Jin Huang Hou,” and “Shock wave BR” had higher ADF, NDF, and CP contents and higher in vitro digestibility compared to the other cultivars. Although the feed value of “Jin Huang Hou” and “Certified organic” cultivated in central region in South Korea was high, “Natsuwakaba” showed the best results in terms of both productivity and feed value.

Acknowledgements

This study was supported by the Cooperative Research Program for Agriculture Science & Technology Development (Project No. PJ01592501) and the 2021 collaborative research program between the university and the Rural Development Administration, Republic of Korea.

Conflict of Interests

The authors declare no conflict of interests.

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