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ISSN : 1225-8504(Print)
ISSN : 2287-8165(Online)

Journal of the Korean Society of International Agriculture Vol.34 No.1 pp.67-72
DOI : https://doi.org/10.12719/KSIA.2022.34.1.67

A New Late-maturing Variety of Italian Ryegrass (Lolium multiflorum Lam.), ‘IR901’, with High Forage Productivity in the Southern Region of South Korea

Ki-Yong Kim^*

, Ki Won Lee^*, Sang Hoon Lee^*, Gi Jun Choi^*, Hyung Soo Park^*, Hee Chung Ji^*, Yo-Soon Jang^**†

, Tae-Young Hwang^***†

^*National Institute of Animal Science, RDA, Cheonan, 31000, Republic of Korea
^**East Sea Environment Research Center, KIOST, Uljin, 36315, Korea
^***Department of Crop Science, Colleage of Agriculture, Chungbuk National University, Cheongju, 286344, Republic of Korea

These authors contributed equally to this article.

^† Corresponding author (Phone) +82-43-261-2511 (E-mail) hwangty@chungbuk.ac.kr
^† Co-Corresponding author (Phone) +82-54-780-5326 (E-mail) jangys@kiost.ac.kr

Received February 8, 2022 Review March 2, 2022 Accepted March 5, 2022

Abstract

This study was conducted at the National Institute of Animal Science (NIAS) from 2010 to 2017 to develop a late-maturing variety with high productivity for cultivation in the southern region of South Korea. The new variety of Italian ryegrass, ‘IR901’, was a late-maturing variety, and its heading date was 22 May, 17 days later than that of the control variety ‘Kowinearly’. ‘IR901’ had a flag leaf width of 11.2 mm, flag leaf length of 31.8 cm, and plant length of 103 cm on its heading date. The combined average dry matter yield of ‘IR901’ in all three adaptability evaluation regions (Cheonan, Pyeongchang and Haenam) was 7,747 kg/ha, which was similar to that of the ‘Kowinearly’ variety (7,734 kg/ ha). However, the average dry matter yield over three years in Cheonan and Pyeongchang was 82% and 96%, respectively, compared to that of the control, which was most likely because of the poor cold tolerance of ‘IR901’. By contrast, in Haenam, in the southern region, the average dry matter yield of ‘IR901’ was 19% higher than that of the ‘Kowinearly’ variety. The proportions of crude protein (CP), total digestible nutrients (TDN), acid detergent fiber (ADF), and neutral detergent fiber (NDF) in ‘IR901’ were 8.6%, 59.7%, 36.9%, and 54.8%, respectively; the proportions were 0.2% lower, the same, the same, and 2.5% lower than those in the ‘Kowinearly’ variety. The determined in vitro dry matter digestibility (IVDMD) of ‘IR901’ was 72.2% higher than that of ‘Kowinearly’ (67.2). In general, of the two varieties, the forage quality of ‘IR901’ was marginally superior to that of ‘Kowinearly’.

Key Words : Italian ryegrass , Late maturing , New variety , IR901

남부지역에서 조사료 생산성이 높은 이탈리안 라이그라스 만생종 신품종 ‘IR901’

김기용^*

, 이기원^*, 이상훈^*, 최기준^*, 박형수^*, 지희정^*, 장요순^**†

, 황태영^***†

^*농촌진흥청 국립축산과학원
^**한국해양과학기술원 동해환경연구센터
^***충북대학교 농업생명과학대학 식물자원학과

초록

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INTRODUCTION

Historically, winter forage crops cultivated in paddy fields have been mainly located in the southern regions of Korea (Lee et al., 2020;Kim, 1991). In particular, Jeollanam- do and Jeollabuk-do account for 54.6% (33,865 ha) and 20.5% (12,737 ha) of the total forage crops cultivated in domestic rice paddies, respectively (MAFRA, 2020a). Italian ryegrass (Lolium multiflorum Lam., IRG) has been cultivated in the south, as it is a suitable paddy field crop. Moreover, domestic farmers have preferred to cultivate it because of its excellent livestock feed value and palatability and its capacity to grow under wet soil conditions (Lee et al., 2020;Kim et al., 2021). IRG can be used as freshcut fodder, silage, or hay, and among them, silage is popular in the southern part of Korea (Sung et al., 2012;Peng et al., 2016).

In the past decade in Korea, the cultivated area of IRG has increased by 300% (from 52,000 to 165,000 ha), which accounts for 87% of the total winter forage crop production (MAFRA, 2020b). Owing to the high palatability, feed value, and resistance to excessive-moisture injury of this species, cultivation in paddy fields is advantageous, and it has increased over time. In order to expand the safe cultivation area of IRG in Korea from the southern to central and northern regions, and to increase productivity per unit area, cold-tolerant varieties were developed (Choi et al., 2018). The main varieties include ‘Hwasan 101’ (Choi et al., 2000), ‘Hwasan 104’ (Choi et al., 2005), and ‘Kowiner’ (Choi et al., 2006a), which are late-maturing varieties; ‘Kowinmaster’ (Choi et al., 2008) and ‘IR605’ (Kim et al., 2020), which are middle-maturing varieties; and ‘Kogreen’ (Choi et al., 2006b), ‘Kospeed’ (Choi et al., 2007), ‘Kowinearly’ (Choi et al., 2011), and ‘Greenfarm’ (Ji et al., 2011), which are early-maturing varieties.

However, the seed self-sufficiency rate of IRG was as low as 31% in 2019 (NIAS, 2019) and mainly based on cold-tolerant varieties. Consequently, there was a need to develop IRG varieties suitable for cultivation under different climatic conditions in Korea to increase the seed selfsufficiency rate of this crop. The IRG cold-tolerant variety ‘Kowinearly’ was developed in 2011 to promote cultivation in the central and northern regions of Korea, where conditions for cultivation are not optimal. However, there remained a need to develop a late-maturing variety with high productivity for cultivation in the southern and warm region. Therefore, this study was conducted to secure variety diversity in preparation for the predicted climate change in the southern region with excellent adaptability and high dry matter (DM) yield and to broaden consumer choices.

Materials and Methods

Plant Material

The IRG varieties used in the experiment were ‘IR901’ and ‘Kowinearly’ (standard variety in Korea). ‘IR901’ is a late-maturing variety that was developed by the National Institute of Animal Science (NIAS) at the Rural Development Administration (RDA) in 2019.

From 2010 to 2011, five superior IRG lines, 12EtHN4NN14, 12EtHN4NN23, ARIXJN09, ARIXJN14, and ARIXJN18, were selected and polycrossed to develop the ‘IR901’ variety (lineage name ARX 7) (Fig. 1).

Combined Line Production

In 2012, production of seeds from the ARX 7 seeds was accomplished using the polycross triangular placement method. IRG ‘ARX 7’ was cultivated in an isolated field to prevent the intrusion of external pollen, and the seeds were produced.

Field Investigation

The productivity test evaluation of ARX 7 was conducted in a Cheonan experimental field in 2014, and from 2015 to 2017, the regional adaptability evaluation was conducted as part of the RDA’s novel variety development research in three regions: Cheonan (N 37°32’56”, E 128°26’20”), Pyeongchang (N 36°56’05”, E 127°05’42”), and Haenam (N 34°41’26”, E 126°24’47”) counties in the central, northern, and southern regions of Korea, respectively. The domestic variety ‘Kowinearly’ was selected as the control variety. The sowing periods by region were the end of September in Cheonan, the middle to end of September in Pyeongchang, and early October in Haenam. The seeding rate was 30 kg/ha using 20 cm drill seeding. Basal fertilization using N:P₂O₅:K₂O at 40:75:75 kg/ha was conducted, and additional fertilizer was applied at the end of February (N:P₂O₅:K₂O at 100:75:75 kg/ha). The experimental plots were laid out according to three replications of a randomized block design, and the experimental plot size was 6 m2 (2 m × 3 m). The cold tolerance, plant length, heading date, lodging resistance, blight, and leafiness of IRG were investigated in each experimental plot during each growing season. For the evaluation of cold tolerance, plants were visually investigated and rated using a scale from 1 to 9 (1 = strong, 9 = weak).

Productivity Analysis

The investigation of productivity was conducted in the three regions used for the regional adaptability evaluation. Productivity was measured by harvesting the whole experimental plot on the heading date and using only the performance from one harvest. To calculate DM yield content, samples ranging from 300 g to 500 g were dried at 65°C for 72 h. The DM yield was calculated by multiplying the ratio of DM by fresh yield, and the value was converted to DM yield.

Feed Value Analysis

After measuring the DM yield of the samples used for the analysis of feed value, a portion of each of the three samples was taken, pulverized with a Wiley mill with a 20 mesh screen, mixed evenly, placed in a plastic container with a double stopper, sealed, and stored until analysis. The crude protein (CP) of the sample was analysed using the Association of Official Analytical Chemists (AOAC) method (1990) with Kjeltec^TM 2400 auto analyser unit (Foss Tecator, Eden Prairie, MN, USA). The acid detergent fiber (ADF) and neutral detergent fiber (NDF) content were analysed using the Goering and Van Soest (1970) method using an Ankom fiber analyzer (Ankom Technologies, Inc., Macedon, NY, USA). Total digestible nutrients (TDN) content was calculated using the 88.9 – (0.79 × ADF (%)) formula (Menke and Huss, 1980), and in vitro dry matter digestibility (IVDMD) was analysed by the method of Tilley and Terry (1963) modified by Moore (1970).

Statistical Analysis

For the statistical analysis of the data, an Analysis of Variance (ANOVA) was performed using the SAS software package (2004), and all data were subjected to analysis using Duncan’s multiple range test. Significance was set at the 5% level.

Results and Discussion

Comparison of Cold Tolerance

The average minimum air temperature and precipitation in the fields of the trial regions in December, January, and February during the IRG cultivation are shown in Table 1. In Pyeongchang, the average minimum temperature in December, January, and February ranged from -6.6 to -12.1°C, -11.2 to -12.1°C, and -9.0 to -10.1, respectively, and the precipitation ranged from 11.7 to 53.0 mm, 2.6 to 22.3 mm, and 7.2 to 38.7 mm, respectively. In January of 2016, the precipitation in Pyeongchang and Cheonan was 2.6 and 8.0 mm, respectively, and in February of 2017 in Pyeongchang and in January in Haenam, it was 7.2 and 8.8 mm, respectively, which was very well below average precipitation for these regions (National Weather Service, Korea).

The mean cold tolerance score of ‘IR901’ was 1.7, which was weaker than that of ‘Kowinearly’ (1.0) (Table 2). The foreign variety ‘Florida 80’ achieved a cold tolerance score of 3.7 from 2015 to 2017, the same period in the Cheonan region, and was evaluated to have high cold tolerance compared to ‘IR901’ (Ji et al., 2018, 2019).

Agricultural Characteristics of the Variety

The main characteristics of the new IRG variety ‘IR901’ are presented in Table 3 and Fig. 2. The new variety ‘IR901’ is diploid and has a semi-erect growth habit in autumn and an erect growth habit in spring, similar to the control variety ‘Kowinearly’. The flag leaf width and length of ‘IR901’ are 11.2 mm and 31.8 cm, respectively, which are 1.4 mm wider and 5.5 cm longer than those of ‘Kowinearly’, respectively. The stem thickness of ‘IR901’ is 0.1 mm, and the plant length on its heading date is 103 cm, which is 8 cm longer than that of ‘Kowinearly’. The leaf color of ‘IR901’ is green, similar to that of ‘Kowinearly’, and its heading date is 22 May, which is 17 days later than that of the early-maturing ‘Kowinearly’.

Forage Productivity

The DM yield of the new IRG variety ‘IR901’ is shown Table 4. The DM yields of the new variety ‘IR901’ produced in 2015, 2016, and 2017 were 9,318, 8,949, and 4,974 kg/ha, respectively, which were similar to the ‘Kowinearly’ yields of 9,829, 8,123, and 5,250 kg/ha (p < 0.05). The DM yield of the two varieties of IRG differed according to cultivation region and year. The combined average DM yield of ‘IR901’ in all three adaptability evaluation regions was 7,747 kg/ha, which was similar to that of the ‘Kowinearly’ variety (7,734 kg/ha); however, the average DM yields over the three-year trial period in Cheonan and Pyeongchang were 82% and 96%, respectively, compared to those of ‘Kowinearly’, most likely because of the poor cold tolerance of ‘IR901’. However, in Haenam, in the southern region, the average DM yield of ‘IR901’ was 19% higher than that of the control (p < 0.05).

Feed Value

The forage quality (measured as CP) of ‘IR901’ (8.6%) was similar to that of ‘Kowinearly’ (8.8%). TDN (59.7%) and ADF (36.9%) content in ‘IR901’ were the same as that in ‘Kowinearly’, whereas the NDF content was 54.8%, which was lower than that of the control variety. The forage quality of ‘IR901’ was 72.2% higher than that of ‘Kowinearly’ (67.2%) as determined by the IVDMD. In general, of the two varieties, the forage quality of ‘IR901’ was slightly better than that of ‘Kowinearly’.

This study reports on the development of a new variety of IRG with superior productivity when cultivated in the southern region of Korea. This new variety was developed to improve the Korean seed self-sufficiency rate. In 2020, a protection application for this new IRG variety developed under the variety name ‘IR901’ was submitted to the Korea Seed and Variety Service (KSVS).

적 요

본 연구는 남부 지역에서 조사료 생산성이 높은 만생종 신 품종 이탈리안 라이그라스를 개발하기 위해 2010년부터 2017 년까지 국립축산과학원에서 수행하였으며 2020년 국립종자원 에 품종보호 출원하였다.

1. 2010년부터 2011년까지 5개의 우수한 이탈리안 라이그라스 계통인 12EtHN4NN14, 12EtHN4NN23, ARIXJN09, ARIXJN14 및 ARIXJN18을 선발 후 이 계통들을 다교잡하여 새로운 합 성품종인 ‘IR901’ (계통명 ARX 7)을 개발하였다.
2. 다교잡 교배조합의 영양계통은 2012년 Polycross 삼각배 치법으로 합성포장을 조성하고, 주변에는 호밀을 재배하여 외 래 화분의 오염을 차단하고 합성계통인 ‘ARX 7’의 종자를 생 산하였다.
3. 합성계통 ‘ARX 7’의 생산력 검정시험은 2014년 천안 시험포장에서 실시하였다. 지역적응시험은 2015년부터 2017년 까지 3년에 걸쳐 농촌진흥청 신품종 개발 공동연구사업으로 천안, 평창, 해남 등 3개 지역에서 실시하였으며, 대비품종은 국산품종 ‘코윈어리’로 하였다.
4. 신품종 ‘IR901’은 2배체 작물로 엽색은 녹색이며, 월동 전 초형은 반직립형, 봄의 초형은 직립형이며, 5월 22일 출수 하는 만생종 품종이다. 지엽폭이 11.2 mm, 지엽 길이는 31.8 cm 이며, 출수기의 초장은 103 cm로 표준품종인 ‘코윈어리’보 다 8 cm 정도 길며, 줄기의 두께 및 이삭의 길이는 각각 2.67 mm, 24.0로 ‘코윈어리’보다 각각 0.1 mm 굵고, 0.5 cm 정도 길다.
5. 내한성은 ‘코윈어리’보다 약하기 때문에 남부지역(해남)이 재배 적지가 되기 때문에 조사료 건물 수량성면에서 3년 평균 9,490 kg/ha로 ‘코윈어리’(7,991 kg/ha)보다 19% 많다 (p<0.05).
6. ‘IR901’의 in vitro 건물소화율 (IVDMD)은 72.2%로서 대조품종인 ‘코윈어리’보다 5% 높았고, 가소화양분총량 (TDN) 은 59.7%로서 ‘코윈어리’와 같았다. 전반적으로 ‘아이알901’의 사료품질 특성은 ‘코윈어리’보다 약간 우수하였다.

Figure

Fig. 1.

Pedigree diagram of the Italian ryegrass variety ‘IR901’.

Fig. 2.

Comparison of plant type between Italian ryegrass varieties (A) ‘Kowinearly’ and (B) ‘IR901’, (a) after wintering, (b) heading date.

Table

Table 1.

Average minimum air temperature and precipitation from December 2014 to February 2017 in fields of trial regions of Korea.

Table 2.

Cold tolerance scores of Italian ryegrass (IRG) varieties cultivated in the trial regions of Korea from 2015 to 2017.

Table 3.

Agronomic and ear characteristics of Italian ryegrass (IRG) ‘IR901’ variety.

Table 4.

Dry matter (DM) yields of Italian ryegrass (IRG) varieties cultivated in the trial regions of Korea from 2015 to 2017.

Table 5.

Crude protein (CP), in vitro dry matter digestibility (IVDMD), acid detergent fiber (ADF), neutral detergent fiber (NDF), and total digestible nutrients (TDN) of Italian ryegrass (IRG) varieties cultivated in Cheonan from 2015 to 2017.

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