Ⅰ. INTRODUCTION
Triticale (× Triticosecale Wittmack) is a polyploid that results from chromosome doubling in a hybrid of wheat and rye (Mergoum et al., 2004;Hills et al., 2007). Hexaploid triticale (AABBRR) is the result of crossbreeding durum wheat (Triticum turgidum ssp. durum, AABB) and rye (Secale cereale, RR) (Oettler et al., 2003). Triticale is the result of multiple crossbreeding events with wheat, which have been undertaken in order to combine desirable agronomic traits. Consequently, it exhibits characteristics intermediate between those of wheat and rye. However, it has been observed to exhibit a greater degree of resemblance to its maternal parent, wheat (Kavanagh et al., 2010;Kavanagh and Hall, 2015).
As triticale is a self-pollinating crop (Goral et al., 2015), farmers can collect their own seeds. It is resistant to cold, wet injury, and lodging, and highly adaptable to various environments (Mergoum et al., 2009;Lonbani and Arzani, 2011). Reports indicate that, in terms of forage productivity, triticale dry matter yields are similar to or higher than those of wheat, barley and oats (Brown and Almodares, 1976;Bishnoi and Patel, 1979;Chiba, 1983), and that silage yields are higher than those of other cereals, such as rye (Bishnoi et al., 1978;Bishnoi and Patel, 1979;Han et al., 2012). As Bishnoi and Hughes (1979) also reported, triticale plants have been found to contain a higher protein content than that of wheat or rye. According to Kim et al. (2017), winter crops such as oats, rye, triticale, and wheat each have distinct characteristics in terms of harvest timing and yield; therefore, mixing them in a rotation to optimize growth and development can maximize seasonal forage production. Although the forage productivity of triticale varies depending on several factors, such as variety, growing conditions, and harvest time (Kim et al., 2022), it is true that triticale offers significant advantages as a forage crop.
According to Kim et al. (2017), a discernible distinction emerges in the characteristics of winter crops, including oats, rye, triticale, and wheat, with respect to harvest timing and yield. Consequently, the optimisation of growth and development through mixed cropping can maximise seasonal forage production. As demonstrated in the study by Kim et al. (2022), yield is subject to variation due to a number of factors, including variety, growing conditions, and harvest timing. Despite this, triticale has been shown to possess significant advantages as a forage crop.
In Korea, triticale has been proven to yield high and stable harvests, and it is rapidly replacing rye-a major winter forage crop-(Kim et al., 2020); in some regions, it is being cultivated as a regionally specialized crop (Nongmin, 2022). Starting with the development of the "Shinkihomil" variety in 1985 (Youn et al., 1986), several varieties have been developed, including the early-maturing "Joseong" (Han et al., 2012). However, triticale varieties developed in Korea still lack diversity in terms of appearance, maturity, and winter hardiness, and since varieties with high lodging resistance suitable for high-density cultivation on limited farmland have not been developed, the range of varieties available to livestock farmers remains narrow.
This study aims to report the breeding of a forage and silage triticale cultivar that achieves higher forage yield, superior cold tolerance, improved lodging resistance, and higher crude protein content compared to existing cultivars.
Ⅱ. MATERIALS AND METHODS
1. Background of development
"Minpung" is a forage triticale variety that was developed in 2016 at the National Institute of Crop Science (NICS), RDA in Suwon. The development of this variety was driven by the necessity to facilitate winter cultivation in the central and northern regions, a feat made possible by its ability to withstand cold conditions and its propensity to produce a high number of tillers. Crossbreeding was conducted in 2003 at the NICS in Suwon between the elite lines CTSS92B00968F-B-4M-1Y-0Y-0B and CTSS92B00380S-8Y-0Y-0B, which were introduced from CIMMYT. The process of artificial hybridization was followed, resulting in the selection of a high-generation line designated "STO3038-B-9-5-3-7-7-3" based on its superior agronomic traits, particularly its suitability for forage use. Productivity trials were conducted over a two-year period from 2012 to 2013. The designation of this line as "Iksan No. 48" was made on the basis of its proven resilience to natural disasters and its notable dry matter yield. Subsequent regional adaptation trials were conducted nationwide, including in Jeju, Iksan, Cheongwon, Yesan, Gangjin, Daegu, and Jinju, over a three-year period from 2014 to 2016. The results demonstrated that "Iksan No. 48" exhibited enhanced resistance to adverse conditions, including cold and lodging stresses, in comparison to existing varieties. In addition, it exhibited superior forage yield potential. In August 2016, the Committee for the Selection of New Varieties from Official Breeding Programs at the Rural Development Administration officially designated it as a breeding variety and named it "Minpung" (Fig. 1).
2. Test method
Regional yield trials were conducted as upland crops in Cheongwon, Yesan, and Jeju, and as paddy crops in Iksan, Gangjin, Jinju, and Daegu, respectively. The sowing dates were as follows: mid-October in Cheongwon, Yesan and Daegu, late October in Iksan, Gangjin and Jinju, and early November in Jeju. Seeds were sown using the drilling method at a spacing of 25 cm × 5 cm (ridge width × seeding width) in upland, and by broadcasting method at a spacing of 150 cm × 120 cm in paddy fields. The seeding rate was 180 kg ha−1 for dry fields and 220 kg ha−1 for paddy fields. Fertilizer application rates were determined based on soil analysis, using the standard application rates of 118 kg ha−1 of nitrogen, 74 kg ha−1 of phosphorus, and 39 kg ha−1 of potassium as a reference. The nitrogen was divided into two equal parts, with one part applied as a basal application and the other part applied as a topdressing, and the phosphorus and potassium were administered exclusively as basal applications. The harvesting process was executed approximately 30 days after heading, involving the extraction of the entire aboveground biomass. Fresh yield was calculated by harvesting test plots and converting the results into yield per hectare. Dry matter yield was calculated by weighing each fresh sample, taking a 1 kg portion, drying it for 60 hours in a recirculating forced-air dryer at 70 °C, determining the dry matter content and multiplying this by the fresh yield to convert it to yield per hectare. The dried samples were ground using an electric mixer and stored in a cold storage room at 4°C for use in forage analysis. All other cultivation management practices adhered to the standard methods of the Rural Development Administration (RDA). Growth, yield characteristics, cold hardiness and resistance to pests and diseases were assessed in accordance with the survey criteria outlined in the RDA's project implementation plan for the Joint Research Project on New Variety Development (RDA, 2015). The forage quality of the breeding lines was evaluated by analysing crude protein using the AOAC method (1995), and NDF (neutral detergent fiber) and ADF (acid detergent fiber) were analysed using the Goering and Van Soest method (1970). The TDN content was calculated using the formula (Holland, 1990).
Ⅲ. RESULTS AND DISCUSSION
1. Inherent characteristics
The following Table 1 illustrates the distinguishing characteristics of the newly developed triticale variety, "Minpung": "Minpung" is characterised by the possession of 42 chromosomes. The variety was found to have green leaves, a medium-thick stem, yellow spikes, and yellowish-brown seeds, which were found to be similar to those of the standard variety "Shinyoung". However, in comparison to "Shinyoung", it exhibits a slightly narrower leaf width, a yellow stem, a comparatively shorter spike, and larger grains. According to Ammar et al. (2004), the widely cultivated triticale varieties around the world today are hexaploid plants created through interspecific hybridisation between common wheat (autogamous) and rye (allogamous). They possess the characteristic of reliably producing seeds.
2. Plant height and heading date
As shown in Table 2, the mean height of the "Minpung" plant across all test sites was 125 cm. This was found to be marginally taller than the 121 cm recorded for the standard variety "Shinyoung", though the difference was not found to be statistically significant (p>0.05). The plants were tallest in Jeju at 137 cm and shortest in Jinju at 111 cm. The standard variety, designated "Shinyoung", exhibited comparatively elevated stature in Gangjin at 126 cm, and comparatively diminished stature in Jinju at 111 cm, thereby manifesting regional disparities that deviated from the trend observed for "Minpung".
As shown in Table 2, the mean heading date for "Minpung" across all regional adaptation trial sites was April 22, which corresponded to the standard variety "Shinyoung" (p>0.05). Evaluated by region, the heading date of "Minpung" was the earliest in Jeju, averaging March 30, and the latest in Yesan, on April 30, showing a 30-day difference between Jeju and Yesan. The standard variety, designated "Shinyoung", exhibited the earliest heading date in Jeju (April 2) and the latest in Yesan (April 30). The discrepancy between the earliest and latest regions was found to be 28 days, suggesting that the variation exhibited by the former was marginally less pronounced in comparison to that of "Minpung". Brouwer (1977) posited that the response of triticale to temperature and photoperiod regarding heading and maturity was quantitative. It was reported that these stages were shortened as the average daily sunshine duration increased or the average daily temperature rose at each growth stage. In this study, heading occurred earlier in the relatively warmer southern regions, regardless of the variety's winter hardiness.
3. Stress tolerance
The cold hardiness of "Minpung" was evaluated in regional adaptation trials conducted in seven locations, including Jeju, Iksan, Cheongwon, Yesan, Gangjin, Daegu, and Jinju. The average rating across the trial sites was 1. This finding is indicative of a strong cold resistance capacity, as evidenced in Table 3. In addition, the lodging to resistance was evaluated at 1, which is indicative of greater strength in comparison to the 2 recorded for the standard variety, "Shinyoung". It was observed that neither "Minpung" nor "Shinyoung" exhibited any indications of damage resulting from wet injury, powdery mildew, or leaf rust. As reported by the AAFRD (2005), triticale has been demonstrated to show a high degree of adaptability to a variety of environmental stresses, including conditions of drought and wet injury. The "Minpung" variety exhibited a high level of resistance to wet injury and diseases that occur in the paddy field cultivation environment of domestic forage crops. In Korea, where cereals are cultivated as a secondary crop in paddy fields during the winter season, the process of overwintering is of paramount importance to ensure optimal productivity (Polishchuk et al., 2024). It is anticipated that "Minpung" will prove advantageous for forage production using fallow land in the winter season, given its strong cold tolerance.
4. Forage productivity
The mean fresh yield per hectare of "Minpung", ascertained 30 days following heading, was 45.9 MT ha−1 across all trial sites, as demonstrated in Table 4. This yield was found to be 6% higher than the 43.5 MT ha−1 recorded for the standard variety "Shinyoung" (p<0.05). The highest recorded fresh yields per hectare for "Minpung" were observed in Gangjin (64.9 MT ha−1), Jeju (53.3 MT ha−1), and Jinju (52.3 MT ha−1). The results demonstrated that these regions exhibited yield potential that was 17%, 12%, and 6% higher than that of the standard variety "Shinyoung", respectively. However, the fresh forage yields of "Minpung" were comparatively lower in the Yesan, Iksan, and Daegu areas, at 39.2, 36.8, and 32.2 MT ha−1, respectively. In the Yesan area, the yield of "Minpung" was approximately 9% lower than that of the standard variety.
The mean dry matter yield was 17.2 MT ha−1 across all test sites, which was 4% higher than the standard variety, "Shinyoung" (p<0.05). Gangjin and Jeju demonstrated the highest dry matter yields per hectare at 26 and 20.7 MT ha−1, respectively, while Iksan and Daegu exhibited the lowest at 13.2 and 11.4 MT ha−1, respectively. A comparison of the yield of "Minpung" with that of the standard variety revealed a 17% increase in Gangjin, a 10% increase in Jinju and Jeju, and a 15% decrease in Yesan. As mentioned in the previous sentence, "Minpung" had higher forage yields than "Shinyeong" in four regions. However, it was also confirmed that there were regional variations. As McGoverin et al. (2011) reported, the forage yield of triticale is the result of an interaction between genetic and environmental factors. It is therefore logical to deduce that high yields can be expected when these conditions are favourable. Consequently, while "Minpung" exhibits considerable yield potential, it is imperative to exercise meticulous consideration with respect to the prevailing growing environment.
5. Feed value
Table 5 shows the forage quality characteristics of "Minpung", which were evaluated based on the entire aboveground biomass harvested 30 days after heading in Iksan, Jeonbuk. The crude protein content of "Minpung" was found to be 6.7%, which is 0.5% higher than the standard variety "Shinyoung" (6.2%) (p<0.05). Furthermore, the acid detergent fibre (ADF) and neutral detergent fibre (NDF) contents were 34.2% and 56.0%, respectively; these values were higher than those of "Shinyoung" (32.9% and 55.1%, respectively) (p>0.05). The total digestible nutrients (TDN) content was 61.9%, which was marginally lower than the 62.9% of "Shinyoung", and the TDN yield was 8.1 MT ha−1, which was lower than the 8.4 MT ha−1 of "Shinyoung"; however, these differences were not statistically significant (p>0.05).
6. Seed Productivity
Given that forage triticale is employed as a whole-crop forage source and the seeds are not harvested post-cultivation, the demand for seeds is elevated. Consequently, the evaluation of grain yield assumes significant importance. As shown in Table 6, the maturity period, yield components and grain yield per unit area for "Minpung" are presented. In comparison to "Shinyoung", "Minpung" exhibits a marginally diminished spike length (8.9 cm) and exhibits lower values for yield components, including the number of spikes and grains per unit area. However, it should be noted that the 1,000-grain and 1-liter weights are higher (p<0.05). Consequently, the grain yield was 5.72 MT ha−1, which is comparable to Shinyoung's yield of 5.75 MT ha−1.
7. Suitable Regions and Cultivation Considerations
The newly developed triticale variety, designated as "Minpung", has been shown to possess the capacity to undergo winter survival in regions where the average minimum January temperature is -10°C or higher. Consequently, it can be cultivated for a winter harvest in all regions except northern Gyeonggi Province, Gangwon Province, and some mountainous areas of North Gyeongsang Province, where winters are protracted and temperatures are low.
However, early sowing may result in frost damage due to excessive growth before overwintering. It has been demonstrated that areas subject to extreme daily temperature fluctuations during the recovery growth period in mid- to late February are also susceptible to frost damage. In order to ensure timely sowing and to guarantee adequate plant density, farmers are advised to adhere to the standard cultivation methods for their region. Such methods include proper management after emergence and overwintering, including drainage management and trampling the plants.
Ⅳ. CONCLUSIONS
The triticale variety "Minpung", which was developed in this study, lacks the early maturity necessary for double-cropping in Korea. However, it demonstrated cold tolerance, an essential characteristic for a winter crop, and resistance to waterlogging in paddy fields. Furthermore, its forage productivity was higher than that of standard varieties. These results suggest its high potential for use as a forage crop in various regions prior to rice transplanting. To further enhance the variety’s utility, however, its maturity period must be shortened through breeding. It was concluded that ongoing research in this area is necessary.










