**3. Results**

### *3.1. Low-Temperature Germination Rate of Parental Lines and F2 Population*

Germination rates of four parental lines (Hwaseong, *O. rufipogon*, CR1517, and CR1518) were compared under control conditions (30 ◦C). The seeds of *O. rufipogon* began germinating at 1 DAI, with a 47% germination rate. At 4 DAI, *O. rufipogon* germination rate reached 100%. Hwaseong, CR1517, and CR1518 began germinating 2 DAI. Subsequently, the germination rate of the lines achieved nearly 100% at 4 DAI. *O. rufipogon* exhibited a significantly higher germination rate than those of other lines from 1 to 2 DAI. There were no significant differences in germination rate among the parental lines from 3 to 4 DAI under the control temperature (Figure S2). However, there were differences in the germination rate between 4 lines under the low-temperature condition (13 ◦C). *O. rufipogon* began germinating at 3 DAI and attained 100% germination rate at 7 DAI. In contrast, Hwaseong began germinating 4 DAI, and achieved 80% germination 8 DAI. Two introgression parental lines, CR1517 and CR1518, began germinating at 3 DAI, and the lines attained 85% and 94% germination rates, respectively, 7 DAI. They exhibited much more vigorous germinability than that of Hwaseong and lower than that of *O. rufipogon* (Figure S2). Germination rates in F2 plants ranged from 0 to 100% during the incubation period for 1–8 DAI (Table 1). The results revealed that *O*. *rufipogon* segments increased LTG in the Hwaseong background.


**Table 1.** Mean germination rates in *O. rufipogon*, Hwaseong, two introgression lines, and F2 population.

(x) DAI: days after incubation. Data are presented as mean germination rate or mean ± standard deviation. (y)significantdifferencesamonglineseachDAIbasedTukey's(*p*0.05).

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Different letters indicate(z) *n*:number of plants.
