The Taiwan Tea Research and Extension Station (TRES) has developed several tea cultivars to enhance tea quality and adaptability.As of May 2020, TRES has released 24 cultivars, including:

1. **TTES No. 1**: A black tea cultivar developed in 1969 by crossing Assamica from Nepal (Kyang) with Qing Xin Da-Pan.

2. **TTES No. 2**: Another black tea cultivar from 1969, resulting from a cross between Assamica from India (Jaipuri) and Da Yeh Oolong (Big Leaf Oolong).

3. **TTES No. 3**: Developed in 1969, this black tea cultivar is a cross between Assamica from India (Manipuri) and Hong Xin Da Mao.

4. **TTES No. 4**: A 1969 black tea cultivar from crossing Assamica from India (Manipuri) with Hong Xin Da-Pan.

5. **TTES No. 5**: An oolong tea cultivar developed in 1973 from a wild hybrid from Fuzhou, China.

6. **TTES No. 6**: Another 1973 oolong tea cultivar, originating from a wild hybrid of Qing Xin from Taiwan.

7. **TTES No. 7**: A black tea cultivar from 1973, derived from a big leaf varietal from Thailand, possibly Da Mao (Puer tree).

8. **TTES No. 8**: Developed in 1973, this black tea cultivar is an Assamica varietal from India (Jaipuri).

9. **TTES No. 9**: A 1975 black tea cultivar from crossing Assamica from Kyang (Nepal) with Hong Xin Da-Pan.

10. **TTES No. 10**: Developed in 1975, this black tea cultivar is a cross between Assamica from India (Jaipuri) and Huang Gan.

11. **TTES No. 11**: Another 1975 black tea cultivar, resulting from a cross between Assamica from India (Jaipuri) and Da Yeh Oolong (Big Leaf Oolong).

12. **TTES No. 12 (Jin Xuan)**: An oolong tea cultivar developed in 1981 by crossing Ying Zhi Hong Xin and TTES No. 8.

13. **TTES No. 13 (Cui Yu or Jade Oolong)**: Also developed in 1981, this oolong tea cultivar is a cross between Ying Zhi Hong Xin and Tainon-80 (TRES No. 80).

14. **TTES No. 14 (Bai Wen)**: A 1983 oolong tea cultivar from crossing Bai Mao Hou and TTES No. 983 (Huang Gan x Kyang).

15. **TTES No. 15 (Bai Yan)**: Developed in 1983, this oolong tea cultivar is a cross between Bai Mao Hou and TTES No. 983 (Huang Gan x Kyang).

16. **TTES No. 16 (Bai He)**: A 1983 oolong tea cultivar from crossing TTES No. 1958 and TTES No. 335 (Tainon-355) (Da Yeh Oolong x Kyang).

17. **TTES No. 17 (Ruan Zhi)**: Also developed in 1983, this oolong tea cultivar is a cross between TTES No. 1958 and TTES No. 335 (Tainon-355) (Da Yeh Oolong x Kyang).

18. **TTES No. 18 (Hong Yu or Ruby 18)**: A black tea cultivar developed in 1999 by crossing a Taiwanese wild tea tree (B-607) with Burmese Assamica (B729).

19. **TTES No. 19 (Bi Yu or Green Jade)**: An oolong tea cultivar from 2004, resulting from a cross between TTES No. 12 and Qing Xin Oolong.

20. **TTES No. 20 (Ying Xiang)**: Developed in 2004, this oolong tea cultivar is a cross between TTES No. 2022 (Da Yeh Oolong x Tainon-20) and Qing Xin Oolong.

21. **TTES No. 21 (Hong Yun)**: A black tea cultivar from 2008, resulting from a cross between Keemun and Nepalese Assamica.

22. **TTES No. 22**: An oolong tea cultivar developed in 2014 by crossing Qing Xin Oolong and Jin Xuan.

23. **TTES No. 23**: Details about this cultivar are limited.

24. **TTES No. 24**: Details about this cultivar are limited.

These cultivars have been developed to enhance specific characteristics such as flavor, aroma, and resistance to pests and diseases, contributing significantly to the diversity and quality of Taiwanese teas.

In Taiwan, both the Taiwan Tea Research and Extension Station (TRES) and local farmers have developed various tea cultivars to enhance quality, yield, and adaptability. While TRES has officially released several cultivars, local farmers have also contributed significantly to Taiwan's tea diversity. Notable cultivars developed or popularized by local farmers include:

1. Si Ji Chun (四季春): Also known as "Four Seasons Spring," this cultivar was developed by farmers in the Muzha area of northern Taiwan. It's prized for its ability to produce fresh, floral-flavored leaves throughout the year, even during seasons when other tea plants are less productive.
2. Qing Xin (青心): Also known as "Green Heart," this traditional cultivar was brought to Taiwan by Fujianese settlers in the 18th and 19th centuries. It remains one of the most widely cultivated varieties, especially for high-quality oolong teas.
3. Tie Guan Yin (鐵觀音): Originating from Fujian, China, this cultivar was introduced to Taiwan by early settlers. It's primarily grown in the Muzha area and is known for its rich, robust flavor.
4. Fo Shou (佛手): Known as "Buddha's Hand," this cultivar is recognized for its large leaves and strong fruity flavor. It's commonly found in the Pinglin area.
5. Bai Hao (白毫): Also known as "Oriental Beauty," this cultivar is unique due to its interaction with the tea green leafhopper, which enhances its sweet, fruity flavor. It's primarily cultivated in Hsinchu and Miaoli counties.
6. Shan Cha (山茶): This indigenous wild tea variety is native to Taiwan and has been traditionally harvested by local farmers. It's used to produce unique teas with distinct flavors.

These cultivars, developed or popularized by local farmers, have significantly contributed to the rich diversity and reputation of Taiwanese teas.