Breeding report of two new Torreya grandis cultivars Meirenzhi and Zaozhenzhu

Abstract: Meirenzhi and Zaozhenzhu are two new cultivars selected from adult seedling trees of Torreya grandis in Shengzhou county of Zhejiang province in 2023. The progenies were cultivated by grafting method. Meirenzhi was initially found and selected in 2012 for its thin seed shell and excellent processing flavor, and Zaozhenzhu was initially found and selected in 2015 for its extremely thin shell, early anthesis and excellent processing flavor. The maternal plants of both Meirenzhi and Zaozhenzhu were discovered in two villages of Gulai town, Shengzhou county. The planting of Meirenzhi and Zaozhenzhu was expanded in 2013 and 2017 by grafting method, respectively. And the DUS testing was completed in November 2023. Finally, the two new cultivars of T. grandis were successfully registered in December 2023 after several years selection. The two cultivars are both tall and vigorous trees, whose crown shows a circular or semicircular shape with a height of 10-15 m. Meanwhile, the grafting progenies crown of Zaozhenzhu shows more compact and upright compared with Meirenzhi. Leaves of both cultivars are linear lanceolate. For Meirenzhi, the average leaf length and width are 2.15 cm and 0.32 cm, respectively. And for Zaozhenzhu, they are 2.12 cm and 0.31 cm, respectively. The upper epidermis of their leaves are dark green and the lower epidermis are light green. Both of the two cultivars are dioecism plants, the floral bud of female plant is a mixed bud. The seed with arillus encircled is drupaceous. The seed of Meirenzhi shows a nearly ovoid shape with thin nut, and the seed of Zaozhenzhu shows a spherical shape with nearly ovoid nut. And they are different from the shape of seeds of T. grandis‘Xifei’. The milky white fleshy roots usually distribute in the loose and ventilate soil at 10-50 cmunderground. For Meirenzhi, the average mass of fresh seed is 10.77 g, and the average vertical and horizontal diameters of seeds are 3.81 cm and 2.25 cm, respectively. The average shape index of seeds is 1.69. The average ratio of fresh nut to seed is 26.8%. The mean weight of fresh nut is 2.89 g. The mean vertical and horizontal diameters of nuts are 3.46 cm and 1.26 cm, respectively. The mean shape index of nuts is 2.74. The mean ratio of dry kernel to nut is 72.54%. The oil content of dry kernel is 59.1%. The contents of soluble sugar and protein are 2.94% and 13.1%, respectively. For Zaozhenzhu, the average mass of fresh seed is 7.98 g, and the average vertical and horizontal diameters of seeds are 2.52 cm and 1.44 cm, respectively. The average shape index of seeds is 1.21. The average ratio of fresh nut to seed is 33.7%. The mean fruit weight of fresh nut is 2.68 g. The mean vertical and horizontal diameters of nuts are 2.48 cm and 1.42 cm, respectively. The mean shape index of nuts is 1.75. The mean ratio of dry kernel to nut is 78.68%. The oil content of dry kernel is 57.6%. The contents of soluble sugar and protein are 4.17% and 11.0%, respectively. The seed quality is excellent and the product performance is good. The market application prospect is broad in the future. In addition, the anthesis period of Meirenzhi is in early April, and the mature period is in early September of next year. The anthesis period of Zaozhenzhu is in late March, and the mature period is in early October of next year. The seedlings and young trees of both cultivars prefer cool and damp environments and fear high temperature, drought, waterlogging and intense sunlight. The mature trees show better environmental adaptability compared with young tress, which are resistant to cold, heat and slight drought to some extent. It shows good uniformity and stability by progeny testing, and the shape of seed and kernel quality are consistent with those of maternal plants. Their cultivation techniques are the same as T. grandis Xifei. It is suitable for cultivation throughout the distribution areas of wild T. grandis besides Zhejiang. The two cultivars need sandy and fertile soil with the pH value from 5.0 to 7.5. We suggest that 400-600 seedlings per hectare should be planted. The managements should focus on rational fertilization, efficient soil loosening, scientific pruning and integrated management of pests and diseases.