Breeding report of a new Torreya grandis cultivar Pandongfei

Pandongfei is a new variety selected from the abundant Torreya resources in Panan County, Zhejiang Province. According to the ploidy determination results obtained by flow cytometry, Pandongfei is a triploid. The crown of the parent tree is spire-shaped, with an open and vigorous growth habit. After grafting propagation, about 30 progenies in the local area have started to bear fruit. The shape, maturity period, and flavor of the seeds are consistent with those of the parent tree, showing stable genetic performance. Among them, the characteristics of the offspring are consistent and stable. The leaves are linear-lanceolate, dark green on the upper side, light green on the underside, 2.2 cm long, 0.37 cm wide and 0.07 cm thick, with longer leaf tips. The female flower bud of Pandongfei is a mixed bud, usually differentiated from the top lateral bud of the fruiting mother branch. The seed is nucleate, enveloped in a fleshy arillus. When ripe, the arillus gradually changes from green to light yellow-green. The seed is extra-large, elongated oval, with an average fresh single seed weight of 17.4 g, a longitudinal diameter of 4.26 cm, a transverse diameter of 2.53 cm, and a seed shape index of 1.69. The arillus is very thick,with an average thickness of 0.57 cm, and a fresh core rate of 27.91%. The seed kernel is long elliptical, with an average fresh single kernel weight of 4.8 g, a dry single kernel weight of 3.3 g, a longitudinal diameter of 3.83 cm, a transverse diameter of 1.49 cm, a kernel shape index of 2.58, a shell thickness of 0.12 cm, and a dry kernel rate of 54.07%. The seed kernel is long elliptical, with an average dry single kernel weight of 1.8 g, an oil content of 52.7%, a soluble sugar content (w, same as below) of 1.29%, and a protein content of 12.1%. After roasting, it exhibits easier shell removal compared to Xifei, characterized by a crisp and refreshing texture, intense aroma, and superior commercial qualities. When it is cultivated at an elevation of 300 meters in Pangan County, Zhejiang Province, its seed maturation period occurs in mid-September, slightly later than that of Xifei grown at comparable altitudes in adjacent regions. Pandongfei and Yushanguofei have extra-large seeds, but the main difference is that the number of eyes on the surface of Pandongfei seeds is generally 2, while that of Yushanguofei is 2-5, with the proportion of seeds with more than 3 eyes being 41.9%. Both the seed shape index and kernel shape index of Pandongfei are higher than those of Yushanguofei. The oil content of Pandongfei kernel is 52.7%, which is higher than that of Yushanguofei (48.1%). However, the rates of seed core extraction and kernel extraction from seeds are lower than those of Yushanguofei. This variety is high-quality, early-maturing, and stress-resistant. It prefers shade and moisture at the beginning of its growth and is not suitable for growth in low-altitude areas with intensive sunlight. After starting to bear fruit during the vegetative growth period, it needs sufficient sunlight to maintain growth, so it is appropriate to supplement lighting and increase the intensity and duration of lighting. It has good disease and pest resistance. According to surveys, the probability of diseases and pests occurring in its seedlings, saplings, and adult trees is small, and there are generally no diseases under standard management. It is suitable for cultivation in mountainous areas at altitudes of 200-800 meters in Panan County, Zhejiang Province, with the same requirements for climate, soil, and other environmental conditions as well as cultivation techniques as Xifei. After grafting propagation, a certain amount of progeny has been cultivated in Zhejiang Province, with stable genetic expression and a small portion beginning to bear fruit. The characteristics of Pandongfei include high oil content in the seed kernel, easy removal of the skin after frying, crisp texture, and excellent quality. As a triploid variety, it is a new variety with high quality, early bearing, and strong stress resistance.