Breeding report of a new litchi cultivar Linglong Litchi

Abstract: A novel late-maturing litchi variety called Linglong Litchi was chosen in Guangdong from an open-pollinated seedling (the tree is over 100 years old). It possesses a number of advantageous qualities, including a long maturation time, a high and steady yield, a bright red pericarp, excellent quality, high edibility and a high scorch rate. The tree was discovered in 2001 in Chigangshan village, Chigang town, Puning city. To assess their stability, we tracked the key economic variables, biological parameters, fruit quality and yield of the native cultivar from 2014 to 2019 for five consecutive years. Additionally, molecular markers confirmed its distinction from other litchi types. It was granted the name Linglong Litchi and received a certification from the Guangdong Crop Variety Approval Committee in November 2020. Linglong Litchi has a large and rounded crown as well as thick and rigid branches that radiate outward from the center. The tree is medium-sized, standing 2.59 to 2.82 meters in height on average. The panicle is 35.8 cm long and 18.5 cm wide, with 1200 flowers gathering together on average. The lanceolate leaves are 9.6-10.2 cm in length and 2.9-3.2 cm in width. The fruit is long heart-shaped, and the flesh is white, transparent, crispy and sweet with a brilliant scarlet pericarp. The maximum fruit weight is up to 27 g, while the average single fruit is 21.7 g. The brown seeds have a longitudinal diameter of 1.78-2.10 cm and a cross diameter of 1.10-1.62 cm. The fruit shape index is 0.9. The edible rateis 83.4%, while the abortion rate is 84.64%. The fruit has a hardness of 1.49 kg · cm^{- 2} , a soluble solids content of 19.3%, a total sugar content of 16.1%, a total acid content of 2.0 g·kg^-1 and 305.0 mg·kg^-1 of vitamin C. Compared to the Fengchuiliao Litchi, Linglong Litchi grows more vigorously, is more resistant to stress and disease, and may thrive in less favorable environmental circumstances. The average fruit cracking rate is 2.5%, which is comparable to the 2.7% of Huaizhi Litchi but significantly lower than 5.8% of Fengfengliao Litchi. After top- grafting, Linglong Litchi may be harvested in the third year, with an average yield of 639.8 kg · 666.7 m^-2 in the eastern and central parts of Guangdong province. The Puning region enjoys a lengthy harvest season that lasts from mid-June to mid-July. Huaizhi Litchi is often chosen as a rootstock for grafting in the spring or fall. Deep soil reclamation and digging of planting trenches must be done before planting. Trees should be spaced (4.0-6.0) m × (6.0-8.0) m apart in rows. A short cutting is required to encourage branching when young trees have a trunk diameter of 40-60 cm and the new shoots grow around 30 cm long. Additionally, adult trees require proper methods to manage winter sprouts. Flowers and fruits need to be thinned out adequately when the fruit set is excessive. Applying enough base fertilizer is suggested to guarantee proper output. Additionally, it is vital to prevent and control pests and diseases such as downy mildew, anthracnose, stem borers and litchi stink bugs. Due to the lengthy flowering and fruiting period, it is advised to supplement water-soluble fertilizer by foliar spraying after flowering to ensure normal growth of flowers and fruits.