A new early-ripening and low temperature resistant Chinese bayberry cultivar Zaoxian

Abstract: Zaoxian is a new early-ripening Chinese bayberry cultivar bred from an excellent variant individual plant found in the planting area of Zaose. The fruit is spherical, without a pedunculated convex ring. The fruit is dark red when fully ripe, and the flesh column is round and blunt. The average fruit weight is 13.99 g and can reach up to16.06 g. Flesh recovery is 91.17% . Soluble solid content is 12.54%, and total sugar content 8.46%. Titratable acid content is 1.09%; citric acid content 1.05%, and vitamin C content 59.88 mg · 100 g^-1 . Therefore, the fruit of Zaoxian are sweet and sour, with a unique umami taste and high quality. The tree vigor is weak with few and sparse branches, and therefore the canopy has good ventilation and light transmission. The leaves are dark green, narrowly obvate, obtuse at the apex, with an entire leaf margin. Medium and short fruit branches dominate the fruit tree, thus the number of fruit on the branches is relatively uniform. The stalk and the pulp are easy to separate after maturity, and the cultivar is early bearing and has no alternative bearing phenomenon. Generally, it enters the peak production period 6-8 years after top grafting. It is productive with an average yield of 800 kg·666.7 m^-2 . In Xiaoshan district, Hangzhou, Zhejiang, Zaoxian fruit matures in early June 6, about 5- 7 days earlier than Zaose. The cultivar has low-temperature tolerance. Under low-temperature stress, the soluble sugar content in the shoots increased by 32.1%, and the relative electric conductivity decreased by 12.5%. Therefore, Zaoxian is suitable for cultivation in northern Zhejiang and enables the northward expanding of bayberry planting area. Molecular identification using 99 gSSR and MrESTSSR markers showed that there were differences between Zaoxian and other 13 main cultivars of Chinese bayberry, and the relationship coefficient with Zaose was the largest, which was 0.92, proving Za-oxian a new variety. And Primer zaas 053 can distinguish Zaoxian from the other 12 varieties. It is suitable for cultivation in the south of the Yangtze River and areas with similar climate. It should be planted on acid red soil or yellow soil rich in gravel, and sod culture should be used for orchard soil management. Seedlings are mainly obtained via grafting propagation, and the scions are collected from the flowering branches of Zaoxian. From March to April every year, 1 to 2 year old rootstock seedlings with a stock diameter of 0.8-1.0 cm are selected for grafting. The grafted seedlings should be shaded in time after transplanting to prevent desiccation. The recommended spacing of planting is 5 m × 5 m or 5 m × 6 m. The spring shoot is the main fruit bearing branch of this variety. As the branches and shoots of the tree are sparsely distributed, there is no need for much manual pruning, flower thinning and fruit thinning in production. Some bare branches should be bent, and weak branches, overlapping branches and diseased shall be thinned out. In the first three years after planting, planting hole expansion and deep application of fertilizer is adopted. The top dressing is carried out 4 times in the first half of each year, and about 0.1 kg of compound fertilizer is applied to each plant each time. In the fruiting period, 1-2 kg of pure potassium sulfate fertilizer is applied three times in spring, summer and autumn to each plant each time, and the ratio of nitrogen, phosphorus and potassium for adult trees is 1∶0.3∶4. Bioorganic fertilizer is mainly applied in autumn and winter, with 15-25 kg per plant each time. It is necessary to strengthen routine cultivation management, maintain reasonable ventilation and light transmission of tree crown, and pay attention to clearing the orchard in winter. There are few diseases and insect pests. In winter, the branches and stems shall be painted Lime- Sulphur- Synthetic- Solution in time,to prevent the freezing damage and the snow shall be shaken off from thee tree crown in time after snow to prevent branch crush.