Breeding report of a new early-ripening variety of Chinese chestnut Zaoli 5

Zaoli 5 is a new early-ripening chestnut (Castanea Mollissima ) variety selected through occational seedling selection in Changping area which belongs to Yanshan Mount. The mother plant was 100 years old and found on the hillside in 2001 because of the characteristics of early maturity and high quality. The field trials were arranged from 2003 to 2013 using top-grafting trees on 4-5 years old seedlings, the evaluation growing and fruiting characters was carried out from 2016 to 2019 using the local main cultivar Yanshanzaofeng as control. The tree had a moderate posture and semi-straight branches. The annual branches with little hair were grayish green in color, the bark was taupe with deep longitudinal cracking and dense lenticels. The leaves were ellipse withserrate, spreading, and gradually acute apex. The mixed bur was ellipse, brown and medium large-sized. The average length of catkin was 8.1 cm and the numbers of catkin on each biennial bearing branch was 6.57. The length of current shoot in front of the fruit branch was 6.7 cm. The tree had many big buds with ease to form female flowers. The average weight of the bur was 55 g and the shape was ellipse, the density was intermediate. The average length of spine bundle was 1.3 cm. Each bur contained 2.1 nuts, with a seed yield of 46.25%. The nuts were reddish brown and glossy, the average weight of the nuts was 8.1 g. The stripes on the nut was not obvious, and tghe size of hilum was intermediate. The kernel was faint yellow in color, fine- textured and smoothy. The tegmen was easy to peel. The shoot in front of the fruit branch was long. The soluble sugar content was 21.37%, the starch content was 38.2%, the crude protein content was 4.7%, and the crude fat content was 1.0%. The buds sprouted at the mid of April, the leaves expanded in late April, the tree entered full flowering period in mid June. The nuts ripened in about August 25 in Beijing area, and the fruit development period was only 75 days, 7 days less than that of the check cultivar Yanshanza-ofen’with the same cultivation management. The trees could bear nuts in second year after top-grafting. It had strong resistance to diseases and was suitable for cultivation in the Yanshan mountain area.