Breeding report of a new chestnut cultivar Taishan 1 with high and stable yield

Abstract: Taishan 1 is a new chestnut cultivar with high and stable yield. Its parents come from farm varieties in Chuxian county, Anhui province, P. R. of China. It belongs to the Niandiban strain. It was first introduced by Zhao Yongxiao to Xintai city, Shandong province. A bud variety was selected from the Niandiban strain and approved in 2000. It was introduced to Baoji city, Shaanxi province in 2001, and then the multi- point regional experiments were carried out in various counties and districts of Shaanxi province. In 2018, it was approved by Shaanxi Forest Cultivar Approval Committee and still named Taishan 1. The tree crown is open, mostly in a center-open shape. The bark is taupe with dense lenticels. The leaf color is dark green, and the petiole is stout. The mixed bud is medium and large-sized. The mixed inflorescence is oblique bearing at the apex of the fruiting branch. The chestnut hull is large with the bur thorn being long, hard and forked. The number of nuts per bud is 2.8. The nuts are full and uniform in size, and the average weight of nuts is 18.0 g. Nuts are reddish brown with bright luster, few hairs and obvious tendons. The kernel is yellow, fine-waxy and sweet. The tegmen is easy to peel. The soluble sugar content is 12.8%, the starch content is 64.8%, the crude protein content is 4.7%, and the crude fat content is 0.9%. This cultivar has high and stable yield and strong fruiting ability year af-ter year. The current shoot in front of the fruit branch is long, there are many big buds, and it is easy to ini-tiate female flowers. The average number of involucres per plant is 254, but the empty rate is only 1%-2%. After grafting, it can bear nuts in the 2nd year, enter the high-yield period in 3-4 years, and the aver-age yield with 7-year-old trees is 7.6 kg. The average production capacity is more than 380 kg·666.7 m^-2.It is resistant to barren soil and has strong disease resistance. It is more resistant to storage and suitable for frying and processing. It is suitable for cultivation in the Qinling mountain area. The buds sprouted  at the end of March, the leaves expanded in early April, the tree entered full flowering period in early June, the fruit matured in early September, and the fruit development period lasted 100 days. It is suit-able for training natural center- open shape. During the full fruiting period, appropriate short cutting back and pruning should be carried out to promote the growth of nuts, timely retraction and renewal should be carried out to maintain the vigorous growth of trees, borax should be sprayed during the flow-ering period to improve the nut setting rate, and deep tillage or disc expansion should be carried out in winter to reduce the number of overwintering pests. After chestnut trees enter the old age period, the re-verse grafting method can be used for renovation and transformation, so as to adjust the tree structure and increase the number of inner nuts. This cultivar has been cultivated in a large area in Shaanxi chest-nut producing area.