A replantation disease resistant new peach rootstock cultivar Zhong Tao Kang Zhen No. 1

Abstract: Due to the short economic life of peach trees, most peach orchards require annual renewal. Thus, we need to overcome the obstacles of peach tree replanting disease. At the same time, we also lack of asexual resistant rootstocks for standardized orchard establishment in the peach industry. We started the breeding program of multi- resistance rootstock since the 1980s. Through multi- generation hybridizations, a replantation disease and Meloidogyne incognita resistant rootstock was released. Zhong Tao Kang Zhen No. 1 is a multi- resistance rootstock cultivar, selected from the population between 96-7-6 and Hong Gen Gan Su Tao 1 that were crossed in 1999. The female parent 96-7-6 comes from the population Beijing 2-7× Le Yuan crossed in 1996, and Hong Gen Gan Su Tao 1 was selected from wild resources of Prunus kansuensis in 1981. The female parent Beijing 2-7 were selected from the seedlings of the cross population of Hakuho× Hong Shou Xing. The Zhong Tao Kang Zhen No. 1 has 34.23% long bearing branches, 27.93% medium bearing branches, 30.63% short bearing branches, 0.90% bouquet bearing branches, and 6.31% apprentice bearing branches; annual flowering branches have medium anthocyanin color development, 6.07 mm flowering branch thickness, 60.5 flower buds per m, and 2.20 cm internode length. The chilling requirement is about 400 h. In Zhengzhou, flowering starts around 12 March, with an early flowering period that lasts 10 days. The flowers are showy, with orange- red anthers and lots of pollen, and are self-compatibility. The fruit matures at mid to late July and the shape is round with little color, acidic flavor and free stone. Zhong Tao Kang Zhen No. 1 has good grafting compatibility with various peach varieties, high root resistance to replanting disorders and southern root knot nematodes, and is drought and infertile tolerant. It has strong resistance to replanting obstacles in both sandy and clayey heavy crops and is characterized by fast growth, vigorous growth,non-yellowing leaves and a well-developed root system, with no significant effects on fruit, shape appearance and flavor. From 2010 to 2016, Zhong Tao Kang Zhen No. 1 was used as rootstock to graft Zhong Nong Jin Hui, Zhong You Jin Ming, Zhong Pan 11, Zhong You Pan 7 and Zhong Tao Jin Kui. The grafted parts are smooth, with good affinity. And 2019 to 2020, Zhong Tao Kang Zhen No. 1 was used to graft more than 900 germplasm (including peach, plum and apricot) preserved in the National fruit germplasm repository in Zhengzhou, all of which showed good grafting compatibility and smooth healing at the grafting site. In the spring of 2010, Zhong Nong Jin Hui was grafted by rootstocks of Zhong Tao Kang Zhen No. 1, Xinjiang Mao Tao and GF677. In the second year after planting, Zhong Tao Kang Zhen No.1 was able to bear fruit, and in the third year it was productive, with a yield of 1760 kg per 666.7 square meters, while Xinjiang Mao Tao rootstock only have a maximum yield of 830 kg per 666.7 square meters in the third year. Zhong Tao Kang Zhen No. 1 and seedlings of Xinjiang Mao Tao rootstocks were used to identify resistance to nematodes for two consecutive years in 2019 and 2020. The results show that Zhong Tao Kang Zhen No. 1 was not damaged by nematodes. Zhong Tao Kang Zhen No. 1 is an interspecific hybrid needs to be propagated asexually by cuttings and tissue culture. The results of comparative rootstocks and regional trials show that Zhong Tao Kang Zhen No. 1 is a rootstock that is resistant to both peach replanting disease. It has good grafting compatibility with various peach varieties and can be used for replanting old peach orchards. However, attention should be paid to controlling the vigorous growth of grafted cultivars to achieve early and abundant yield.