Study On Techniques For Establishing Liriodendron Seed Orchard

Seed orchard is the plantation where produces seeds with high genetic value, and is thought to be superior to clonal propagation due to its lower cost and. higher genetic diversity. Therefore, seed orchard is widely used in tree breeding and seeds production. On account of good adaptability and strong heterosis, hybrid Liriodendron is gradually applied in gardening and timber producing. The problem in short supply of high genetic quality seeds has become more and more serious, which leads to the urgency of the establishment of hybrid seed orchard. This paper first reported the establishment techniques on a Liriodendron hybrid seed orchard based on progeny test data which were accumulated by our group in recent years, combining with SSR genetic diversity information of mating parents. The suitable clone number in a Liriodendron hybrid seed orchard was determinated upon balancing genetic gain and genetic diversity. To select the parentage clones for a Liriodendron hybrid seed orchard, several indexes, such as breeding value (general combining ability,GCA), reproduction fitness and special combining ability (SCA) were considered throughoutly. Finally, a Liriodendron hybrid seed orchard was established under two types of clone arrangement. The main results were as follows:To ascertain the clone number for a Liriodendron hybrid seed orchard, the family average values of 34 half-sib progenies from 3 testing sites (Jingdezhen in Jiangxi, Jingxian in Anhui and Xiashu in Zhenjiang) were used to evaluate the genetic value for each mating parent. The best clone number was. determined by logistic curve fixing after analyzing the relationship between clone number, genetic gain and SSR genetic diversity.20 clones would be sutable for a tulip tree seed orchard upon blancing genetic gain and genetic diversity.Based on growth performance of 75 mating combinations in 3 testing sites, breeding value, general combining ability, special combining ability and heterosis of each parent were evaluated. The choice rule for parentage clones was as follows: clones suitable as female parents were first considered according to its breeding value (general combining ability). Female reproduction fitness was tht second, and special combining ability was the last While clones suitable as male parents were chosen by its breeding value (general combining ability) and special combining ability. Male reproduction fitness was the last factor considered. Afterall,24 clones were selected. Clones which are suitable to be female parents were Z, L, J and N2. Clones which are suitable to be male parents were L2, BK1, XN1, C4,C5, YY1, FY1, M,C1,C3, SZ, S1, W, S, C2, J1and SZ1.There were 4 rules for clone deployment in Liriodendron seed orchards: avoiding inbreeding, special combining ability, breeding values and female reproductive fitness of parents, considering thinning. Five clone deployment schemes were outlined, of which 2 schemes (plum-shaped, one line one clone) were actually used to establish a Liriodendron hybrid seed ochard, including 24 clones,10 blocks, spacing 4m×4m, total area 5 ha.