Abstract:

Loblolly pine is the most widely planted southern pines for timber and pulp production in the southern United States. In China, loblolly pine was introduced more than 60 years. To identify the sources best suited for the diversity of climates and sites being planted in China, as well as to initiate tree improvement programs of genetically adapted plant material, provenance studies were started in 1981. This paper summarize the 15-year results at 6 locations of the 1981 trial. Seeds of loblolly pine was obtained from the Forest Tree Seed Center, USDA Forest Service, Macon, GA (Tab.1). They were of unimproved origin and were identified by state and county. Latitudes and longitude in the tables are for the centers of the counties; mean annual and rainfalls are from reporting stations closest to the county centers. Containerized seedlings were outplanted at about 5～8-month-old in six-tree row plots with 9 replications. Side-by side plantings of the 2 species were repeated 6 locations. Spacing was 3m×2m. One slash pine provenance (S-8, Tayor Co.FL) and a local lot of the indigenous Masson pine(P.massoniana) were included with each pine loblolly pine replication. In addition, one “land race” loblolly pine source(L-11,Minhou, Fujian) was included with each loblolly pine replication. 　Results of the provenance test showed that there were significant variation between different seed sources of loblolly pine. There were significant correlation between the height growth and the minimum temperature of the seed origin.The seed source by location interaction of the 11 provenances planted at 7 locations for loblolly pine was highly significant for height and diameter. Even though the interaction term was highly significant for height and diameter, 98% of the variation in the performance for loblolly pine was accounted for by location, 1.2% of seed source and seed source×location only 0.5%. This leaves very little of the variation (height) to be accounted for by the interaction and error terms. It means common best loblolly pine seed sources could be chosen.Coastal plains of loblolly pine seed sources grow fast, widely adapted could be used in our vast subtropical regions. In northern subtropical region and southern warm temperate region, western seed sources(Arkansas) and inland seed sources could be used, because southern seed sources are not cold resistant.Species comparison showed that in our southern subtropical, including low hills and coast sand soil, slash pine could be planted. In central subtropical region, both loblolly and slash pine could be planted. In northern subtropical region, loblolly pine could be planted, because loblolly pine grows faster and more resistant cold to than slash pine there.

Key words: Loblolly pine, Provenance test