Early Growth Response of Super ior Provenance ofMa sson Pine to D ifferent Planting Den sities

A p rovenance-by-p lanting density-interaction trial ofmasson p ine at age nine on mid2fertility field inWuping of Fujian was used to investigate growth response pattern of five superior p rovenances to initial p lanting density.Results showed that the growth response to p lanting density varied largelywith p rovenances tested. Chongyi of J iangxi andWup ing of Fujian were the p rovenances with higher sensitivity to p lanting density, while Cenxi of Guangxiand Gaozhou of Guangdong were the p rovenanceswith less sensitivity to p lanting density, and the growth sensitivityof Xinyi of Guangdong to p lanting densitywas found to be moderate. Analysis indicated that three south p rovenancesincluding Cenxi of Guangxi, Gaozhou and Xinyi of Guangdong were suitable for short rotation management underhigh p lanting density of 1. 5 m ×2. 0 m with high growth increment of height, DBH and timber volume per area, andwere also fit for low p lanting density of 2. 0 m ×2. 5 m to cultivate big-diameter timber. Both p rovenances ofChongyi of J iangxi andWup ing of Fujian exhibited well atmoderate p lanting density of 2. 0 m ×2. 0 m. Growth dif2ferentiation among p rovenanceswas found to be related to initial p lanting density and to be great under high or lowp lanting density. Early selection of p rovenances seemed to have great efficiency under higher p lanting density. Itwasalso showed that p rovenance ×density interaction and block ×p rovenance ×density interaction were remarkable,thus different p lanting densitieswere needed according to different soils and different p rovenances for op timizing thelayout of superior p rovenances and p lanting density.