Branch growth of Pinus elliottii in the hilly red-soil area of the mid-subtropical climatic zone

Key words: 
• botany /
• Pinus elliottii(mash pine) /
• internode length /
• basal diameter /
• meteorological factors /
• whorls

Abstract: From a review of the Pinus elliottii(mash pine)domestic and overseas literature on branching, the branch growth at the whorls was analyzed at the Qianyanzhou Experimental Station of the Chinese Academy of Sciences in Taihe County, Jiangxi Province, China and its relationship with several meteorological factors was determined. Branch growth for internode length(IL)and basal diameter(BD)was determine by vernier caliper,and their partial correlations with respect to the whorls were calculated. Additionally, the response to these meteorological factors during the growing periods was described in a multiple linear regression model. Results showed that branch ILgrowth for a givenyeardeclined from the upperwhorls to the lowerwhorls.Also,branch BD increased gradually from the upper whorls to the lower whorls, but slightly declined near the base of the crown.Distribution of the annual total branch volume waswell fitted to skewed leftnormal distribution curves.This showed that large brancheswere mainly concentrated in the middle-lower part of crowns.The linear regression accuracy for branch volume versus(BD2 branch length)was not very strong(r2= 0.45). However, the adjusted R2 of the multiple linear regression equations for ILand BDwith several meteorological factorswere all highly significant(0.96)(P 0.01), and the partial correlations were all highly significant(P 0.01). The partial correlations showed thatILgrowthmainly depended on canopy relative humidity.Also,BDgrowthwas negatively correlatedwith a cumulative temperature of 10℃ , while it was positively correlated with total precipitation.[Ch, 6 fig. 41ref.]