Study on Seedling Growth Rhythm of Zenia insignis as Valuable FastGrowing Native Tree Species in Guangxi

A logistic equation was formulated to describe the height and basal diameter growth dynamics of the annual Zenia insignis seedlings from seed germination to the end of the first growing season. An area correlation analysis was done according to the closeness of the observed parameters to the dynamic curve on the gray system composed of the seedling growth increment and the meteorological factors including aerial temperature, relative humidity, rainfall and solar radiation hours that influence upon the seedling growth. The results showed that the seedling response fitted the logistic equation quite well, the annual growth increment displayed a distinct alternation of ‘slowfastslowfastslow’ rhythm. The yearly growth course of the seedlings might be partitioned into four periods of time by the sequential clustering analysis, i.e., the emergence stage, pregrowth stage, fastgrowing stage and the postgrowth stage. The gray correlation analysis revealed that air temperature had the most significant influence while relative humidity had the least impact on height growth of the seedlings. The number of hours of solar radiation had the greatest influence among the major meteorological factors on the diameter growth. Similarly, relative humidity did the least contribution to the diameter growth.