Analysis on Growth and Allometric Growth of Pinus yunnanensis Seedlings with Different Stem Types

PurposeTo compare the seedling growth difference, variation law and allometric growth of different stem types of Pinus yunnanensis, so as to lay a foundation for stand improvement of P. yunnanensis.

MethodsThe seeds of P. yunnanensis with straight and bend/twisted stems were collected from three populations of Yiliang, Xinping and Lufeng, respectively. The seedling height and ground line diameter of 9196 plants two-year-old P. yunnanensis seedlings from 140 families were measured and analyzed, and the growth variation and allometric growth among and within types were discussed.

ResultsThe coefficients of variation of seedling height and ground line diameter of straight stem type and bend/twisted stem type were 34.80%-42.92% and 34.29%-55.36%, respectively. The seedling height variation coefficient of P. yunnanensis bend/twisted stem type was higher than that of straight stem type. The difference of allometric growth index between the two stem types was different, and the variation of seedling height was more obvious than that of ground line diameter. There were extremely significant differences in allometric growth of seedling height and ground line diameter between the two stem types of the three populations (P<0.01). The allometric growth index of Xinping bend/twisted setm type and Lufeng straight stem type were in accordance with the geometry similarity, and they were isotropic growth. The other types were allometric growth, and did not conform to any of the three tree mechanical designs.

ConclusionTwo kinds of stem types seedlings of three populations had different degrees of variation in the same cultivation environment. In comparison, the variation of P. yunnanensis seedlings among populations was greater than that among types, the growth of the bend/twisted stem type is better than that of the straight stem type.