In: Phyton 54, Fasc. 1 (2014): S.149-160 with 8 figures DOI: 10.12905/0380.phytons54(1)2014-0149

Key words: Koelreuteria bipinnata Franch., cambium, xylem , cell differentiation, development.

Summary

Liu R. R., Xu Y. M., Zhang J. Y. & Zhang L. H. 2014. Seasonal changes of cambium activity in Koelreuteria bipinnata Franch. in the subtropic zone of China. – Phyton (Horn, Austria) 54 (1): 149–160, with 8 figures.

Cambium activity is a source of timber production. During the growing season 2011, six trees of Koelreuteria bipinnata (Sepindaceae) were continuously monitored on the campuse of Huazhong Agricultural University in central China (located on 113°41’ to 115°05’ E and 29°58’ to 31°22’ N). From March 4, 2011 to February 24, 2012. Small stems of 15~20 cm length were sampled in the middle of 2~3 years old healthy, branches in the central crown of these trees. Cambial activity began at the end of February. In early March, cambium cells significantly increased in size with their walls gradually thinning. Cambium cell zone reached a maximum of 5–7 cell layers in June. That was maintained from May to July, and gradually decreased to 2~3 layers of thick-walled cells. Cambium entered dormancy period at end of October. Beginning of March the cambium began to form the first earlywood xylem vessels. Entire earlywood was completed in approximately 2 months (until mid-May). Entire latewood was completed in approximately 4 months (until mid-October). The final lignification of xylem was completed between mid-November to mid-December. Xylem differentiating into vessels, fiber cells and axial parenchyma cells occurred mainly from April to July. The width of xylem increased intensives from mid-June to mid-September while the phloem did from mid-April to mid-June. Stem volume increment basically stopped at the end of October.