Growth Rhythm for Half-sib Families of Young Pinus kesiya Plantations in Southern Yunnan, China

Abstract:

In order to understand the relationship between monthly growth of Pinus kesiya and meteorological factors, the annual growth dynamic of 17 families were studied in southern Yunnan. The family plantation was established in June 2013, 17 half-sib families of P. kesiya introduced from Thailand and Vietnam were selected with P. kesiya var. langbianensis from local seed orchard as control, the diameter at breast height (DBH), height and timing of shooting were observed for a whole year since July 2015. Meanwhile, the effects of meteorological factors on growth rhythm and shooting law were also analyzed. The results showed that there were significant differences in DBH, height and shooting times among 17 families (P<0.05). These families could be divided into two types, family No. 7, 25, 61, 104 and 41 were fast-growth type (I), with annual mean increment of DBH and height for 2.03 cm and 1.46 m, respectively, and the others was slow-growth type (Ⅱ). The both types of P. kesiya families showed similar growth tendency, of the DBH growth had two peaks occurred in February and August, of and the height growth had three peaks in February to March, June, and August to October, and shooting had three peaks in May (spring shoot), August to September (summer shoot) and November (fall shoot), respectively. The shooting times of P. kesiya were one to four in a whole year, of which the number of families with twice shooting was the largest, accounting for 47% of the total trees, mainly in spring (72.78%) and summer (77.33%). The growth of P. kesiya was influenced mainly by monthly average temperature, and growth stagnation was short in January. So, it was recommended that tending management of P. kesiya young plantation should be conducted before two peaks of DBH and height growth, i.e. May to June and December to January, and pruning in January.

Key words:Pinus kesiya;Half-sib family;Shooting;Growth rhythm;Southern Yunnan