Selection of superior hybrid larch families and growth rhythm analysis

Taking 10-year-old hybrid larch test plantation in Linkou County of Heilongjiang Province as the research object, we surveyed and analyzed the growth traits of larch. The variation analysis showed that there were great variations in growth traits. In term of the height, the mean of four families (Larix kaempferi 5 × L. gmelini 12, L. kaempferi 3 × L. gmelini 2, L. kaempferi 12 × L. gmelini 9, L. kaempferi 3 × L. gmelini 9) was 26.09% higher than that of total families, 104% higher than CK, 37.88% higher than Baidaoshan provenance, 16.23% higher than Xiaobeihu provenances (L. olgensis), and 42.02% higher than Wuyiling provenance (L. gmelini). In term of the DBH, the mean of four families (L. kaempferi 5 × L. gmelini 12, L. kaempferi 3 × L. gmelini 2, L. kaempferi 12 × L. gmelini 9, L. gmelini 6 × L. olgensis 6) was 24.94% higher than that of total families, and 20.39% higher than CK. The analysis of variance showed that differences between families were significant. Analysis of ratio of biomass in each part showed that the L. kaempferi 5 × L. gmelini 9 and L. kaempferi 11 × L. gmelini 2 had more trunk biomass, but foliage biomass was lower than other families. Combining the results of multiple comparison and ecological adaptation index analysis, we considered L. kaempferi 5 × L. gmelini 9 and L. kaempferi 11 × L. gmelini 2 as the superior families. In term of height, L. kaempferi 5 × L. gmelini 9 was 24.91% higher than L. kaempferi 5 × L. gmelini 12, 12.23% higher than the mean of total families, and 2.87% higher than CK. In term of DBH, L. kaempferi 5 × L. gmelini 9 was 40.68% higher than L. kaempferi 5 × L. gmelini 12, 21.51% higher than the mean of total families, and 8.50% higher than CK. The analysis of growth rhythm showed that, compared with other families, superior families had a longer growing period, and had a higher growth rate than other families during the rapid growing period of larch.