Effect of fertilization, prunning and density on cutting quality and rooting ability of stem cuttings of Larix kaempferi (Lamb.)

Significant differences in rooting ability of Larix kaempferi (Lamb.) Carr. stem cuttings were observed as a result of Cultural conditions varied with stock plants. Data showed that the application of a specific amount of urea to ortets increased the rooting percentages of cuttings by 14% - 37% compared with control. In contrast, the nitrogen and phosphorus concentrations in the former cuttings decrease more than that in the latter during root formation. This changed process suggested the endogenous nutrient metablism stimulated by exogenous fertilizer. The cutting production from heavy hedged donor stocks was similar to that of unhedged ones, but those truncated and topped into the middle-sized cylindricality type give more expected cuttings both in quantity and in quality (length > 15 cm, basal diameter greater than or equal 0.3 cm), and special improvements were found at the middle and lower layers of the crown. For larch significant effect of prunning on new shoots development at the level of P = 0.01 occurred only in the first half of growth season, in the second half an orchard density became the dominant factor influencing good cutting forms which were relative to rooting potentials. As there was a strong correlation between crown layers of plants and the accumulated irradiance on them, a reasonable 1.5 h × 1.0 - 1.2 h space among seedlings in a hedged orchard is recommended according to the variance of shade length and bearing of ortets with motive orbit of the sun, when H represents the height of individuals.