The effect of fertiliser and shading treatments on rooting efficiency in cuttings of the cupressaceae

The effects of different fertiliser applications on rooting of cuttings taken from glasshouse-grown stock plants of Cupressus sempervirens, C. torulosa, C. arizonica, and Chamaecyparis lawsoniana was examined.

The response to fertilising of stock plants with macronutrients (NPK) or macronutrients plus microelements varied with species. Stock plant fertilising significantly reduced rooting rates in C. sempervirens cuttings, but significantly increased rooting in C, torulosa, C. arizonica and C, macrocarpa cuttings treated with rooting powder, in comparison to control stock plants treated with tap water. Fertilising of Chamaecyparis lawsoniana stock plants had no effect on rooting of cuttings.

Treatment of stock plants with increasing concentrations of nitrogen fertiliser ((NH4)(2)SO4 in tap water) significantly affected rooting of most tested species. Nitrogen treatments, however, had no significant effect on rooting of C. sempervirens and Chamaecyparis lawsoniana cuttings. In cuttings of C. torulosa, C. arizonica and C. macrocarpa, however, the high nitrogen concentration (800 mg N.l(-1)) significantly reduced rooting rates, whereas the lowest nitrogen concentration (100 mg.l(-1)) induced maximum rooting.

Significant variability was found in rooting abilities of cuttings taken from stock plants of different C. sempervirens seed families. Shading of C. sempervirens stock plants significantly reduced rooting rates in certain families, but had no effect; in other families.

Application of rooting powder (NAA-Captan mixture) to cuttings significantly increased rooting rates, and in Chamaecyparis lawsoniana significantly increased the number of roots per cutting, but had no effect on root length.