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 tak en from glasshouse-grown stock plants of Cupressus sempervirens, C. torulos a, C. arizonica, and Chamaecyparis lawsoniana was examined. The response to fertilising of stock plants with macronutrients (NPK) or ma cronutrients plus microelements varied with species. Stock plant fertilisin g significantly reduced rooting rates in C. sempervirens cuttings, but sign ificantly 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 plan ts had no effect on rooting of cuttings. Treatment of stock plants with increasing concentrations of nitrogen fertil iser ((NH4)(2)SO4 in tap water) significantly affected rooting of most test ed species. Nitrogen treatments, however, had no significant effect on root ing of C. sempervirens and Chamaecyparis lawsoniana cuttings. In cuttings o f C. torulosa, C. arizonica and C. macrocarpa, however, the high nitrogen c oncentration (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 fr om stock plants of different C. sempervirens seed families. Shading of C. s empervirens stock plants significantly reduced rooting rates in certain fam ilies, but had no effect; in other families. Application of rooting powder (NAA-Captan mixture) to cuttings significantl y increased rooting rates, and in Chamaecyparis lawsoniana significantly in creased the number of roots per cutting, but had no effect on root length.