Performance and quality of Cupressus sempervirens L. mini-plug seedlings under reduced photoperiod

Abstract

Short-day treatment has been used for some conifer species to improve planting stock quality. The aim of this paper was to study the effect of short-day treatment on performance and quality of young seedlings of Italian cypress (Cupressus sempervirens L.), a conifer species abundant in the Mediterranean area. Seeds of Italian cypress were sown in mini-plug cavities. After 5 weeks of growth, seedlings were subjected to four different photoperiods: (a) 14 h (control), (b) 8 h, (c) 6 h, and (d) 4 h for a period of 1–3 weeks, before they were transplanted to bigger size containers. Reducing photoperiod did not result in bud formation or shoot inhibition although it increased the number of lateral shoots. Seedlings subjected to 6-h photoperiod for 2 weeks during pre-cultivation in mini-plugs had improved root characteristics, giving them a higher potential for outplanting success, especially in Mediterranean areas.