Growth responses of rooted cuttings from five clones of Picea abies (L.) Karst. after a short drought period

Water stress may be a problem during the establishment of a forest plantati on, and a drought may affect both root and shoot growth of newly planted se edlings. Rooted cuttings of five fast-growing clones of Norway spruce (Pice a abies (L.) Karst.] were studied in a well-watered environment and in an e nvironment with a 5-day drought period. The study was performed within an i ntermittent aeroponics system in a controlled environment chamber. During t he drought the root elongation was reduced to 1 mm day(-1) compared with 3 mm day(-1) in the well-watered treatment, but no significant reduction in s hoot elongation was registered. Seventeen days after rewatering, the root e longation of drought-treated plants had recovered completely. At the end of the study, the increase in root length for the measured period did not dif fer significantly between treatments, whereas the leading shoot length and biomass were greater in well-watered plants, The five clones, which had bee n selected for fast growth, reacted similarly to the drought treatment and no interaction between clone and drought was found. In conclusion. drought affected the root growth directly, whereas the shoot growth was indirectly affected. This may reduce future growth as a result of a smaller leaf area and thereby a less assimilate production.