Influence of soil fertilization, plant spacing, and coppicing on growth, stomatal conductance, abscisic acid, and camptothecin levels in Camptotheca acuminata seedlings

Changes in amount of the plant alkaloid, camptothecin (CPT), were investiga ted in field-grown Camptotheca acuminata seedlings in response to fertiliza tion, variation in plant density, and coppicing, The relationship between C PT and growth, and abscisic acid (ABA) levels were also examined, Fertiliza tion caused positive responses in growth of both the slow- and the fast-gro wing C, acuminata plants. It lowered stomatal conductance (g), reduced leaf CPT level in slow-growing but not fast-growing seedlings in mid-summer (Ju ly), and increased leaf ABA level in dense plantings in early fall (Septemb er), Shoots induced to develop as a result of coppicing were significantly higher in leaf CPT level than the original non-coppiced shoots. These resul ts suggest that in the C, acuminata plantation management, coppicing should be employed to produce high concentrations of CPT, but that soil fertiliza tion should be used cautiously so that greater growth is not achieved at th e cost of lower CPT biosynthesis.