Effects of Partial Defoliation on the Growth of Liriodendron tulipifera L. Seedlings

Partial defoliation of Liriodendron tulipifera L. by removalof leaflets as they emerged from the protective buds affecteda variety of growth parameters. Reductions occurred in totaldry weight production, the percentage of new growth devotedto foliage, leaf area ratio, and the increment of leaf areaper unit of leaf weight increment. Increases occurred in unitleaf rate and the rate of production of new leaves. Weight ofleaves near the base of the seedlings was unaffected by treatmentbut leaves developing at the end of the growing season werelarger on defoliated plants. The net effect of removing one-thirdand two-thirds of the developing leaflets was to reduce totaldry weight production by 14 and 42 per cent respectively.