Effect of Shading on Leaf Longevity of 18 Hedge Plants

This study used leaf longevity as indicator to test shading tolerance of 18 hedge plants by an shading experiment, which included non-shading, 30% shading, 50% shading, 80% shading and 90% shading. Not only plant species but also shading rate had significant influence to average leaf longevity. In most of plants, leaf-longevity was significantly quadric correlated to shading rate. After change leaf-longevity to variation-of-leaf-longevity and arrange them by the order of variation-of-leaf-longevity, we found that the responses of shading on leaf-longevity could significantly show the shading tolerance of the plants. According to the order of variation-of-leaf-longevity and correlation between leaf-longevity and shading rate, the plants could divide into five groups. Group I. Non-shading tolerance, included Neolitsea parvigemma, Ilex triflora var. Kanehirai, Fraxinus formosana, Bougainvillea spp. and Aglaia formosana. Group II. High shading tolerance, included Murraya paniculata, Ardisia squamulosa, Distylium racemosum and Diospyros kotoensis. Group III. Slight shading tolerance, included Pittosporum pentandrum, Lantana camara and Ilex rotunda. Group IV. Middle shading tolerance, included Pyracantha koidzumii, Taxus sumatrana and Ardisia elliptica. Group V. Non response, included Gelonium aequoreum, Scolopia oldhamii and Diospyros vaccinioides.