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.本研究以叶片寿命为评价指标，通过设置无遮阴、30%遮阴、50%遮阴、80%遮阴及90%遮阴共5个梯度的遮阴试验，对18种绿篱植物的耐荫性开展评价。研究结果表明，植物种类与遮阴强度均对供试植物的平均叶片寿命存在显著影响；多数供试植物的叶片寿命与遮阴强度呈显著二次相关关系。将叶片寿命转换为叶片寿命变异率，并按各供试植物的叶片寿命变异率进行排序后，研究发现植物叶片寿命对遮阴的响应特征可直观反映其耐荫性强弱。基于叶片寿命变异率排序及叶片寿命与遮阴强度的相关关系，可将18种供试植物划分为5类： Ⅰ类 非遮阴耐受型：包含Neolitsea parvigemma、Ilex triflora var. Kanehirai、Fraxinus formosana、Bougainvillea spp.及Aglaia formosana。 Ⅱ类 高耐荫型：包含Murraya paniculata、Ardisia squamulosa、Distylium racemosum及Diospyros kotoensis。 Ⅲ类 弱耐荫型：包含Pittosporum pentandrum、Lantana camara及Ilex rotunda。 Ⅳ类 中耐荫型：包含Pyracantha koidzumii、Taxus sumatrana及Ardisia elliptica。 Ⅴ类 无响应型：包含Gelonium aequoreum、Scolopia oldhamii及Diospyros vaccinioides。