| Summary: | 碩士 === 國立臺灣大學 === 園藝學研究所 === 91 === To investigate the shade tolerance index, this study compared the leaf morphological and physiological characteristics of different shade tolerant plants under different natural environments and different levels of shading situation.
Under natural environments, 20 common ornamental plants in Taiwan such as Ternstroemia gymnanthera, Camellia japonica, Schefflera arboricola, Murraya paniculata, Palaquium formosanum, Cerbera manghas, Osmanthus fragrans, Pongamia pinnata, Melaleuca leucadendra, Artocarpus altilis, Albizzia lebbeck, Bauhinia variegate, Erythrina corallodendron, Plumeria ruba var. acutifolia, Lagerstroemia indica, Koelreuteria formosan var. nakaharai, Prunus campanulata, Pistacia chinensis, Cassia surattensis and Bougainvillea spectabilis were used to observe the leaf morphological and physiological characteristics. According to the different review about ornamentals, those plants were grouped and given the shading index. The correlation between shading index and the data of observation were tested. The results showed that there were positive correlation between shading index and specific leaf weight(SLFW) ( r=0.8016*** ), tempetature difference between leaves and air(△T)(r=0.7825***), leaf thickness(r=0.7776***), chlorophyll meter reading values(CMR) ( r=0.6720** ), chlorophyll a content( r=0.5436* ) and chlorophyll a+b content( r=0.4926* )。
According to the light compensation point (LCP), ten common ornamental plants were classified into two groups: Shade tolerant plants( LCP under 25mmole/m2s) such as Aglanonema modestum, Camellia japonica, Ternstroemia gymnanthera and Schefflera arboricola; shade intolerant plants ( LCP over 26mmole/m2s) such as Bougainvillea spectabilis, Prunus campanulata, Cassia surattensis, Lagerstroemia indica, Duranta repens and Bauhinia variegate. Two months after placed those plants under 0%, 30% and 85% shading environments, leaves morphological and physiological characteristics were recorded. The results showed that the chlorophyll fluorescence(CF), CMR, chlorophyll a content, chlorophyll b content and chlorophyll a+b content of shade tolerant plants increased obviously when light level decreased. On the contrary, in shade intorerant plants, the leaf water content increased obviously, whereas LCP, SLFW, SLW, leaf thickness and CMR decreased significantly.
To obtain the shade tolerance index, the LCP under 0% shading level of plant species, Aglanonema modestum, Camellia japonica, Ternstroemia gymnanthera, Schefflera arboricola, Bougainvillea spectabilisthe, Prunus campanulata, Cassia surattensis, Lagerstroemia indica, Duranta repens, Bauhinia variegate, were measured. The correlation between LCP and values of leaves morphological and physiological characteristics obtained from 0%, 30% and 85% shade were analyzed. The results showed that the most significant correlation exised between LCP and △T under 0% shading environment(r=-0.9746***). The correlation exised stronger within chlorophyll a content(r=-0.7896**) than in CMR values(r=-0.7823**) under 85% shading environment. The correlation between LCP and the ratio of the values of leaves morphological and physiological characteristics obtained from different shading environments (85%/0%, 30%/0%, and 85%/30%) were analyzed. The most significant correlation existed between LCP and ratio of chlorophyll a content (30%/0%, r=-0.8566**). The consequent items are followed as in ratio of chlorophtyll a+b content (30%/0%, r=-0.8529**), ratio of SLW(85%/0%, r=-0.8493**), ratio of CMR value(30%/0%, r=-0.8456**) and ratio of leaf thickness(85%/0%, r=-0.8071**).
To conclusion, when considering the convenience, △T under no shading environments, CMR and SLFW under shading environments, or ratio of SLFW, leaf thickness and CMR values under two different shading levels might be a shade tolerance index to select shade tolerant plants.
|
|---|
