Comparisons of Leaf Position in Reaching Maximum Photosynthetic Capacity for Tree Species with Various Tolerance Statuses

• Main Authors: Yan, Chun-Ching, 顏君靜
• Other Authors: Kuo, Yau-Lun
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/68771247448358242979

碩士 === 國立屏東科技大學 === 森林系所 === 101 === Photosynthesis is an important physiological activity for a plant. Researchers usually choose morphologically mature leaves when measuring the plant’s photosynthesis. However, different species varies at the times of morphological maturity and physiological maturity. The objective of this study was to compare the leaf positions in reaching maximum photosynthetic capacity (Amax) for tree species with various shade-tolerant statuses, including pioneer, moderate shade-tolerant and shade-tolerant species. This study investigated 7 pioneer species, (i.e. Hibiscus taiwanensis, Trema orientalis, Mallotus japonicus, Terminalia catappa, Salix warburgii, Bischofia javanica, and Ficus septica), 4 moderate shade-tolerant species, (i.e. Machilus zuihoensis, Margaritaria indica, Michelia compressa, and Heritiera littoralis), and 8 shade-tolerant species (i.e. Gelonium aequoreum, Diospyros philippensis, D. maritima, Gonocaryum calleryanum, Myristica ceylanica var. cagayanensis, Beilschmiedia erythrophloia, Calophyllum blancoi, and Drypetes littoralis). The experiment was conducted with two methods. First, a continuous monitoring method was employed to monitor the dynamics of photosynthesis from a leaf’s initial expanding to maturity as Amax is reached and then reduced to 80% in Fic. septica, Mar. indica, and Her. littoralis. The second method (non-continuous monitoring method) measured the photosynthetic capacity of leaves at different positions along a same branch in 19 species. The results from these two methods were compared, and suitable species for each method were recommended. Results of the continuous monitoring method showed that, for Fic. septica, Mar. indica, and Her. Littoralis, Amax was reached at 28 d, 21 d, and 91 d, respectively, and the leaf position at which Amax was reached was at the 5th, 5th, and 9th, respectively. Optimum physiological activites were detected in leaf positions of 4th~7th, 4th~9th, and 6th~12th for Fic. septica, Mar. indica, and Her. Littoralis, respectively. Results of the non-continuous monitoring method showed that the leaf position at which Amax was reached in the 7 pioneer species could be classified into three types. The first type was at the 3rd position, including Fic. septica, Ter. catappa, and Tre. orientalis; the second type was at the 7th position, including Hib. taiwanensis and Mal. japonicus; the third type was between the 13th and the 17th position, including Bis. javanica and Sal. warburgii. All four moderate shade-tolerant species (i.e. Mac. zuihhoensis, Mar. indica, Mic. compressa, and Her. littoralis) reached Amax at the 7th leaf position. The leaf position at which Amax was reached in the 8 shade-tolerant species could also be classified into three types. The first type was at the 3rd position, including Bei. erythrophloia and Gel. aequoreum; the second type was between the 5thand the 7th position, including Myr. ceylanica var. cagayanensis, Dio. maritima, Dry. littoralis, Gon. calleryanum, and Cal. blancoi; the third type was between the 10th and the 12th position, and only Dio. philippensis belonged to this type. Comparing the leaf positions for reaching Amax by the two methods, no significant differences were found in Fic. septica and Her. Littoralis; however, significant difference was found in Mar. indica. In addition, the species with shorter intervals for generating new leaves, Amax would be reached at the leaf of latter position. Moreover, species with larger leaf mass per area had longer intervals for generating new leaves. In conclusion, leaf positions at which Amax was reached varied with different species. This position was at the 7th leaf position for moderate shade-tolerant species, while it was not consistent for pioneer and shade-tolerant species.