Báo cáo lâm nghiệp: Photosynthesis and leaf longevity in alder, birch and ash seedlings grown under different nitrogen

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Photosynthesis and leaf longevity in alder, birch and ash seedlings grown under different nitrogen...
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Báo cáo lâm nghiệp: "Photosynthesis and leaf longevity in alder, birch and ash seedlings grown under different nitrogen"Photosynthesis and leaf longevity in alder, birchand ash seedlings grown under different nitrogen levelsT. Koike 1 2 M. Sanada1 Swiss Federal Institute of Forestry Research, 8irmensdorf ZH, Swi!zerland, and2 Hokkaido Branch, Forestry and Forest Products Research Institute, Sapporo, JapanIntroduction Until the final supply, total amount of nitrogen in each pot was 5.0, 1.5, 1.0 and 0.35 g. Sup- plying date and the percentage against the total amount was July 1 40%; July 24 20%; Aug. 20With application of nitrogen fertilizers, 20%; and Sept. 15 20%, respectively.photosynthetic rates increase (Field and Gas exchange rates were determined by anMooney, 1986) and the leafy period is pro- open system with an infrared gas analyzerlonged (Linder and Rook, 1984). There is (URA2S, Shimadzu) in the summer of 1984. Air correlation between the maxi- negativea was stored in an airbag and was humified. The photosynthetic rate and its durationmum flow rate into the chamber (20 x 18 x 1.8 cm ) 3 was 66.7 cm Measurement conditions . 1 -s- 3(Koike, 1987). However, there is little infor- were regulated strictly with an artificially illumi-mation about the longevity of individual nated chamber (Koike, 1987). Leaf temperatureleaves after nitrogen treatments (Linder was kept at the optimum temperature of 20°Cand Rook, 1984). We report the relation- and was monitored by a copper-constantanship between photosynthetic rates and thermocouple. After gas exchange measure- ments, leaf area was determined by an arealeaf longevity of deciduous broad-leaved meter (AAM5, Hayashi). Dry weight of leavestree seedlings in relation to the anatomical was measured after drying at 85°C for 48 h.characteristics in leaves. Leaf chlorophyll was extracted with 80% ace- tone. Leaf nitrogen content was determined by a C-N corder (MT 500 W, Yanagimoto). Each measurement was replicated 3-5 times.Materials and MethodsOne yr old seedlings of alder (Alnus hirsuta ResultsTurcz.), birch (Betula maximowicziana Regel)and ash (Fraxinus mandshurica Rupr. var.japonica Maxim.) were planted in unglazed pots(diameter: 21 cm) filled with surface soil of the The photosynthetic rate at light saturationnursery including volcanic ash (Sanada, 1975). in each species was increased withAs nitrogen fertilizers, ammonium sulfate was increasing nitrogen content (Fig. 1). Withsupplied 4 times in each pot. Phosphate ammo-nium (0.2 g) was provided as basal dressing. increasing nitrogen levels, the dark respi- The chlorophyll content in leaves (Fig. 2). species increased with leaves of all increasing nitrogen, especially in birch. Small differences in the specific leaf alder and in birch were observed ...