Báo cáo lâm nghiệp: Water relation characteristics and photosynthesis of saline-stressed seedlings of non-halophyte species

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Water relation characteristics and photosynthesis of saline-stressed seedlings of non-halophyte species...
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Báo cáo lâm nghiệp: "Water relation characteristics and photosynthesis of saline-stressed seedlings of non-halophyte species"Water relation characteristics and photosynthesis ofsaline-stressed seedlings of non-halophyte speciesT. Suzaki H. Yahata H. ShigenagaLaboratory of Silviculture, Department of Forestry, Faculty of Agriculture, Kyushu University,Fukuoka, Japan artificial seawater) were imposed by daily irriga-Introduction tion of 100 ml for 40 d. Time-course changes in photosynthetic rates were determined using an open gas-exchange system with an infrared gasMost plants show growth retardation at analyzer. The conditions of measurement werelow salinity and die in high salinity. The that light intensity was 40 klx, leaf temperaturecauses are considered to be mainly water was 25°C, and the air flow rate was 1.2 I/min.stress and/or ion excess. Plants may be Pressure-volume curves were constructed at the termination of treatment. After treatment,able to cope with an adverse water rela- sodium, potassium and chloride concentrationstion, if they absorb salts in leaf cells to were determined for leaves, stem, main rootadjust osmotically. But, without efficient and fine roots. Sodium and potassium werecompartmentation in vacuoles or exclu- estimated by flame photometry. Chloride wassion of excessive salt in osmotic adjust- determined by silver ion titration.ment, which are recognized in halophytes,plants will suffer from ion excess. Theobjective of the present study was to ex-amine the distribution of salts and its effect Results photosynthesis for non-halophyteonwoody species. In addition, the contribu-tion of sodium and chloride to osmotic Time in photosynthetic changes courseadjustment is discussed. shown relative values rates were as against 0% treatment. Photosynthesis by O. asiaticus var. aurantiacus decreased progressively as the salinity level in-Materials and Methods creased and time lapsed (Fig. 1 a). In D. racemosum, the lower salinity treatmentsThe seedlings of each species, Osmanthus stimulated photosynthesis on d 10. Afterasiaticus var. aurantiacus, Distylium racemo- that, while declining substantially abovesum, Cinnamomum camphora and Euonymus 20% treatment, it remained high in 10%japonicus were established in 1/5000 a Wagner and 5% treatments (Fig. 1b). In C. cam-pots. Salt treatments (0, 5, 10, 20 and 40% there were no significant effects In D. racemosum and C. camphora, itphora, 2a).under 10% treatment but gradual de- decreased for lower salt treatments (Fig.creases above 20% (Fig. 1 c). E japo- 2b, c). These reductions were considerednicus showed some decreases for higher to be caused mainly by other solutes andsalt treatments, which were less compared not by sodium or chloride. At the higherto the other species (Fig. 1d). concentration, osmotic potential became higher than that of the calculated value. The extent of sodium accumulation in E. japonicus seemed to use sodium andleaves and fine roots showed marked dif- chloride for osmotic adjustment, while, inferences between O. asiaticus var. auran- this situation, the sodium and chloridetiacus and the other 3 species. In O. asia- concentration in leaves was low (Fig. 2d).ticus var. au ...