土壤鹽度對繖楊苗木生長、水分狀態及葉綠素濃度之影響

Effects of Soil Salinity on Growth, Water Status and Chlorophyll Concentration of Thespesia populnea Seedlings

本研究旨在探討0、0.75、1.5 及3.0 % NaCl 等不同土壤鹽度處理，對繖楊（Thespesia populnea）苗木形質生長、水分狀態及葉綠素濃度之影響。試驗結果顯示，不同鹽分濃度處理30、60、90 及120 天後，苗高、地際直徑、乾物量及葉部參數均隨鹽度增加而降低。鹽分處理120 天後，以0.75 % NaCl 處理之苗高、地際直徑、葉片數、總葉面積、葉片大小、葉片伸展速率及各部位乾物累積量最大，顯示此為最適合繖楊苗木生長之鹽分濃度。以3.0 % NaCl 高鹽度處理之苗木，所有形態參數則明顯下降。苗木之葉片肉質程度會隨鹽度增加而增加，在處理120 天後，3.0 % NaCl 處理有最大肉質程度。苗木相對生長速率（RGR）、葉面積比（LAR）及葉重比（LWR）皆隨鹽度增加而降低，但淨同化速率（NAR）和比葉面積（SLA）並未受鹽度之影響。各處理之葉部含水率大致維持在76~80 % 間，各處理苗木無明顯的差異。處理120 天後，3.0 % 處理苗木之莖、根部含水率及成熟葉之相對含水率（RWC）明顯降低。而鹽分濃度並未影響各處理苗木葉片之葉綠素濃度。 The purpose of this study was to investigate the effect of soil salinity containing 0, 0.75, 1.5 and 3.0% NaCl on growth, water status and chlorophyll concentration of Thespesia populnea seedlings. The results indicated overall the morphological parameters of seedlings were decreased with increasing salinity. Seedling height, diameter at root collar, leaf numbers, leaf size, total leaf area, leaf expansion rate and dry matter accumulation of seedlings that cultivated in 0.75% NaCl were the most greatly enhanced after 120 days of treatment. This implied that the 0.75% NaCl was the optimum salinity for seedling growth of this species. All parameters of seedlings that cultivated in 3.0% NaCl were significantly suppressed. Succulence in leaves of seedlings was high when grown in increasing salinity and the highest degree of succulence was obtained at 3.0% NaCl treatments. Salinity significantly reduced relative growth rate (RGR), leaf area ratio (LAR) and leaf weight ratio (LWR), but net assimilation rate (NAR) and specific leaf area (SLA) were unaffected. Salinity level showed less effect on the leaf water content, which maintain at 76-80% in different salinity. However, seedlings grown in 3.0% NaCl significantly reduced the stem, root water content and the relative water content (RWC) of the fully expanded leaves. Salinity did not affect the total amount of chlorophylls in leaves.

The purpose of this study was to investigate the effect of soil salinity containing 0, 0.75, 1.5 and 3.0% NaCl on growth, water status and chlorophyll concentration of Thespesia populnea seedlings. The results indicated overall the morphological parameters of seedlings were decreased with increasing salinity. Seedling height, diameter at root collar, leaf numbers, leaf size, total leaf area, leaf expansion rate and dry matter accumulation of seedlings that cultivated in 0.75% NaCl were the most greatly enhanced after 120 days of treatment. This implied that the 0.75% NaCl was the optimum salinity for seedling growth of this species. All parameters of seedlings that cultivated in 3.0% NaCl were significantly suppressed. Succulence in leaves of seedlings was high when grown in increasing salinity and the highest degree of succulence was obtained at 3.0% NaCl treatments. Salinity significantly reduced relative growth rate (RGR), leaf area ratio (LAR) and leaf weight ratio (LWR), but net assimilation rate (NAR) and specific leaf area (SLA) were unaffected. Salinity level showed less effect on the leaf water content, which maintain at 76-80% in different salinity. However, seedlings grown in 3.0% NaCl significantly reduced the stem, root water content and the relative water content (RWC) of the fully expanded leaves. Salinity did not affect the total amount of chlorophylls in leaves.