氮肥型態對欖李（Lumnitzera racemosa）苗木生長、葉綠素濃度及細胞活性之影響

Effects of Nitrogen Form on the Growth, Chlorophyll Concentration and Cell Viability of Lumnitzera racemosa Seedlings

本研究探討銨態氮（NH4（上標+）-N）及硝酸態氮（NO3（上標-）-N）不同比例（0／0、0／100、25／75、50／50、75／25及100／0）施肥處理30至120days後，對欖李（Lumnitzera racemosa）苗木生長、葉綠素濃度、細胞三苯基氯化四唑（Triphenyl tetrazolium chloride, TTC）還原性及生長介質pH之影響。結果顯示處理120days後，苗高、地際直徑、各部位乾物重、葉片數、總葉面積及苗木品質指數等，均以NH4（上標+）-N／NO3（上標-）-N混合比例為50／50處理者較施用單一氮源者為佳。葉面積比（LAR）及葉重比（LWR）大致以氮肥比例為25／75、50／50及75／25等處理較高，比葉面積（SLA）則以50／50處理者最高。至於苗木之葉綠素a、b及總葉綠素濃度以25／75、50／50、75／25及100／0等4種處理較高，未施肥者最低。苗木葉部及根部細胞TTC還原性均以比例為50／50處理者最高（分別為15.16及11.77O.D.g^(-1)）。N肥型態明顯影響水樣及介質pH值，係隨NO3（上標-）-N比例增加而升高，隨NH4（上標+）-N比例增加而下降。完全施用NO3（上標-）-N時，水樣及介質pH值分別升至7.3及7.6；完全施用NH4（上標+）-N時，水樣及介質pH值分別降至5.6及4.4。 The study examined the effects of varying level of NH4(superscript +)-N/NO3(superscript +)-N ratio (0/0, 0/100, 25/75, 50/50, 75/25 and 100/0) on the growth, chlorophyll concentration, cell triphenyl tetrazolium chloride (TTC) reduction, and medium pH of Lumnitzera racemosa seedlings from 30 to 120 days after treatment. The results indicated that 120 days after treatment, the height, diameter at root collar, dry weight of various components, number of leaves, total area of leaves, and Dickson Quality Index were the highest in NH4(superscript +)-N/NO3(superscript -)-N ratio being 50/50 than sole N forms. The leaf area ratio (LAR) and leaf weight ratio (LWR) were high of seedlings cultivated with NH4(superscript +)-N/NO3(superscript -)-N ratio being 25/75、50/50 and 75/25. Specific leaf area (SLA) was the highest in NH4(superscript +)-N/NO3(superscript -)-N ratio being 50/50. Concentrations of chlorophyll a and b, as well as the total amount of chlorophylls were high for seedlings fertilized with NH4(superscript +)-N/NO3(superscript -)-N ratio being 25/75、50/50、75/25 and 100/0, and was the lowest in 0/0 treatment. Seedlings grown at NH4(superscript +)-N/NO3(superscript -)-N ratio being 50/50 had the highest TTC reduction of leaf and root tissue (15.16 and 11.77 O.D.g^(-1), respectively). The pH value of cultural medium was affected markedly by nitrogen form, which was increased with increasing NO3 (superscript -)-N and decreased with increasing NH4(superscript +)-N nutrient solution. The water and medium pH values were up to 7.3 and 7.6 in the medium contained NO3(superscript -)-N alone, while they decreased to 5.6 and 4.4 with 100% NH4(superscript +)-N treatment.

The study examined the effects of varying level of NH4(superscript +)-N/NO3(superscript +)-N ratio (0/0, 0/100, 25/75, 50/50, 75/25 and 100/0) on the growth, chlorophyll concentration, cell triphenyl tetrazolium chloride (TTC) reduction, and medium pH of Lumnitzera racemosa seedlings from 30 to 120 days after treatment. The results indicated that 120 days after treatment, the height, diameter at root collar, dry weight of various components, number of leaves, total area of leaves, and Dickson Quality Index were the highest in NH4(superscript +)-N/NO3(superscript -)-N ratio being 50/50 than sole N forms. The leaf area ratio (LAR) and leaf weight ratio (LWR) were high of seedlings cultivated with NH4(superscript +)-N/NO3(superscript -)-N ratio being 25/75、50/50 and 75/25. Specific leaf area (SLA) was the highest in NH4(superscript +)-N/NO3(superscript -)-N ratio being 50/50. Concentrations of chlorophyll a and b, as well as the total amount of chlorophylls were high for seedlings fertilized with NH4(superscript +)-N/NO3(superscript -)-N ratio being 25/75、50/50、75/25 and 100/0, and was the lowest in 0/0 treatment. Seedlings grown at NH4(superscript +)-N/NO3(superscript -)-N ratio being 50/50 had the highest TTC reduction of leaf and root tissue (15.16 and 11.77 O.D.g^(-1), respectively). The pH value of cultural medium was affected markedly by nitrogen form, which was increased with increasing NO3 (superscript -)-N and decreased with increasing NH4(superscript +)-N nutrient solution. The water and medium pH values were up to 7.3 and 7.6 in the medium contained NO3(superscript -)-N alone, while they decreased to 5.6 and 4.4 with 100% NH4(superscript +)-N treatment.