氮素营养对白檀幼苗生长及光合特性的影响

Effects of Nitrogen Nutrition on Seedling Growth and Photosynthetic Characteristics of Symplocos tanakana

为确定适合白檀幼苗快速生长的最佳施氮量和提高白檀幼苗培育效率,以1年生白檀幼苗为试验材料,设置CK(0 g·株^(-1))、N1(4.5 g·株^(-1))、N2(7.5 g·株^(-1))、N3(10.5 g·株^(-1))和N4(13.5 g·株^(-1))5个氮素水平的氮肥施用试验,研究氮素营养对白檀幼苗生长、叶片叶绿素含量、光合参数与叶绿素荧光参数的影响。结果表明:适量施用氮肥显著促进了白檀幼苗株高、地径和叶片面积的生长,上述指标均在N2处理下达到最大值,分别较CK提高67.49%、50.00%、49.95%;与CK相比,4个氮肥处理不同程度地增加了叶片叶绿素含量,提升了净光合速率(Pn),促进了水分利用率(Wue),以N2处理的叶绿素含量、净光合速率(Pn)和水分利用率(Wue)最高,分别比CK提高63.6%、89.8%、79.9%;在暗适应条件下,白檀叶片光系统Ⅱ(PSⅡ);最大光化学效率(Fv/Fm)、实际光合效率(ΦPSⅡ)、光化学猝灭系数(qP)和表观光合电子传递速率(ETR)均随着施氮量的增加呈先上升后下降的趋势,并且均在N2处理下达到最大值,非光化学淬灭系数(NPQ)降低。综上所述,适量施用氮肥能显著提升白檀适应强光的能力和光合能力,促进白檀幼苗的生长。本试验条件下,白檀幼苗适宜的施氮量为7.10~7.86 g·株^(-1)。

To determine the optimal nitrogen fertilizer dosage for the rapid growth of Symplocos tanakana seedlings and enhance seedling cultivation efficiency,1-year-old Symplocos tanakana seedlings were used as experimental materials to set up 5 levels of nitrogen fertilizer application experiment,CK(0 g·plant^(-1)),N1(4.5 g·plant^(-1)),N2(7.5 g·plant^(-1)),N3(10.5 g·plant^(-1))and N4(13.5 g·plant^(-1)).The effects of nitrogen nutrition on seedling growth,chlorophyll content,photosynthetic parameters and chlorophyll fluorescence parameters of S.tanakana seedlings were studied.The results showed that appropriate nitrogen fertilizer application significantly promoted plant height,ground diameter,and leaf area of S.tanakana seedlings,with the highest values observed under N2 treatment,increasing by 67.49%,50.00%,and 49.95%compared to the control group.Chlorophyll content,net photosynthetic rate(Pn),and water utilization efficiency(Wue)also increased under 4 fertilization treatments,with peak values under N2 treatment showing increases of 63.6%,89.8%,and 79.9%compared to the control group.Maximum photochemical efficiency(FV/FM)under PSII dark adaptation,actual photosynthetic efficiency(ΦPS II),photochemical quenching coefficient(qP),and apparent photosynthetic electron transfer rate(ETR)of S.tanakana leaves initially increased and then decreased with nitrogen application,peaking under N2 treatment.Meanwhile,non-photochemical quenching coefficient(NPQ)decreased.In conclusion,proper nitrogen fertilizer application can enhance adaptability of S.tanakana to strong light,increase photosynthetic capacity,and effectively promote seedling growth.In this test,the optimal nitrogen supply was found to be 7.10-7.86 g·plant^(-1).