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采用营养液砂培试验,研究不同供镁水平对油桐幼苗生长、光合特性及叶绿素荧光参数等的影响。结果表明,低镁浓度(Mg2+<2 mmol·L-1)显著抑制了油桐的生长,叶绿素含量、Ru BP羧化酶及PEPC活性、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、气孔限制值(Ls)、水分利用效率(WUE)、最大光化学效率(Fv/Fm)、实际光化学量子效率(ΦPSII)、PSII的潜在活性(Fv/Fo)及光化学淬灭系数(q P)显著下降(P<0.05),胞间CO2浓度(Ci)、初始荧光(Fo)、非光化学淬灭系数(NPQ)有所升高;高镁浓度(Mg2+>4 mmol·L-1)也抑制了油桐幼苗的生长,导致叶片叶绿素含量、Ru BP羧化酶活性、Pn、Gs、Fv/Fm、Fv/Fo及q P均下降(P<0.05);随着供镁水平的增加,油桐的生长量、叶绿素含量、Ru BP羧化酶及PEPC活性、Pn呈先增加后降低的趋势;当镁离子浓度为2~4 mmol·L-1时,有利于油桐幼苗正常生长,缺镁胁迫下油桐光合速率的下降主要是由光合机构活性降低的非气孔因素引起的。
The sand culture experiment of nutrient solution was used to study the effects of different levels of magnesium supply on the growth, photosynthetic characteristics and chlorophyll fluorescence parameters of seedling. The results showed that Mg2 + <2 mmol·L-1 significantly inhibited the growth, the chlorophyll content, the activities of Ru BP carboxylase and PEPC, Pn, Gs, Transpiration rate (Tr), stomatal limitation (Ls), water use efficiency (WUE), maximum photochemical efficiency (Fv / Fm), actual photochemical quantum efficiency (ΦPSII), potential activity of PSII (Fv / Fo) (P <0.05), the intercellular CO2 concentration (Ci), the initial fluorescence (Fo) and the non-photochemical quenching coefficient (NPQ) were significantly increased; the concentration of Mg2 +> 4 mmol·L -1) also inhibited the growth of seedlings of P. tung, which led to the decrease of chlorophyll content, Ru BP carboxylase activity, Pn, Gs, Fv / Fm, Fv / Fo and q P Pn increased initially and then decreased with the increase of Ca (superscript 2 +) concentration, the growth of tung tree, chlorophyll content, Ru BP carboxylase activity and PEPC activity. When the concentration of magnesium ions was 2 ~ 4 mmol·L-1, The normal growth of seedlings under magnesium deficiency decreased the photosynthetic rate of Paulownia is mainly caused by the non-stomatal factors that reduce photosynthetic activity.