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采用盆栽试验,以甜菜(Beta vulgaris L.)品种双丰16和甜研7为试材,研究了不同水平氮素处理对甜菜苗期植株生长、叶片光合色素含量、RuBP羧化酶活力、气体交换和叶绿素荧光参数的影响。结果表明,不同甜菜品种植株叶面积、各部位生物量、全氮和可溶性蛋白含量、RuBP羧化酶活力以及气体交换参数均随施氮量的增加呈先升高后降低的趋势;氮素对苗期甜菜地上部生长的促进作用大于地下部,氮素供给后根冠比、叶片比叶重显著降低;此外,甜菜叶片光合色素含量、PSII最大光化学量子产量(F v/F m)、开放的PSII原初光能捕获效率(F’v/F’m)以及PSII实际光化学效率(Y(II))均随施氮量的增加而上升,调节性非光化学淬灭系数(Y(NPQ))随施氮量的增加而下降。同时,调节性非光化学淬灭(NPQ)和快速暗弛豫(NPQ F)均显著受氮素的影响(P<0.05)。本试验条件下,适量施氮(60~180kg·hm-2)可通过提高光合色素含量、PSII潜在活性及PSII光化学最大效率,减少荧光非化学淬灭系数,避免光抑制的产生等改善光化学活性的途径,以及增强叶片的气孔导度和羧化能力,进而有助于提高甜菜植株的光合特性,促进其生长和产质量的形成。过多施氮对甜菜幼苗光合与生长的促进效应降低。
A pot experiment was conducted to study the effects of different nitrogen levels on the plant growth, photosynthetic pigment content, activity of RuBP carboxylase, Exchange and chlorophyll fluorescence parameters. The results showed that the leaf area, biomass, total nitrogen and soluble protein content, RuBP carboxylase activity and gas exchange parameters of different sugar beet varieties increased firstly and then decreased with the increase of nitrogen application rate. In addition, the root-shoot ratio and specific leaf weight of the sugar beet significantly decreased after the nitrogen supply. In addition, photosynthetic pigment content, maximum photochemical quantum yield of PSII (F v / F m) The initial photon capture efficiency (F’v / F’m) of PSII and the actual photochemical efficiency of PSII (Y (II)) increased with the increase of nitrogen application rate. The regulatory non-photochemical quenching coefficient With the increase of nitrogen rate decreased. At the same time, both NPQ and NPQ F were significantly affected by nitrogen (P <0.05). Under the conditions of this experiment, applying suitable amount of nitrogen (60-180 kg · hm-2) can improve the photochemical activity by increasing the photosynthetic pigment content, the potential activity of PSII and the maximum photochemical efficiency of PSII, reducing the non-chemical quenching coefficient of fluorescence and avoiding the generation of photoinhibition And enhance the stomatal conductance and carboxylation ability of the leaves, thereby helping to improve the photosynthetic characteristics of sugar beet plants and promote their growth and yield and quality formation. Excessive nitrogen application reduced the photosynthesis and growth of sugar beet seedlings.