施用氮肥对橡胶林下套种的谢君蘑芋光合系统重要特征及相关生化指标的影响

Effects of applying nitrogen fertilizer on important characteristics of photosynthetic system and related biochemical indexes of Amorphophallus xiei interplanted under rubber plantation

以橡胶林下套种的谢君蘑芋(Amorphophallus xiei H.Li et Z.L.Dao)为研究对象,对施用150 kg·hm-2氮肥后其叶绿素荧光参数、光响应和CO2响应曲线及相关光合参数、光合诱导曲线及相关参数、PSⅡ能量分配的变化进行了研究,并对叶片的全氮含量、抗氧化系统相关指标、叶绿素和叶黄素含量及相关指标进行了比较分析。结果表明:与对照组(不施氮肥)相比,处理组(施氮肥)谢君蘑芋的最小叶绿素荧光值(F0)极显著降低、最大叶绿素荧光值(Fm)极显著升高,最大光化学效率(Fv/Fm)也有一定程度的提高;处理组和对照组间的光响应曲线、CO2响应曲线及光合参数均差异明显,其中,处理组的净光合速率(Pn)高于对照组,其最大净光合速率(Pmax)、光饱和点(LSP)和羧化效率(CE)均极显著高于对照组,而暗呼吸速率(Rd)、表观量子产量(AQY)和光补偿点(LCP)与对照组无显著差异;完成50%和80%光合诱导所需的时间均低于对照组,但差异不显著。与对照组相比,在光响应过程中处理组PSⅡ中用于光合碳同化的能量(ΦPSⅡ)明显增大、用于非光化学淬灭的能量(ΦNPQ)明显减小、用于荧光耗散的能量(Φf.d)变化不明显,而在光合诱导过程中则表现为ΦPSⅡ略减小、ΦNPQ减小、Φf.d增大。与对照组相比,处理组叶片的全氮含量以及超氧化物歧化酶和过氧化物酶活性均极显著升高,氧自由基含量极显著降低,谷胱甘肽含量显著升高,而丙二醛和抗坏血酸含量以及过氧化氢酶、抗坏血酸过氧化物酶、单脱氢抗坏血酸还原酶和脱氢抗坏血酸还原酶活性变化不显著;叶片中的叶绿素和β-胡萝卜素含量均显著高于对照组,新黄质、叶黄质、紫黄质和花药黄质含量以及紫黄质、花药黄质和玉米黄质的总含量均极显著高于对照组,而玉米黄质含量和叶黄素转化率则极显著低于对照组。综合分析结果显示:施用氮肥能够增强橡胶林下套种的谢君蘑芋的光合作用能力、减少过剩光能、降低活性氧伤害,并减轻光胁迫的危害程度。

Taking Amorphophallus xiei H. Li et Z. L. Dao interplanted under rubber plantation as research objects, changes of its chlorophyll fluorescence parameters, light response and CO2 response curves and related photosynthetic parameters, photosynthetic induction curve and related indexes, energy allocation of PS I] were investigated after applying 150 kg·hm-2 nitrogen fertilizer, and total nitrogen content, related indexes of antioxidant system, chlorophyll and xanthophyll contents and related indexes in leaf were comparatively analyzed. The resuhs show that compared with the control group （not applying nitrogen fertilizer）, the minimum chlorophyll fluorescence （ F0） of A. xiei of treatment group （ applying nitrogen fertilizer） decreases extremely significantly, the maximum chlorophyll fluorescence （Fm ） increases extremely significantly, the maximum photochemical efficiency （Fv/Fm ） also increases at a certain degree. There are obvious differences in light response curve, CO2 response curve and photosynthetic parameters between treatment group and the control group, in which, net photosynthetic rate （Pn） of treatment group is higher than that of the control group, its the maximum net photosynthetic rate （Pmax）, light saturation point （LSP） and carboxylation efficiency （CE） all are extremely significantly higher than those of the control group, while its dark respiration rate （Rd）, apparent quantum yield （AQY） and light compensation point （LCP） have no significant difference from those of the control group. Required times for completing 50% and 80% light induction of treatment group are lower than those of the control group, but the difference is not significant. Compared with the control group, during light response process, energy used for photosynthetic carbon assimilation （ ФPSⅡ ） in PS Ⅱ of treatment group increases obviously, energy used for non photochemical quenching （ФNPQ） decreases obviously and change of energy used for fluorescence dissipation （Фf.d） is not obvious, while during photosynthetic induction process, ФPSⅡ decreases slightly, ФNPQ decreases and Фf.d increases. Compared with the control group, total nitrogen content and activities of superoxide dismutase and peroxidase in leaf of treatment group all increase extremely significantly, oxygen free radical content decreases extremely significantly, glutathione content increases significantly, while changes in contents of malondialdehyde and ascorbic acid, and activities of catalase, ascorbate peroxidase, monodehydrogenation ascorbate reductase and dehydrogenation ascorbate reductase are not significant. Contents of chlorophyll and β-carotene in leaf both are significantly higher than those of the control group, contents of neoxanthin, lutein, violaxanthin and antheraxanthin and total content of violaxanthin, antheraxanthin and zeaxanthin all are extremely significantly higher than those of the control group, while zeaxanthin content and xanthophyll conversion percentage are extremely significantly lower than those of the control group. The comprehensive analysis result indicates that applying nitrogen fertilizer can enhance photosynthetic capacity of A. xiei interplanted under rubber plantation, decrease excess light energy, reduce damage of reactive oxygen, and alleviate injury of light stress.