氮素形态对铁线莲光合特性及氮代谢的影响

Effect of Nitrogen Forms on Photosynthetic Characteristics and Nitrogen Metabolism of Clematis

摘要:

为了解铁线莲的光合性能和氮素代谢的响应机制，对不同氮素形态配比下1 a生厚叶铁线莲（Clematis crassifolia）与天台铁线莲（C.paten ssp.tientaiensis）的生长、光响应曲线、A-Ci曲线和氮代谢相关酶活性进行了比较。结果表明，氮素形态配比显著影响铁线莲的生物量和叶绿素（Chl）含量，厚叶铁线莲在铵态氮（NH₄⁺-N）与硝态氮（NO₃^--N）配比为1：1时，生物量、Chl a、Chl b、Car含量达到最大；天台铁线莲的Chl a和Chl b含量在NH₄⁺-N/NO₃^--N为1：3时最高。在NH₄⁺-N/NO₃^--N为1：1时，厚叶铁线莲的光饱和点和天台铁线莲的光补偿点为最大值，且厚叶铁线莲叶片的Vc_max与J_max值均显著高于其他处理。天台铁线莲的谷氨酰胺合成酶（GS）活性在NH₄⁺-N/NO₃^--N为3：1处理下最高，而硝酸还原酶（NR）和亚硝酸还原酶（NiR）活性在NH₄⁺-N/NO₃^--N为1：3时显著高于其他处理。可见，NH₄⁺-N和NO₃^--N混合施用能有效促进2种铁线莲的生长和光合作用，加强氮素利用效率。厚叶铁线莲适宜的NH₄⁺-N/NO₃^--N配比为1：1，而天台铁线莲更适宜1：3。

Abstract:

In order to understand the photosynthetic characteristics and response mechanism of nitrogen metabolism in Clematis, the growth, light response curve, A-Ci curve and nitrogen metabolism related enzyme activities of 1-year-old Clematis crassifolia and C. paten ssp. tientaiensis were studied under different ratios of NH₄⁺-N:NO₃^--N. The results showed that the ratio of NH₄⁺-N:NO₃^--N significantly affects the biomass and chlorophyll content of clematis, and the biomass, Chl a, Chl b, and Car contents of C. crassifolia reach the maximum under the ratio at 1:1, while the Chl a and Chl b contents of C. paten ssp. tientaiensis reach the maximum under the ratio at 1:3. Under the ratio of 1:1, the light saturation point (LSP) of C. crassifolia and the light compensation point (LCP) of C. paten ssp. tientaiensis were the maximum, and the V_cmax and J_max values of C. crassifolia leaves were significantly higher than those under other ratios. The glutamine synthetase (GS) activity of C. paten ssp. tientaiensis was the highest under the ratio of 3:1, while NR and nitrite reductase (NiR) activities under the ratio at 1:3 were significantly higher than those under other ratioes. Therefore, the mixed application of NH₄⁺-N and NO₃^--N could effectively promote the growth and photosynthesis, and enhance the nitrogen utilization efficiency of two Clematis. C. crassifolia was suitable for 1:1 of NH₄⁺-N to NO₃^--N, while C. paten ssp. tientaiensis was more suitable for 1:3.