外源壳聚糖对低氮胁迫下菜用大豆结瘤固氮及光合作用的影响

Effects of Exogenous Chitosan on Nodulation and Nitrogen Fixation and Photosynthetic Characteristics of Vegetable Soybean under Low Nitrogen Stress

糖类是豆科植物结瘤过程中重要的碳源和能源,而糖类主要来源于光合作用。为探讨低氮胁迫下外源壳聚糖对菜用大豆结瘤固氮及光合作用的影响,以蛭石为基质,菜用大豆品种“日本青”-快生型根瘤菌HH103共生体为试材,采用人工气候箱培养,以铵态氮与硝态氮为氮源,研究低氮胁迫下壳聚糖对菜用大豆结瘤数、植株干物质量、植株氮含量及光合参数的影响。结果表明:铵态氮与硝态氮的低氮胁迫均导致菜用大豆各指标均显著下降;而铵态氮与硝态氮的低氮胁迫在壳聚糖处理后,根瘤数、植株氮含量、干物质量显著升高,Pn、Gs、Tr升高,Ci下降,其中,植株氮含量增幅分别高达47.55%和43.24%。综上,壳聚糖通过促进低氮胁迫下菜用大豆光合作用,为植株生长发育及结瘤固氮提供较充足的碳源和能源,同时,高水平的物质合成与转运能力也可有效缓解低氮胁迫对植物体的抑制作用。这可能是壳聚糖提高低氮胁迫下菜用大豆结瘤固氮的重要原因之一。

Sugars are important carbon and energy sources in the nodulation process of legumes,and sugars are mainly derived from photosynthesis.In order to investigate the effects of exogenous chitosan on nodulation,nitro⁃gen fixation and photosynthesis of vegetable soybean under low nitrogen stress,the effects of chitosan on nodula⁃tion number,plant dry weight,plant nitrogen content and photosynthetic parameters of vegetable soybean under low nitrogen stress were studied by using vermiculite as substrate,vegetable soybean variety‘Nippon green’-rap⁃id-growing rhizobia HH103 symbiont as test material,artificial climate box culture,ammonium nitrogen and ni⁃trate nitrogen as nitrogen sources.The results showed that the low nitrogen stress of ammonium nitrogen and ni⁃trate nitrogen resulted in a significant decrease in each index of vegetable soybean.Under the low nitrogen stress of ammonium nitrogen and nitrate nitrogen,after chitosan treatment,the nodule number,plant nitrogen content and dry matter quality increased significantly,while Pn,Gs and Tr increased and Ci decreased,and the plant ni⁃trogen content increased by 47.55%and 43.24%respectively.In summary,chitosan provided sufficient carbon and energy sources for plant growth,development and nodulation nitrogen fixation by promoting photosynthesis of vegetable soybean under low nitrogen stress.At the same time,high levels of substance synthesis and transport capacity can also effectively alleviate the inhibition of low nitrogen stress on plants.This may be one of the im⁃portant reasons for chitosan to improve nitrogen fixation of vegetable soybean under low nitrogen stress.