摘要
为明晰紫花苜蓿-根瘤菌共生系统固氮能力的动态变化及高效固氮的发生阶段,提高苜蓿对氮素的转化与利用。以甘农9号紫花苜蓿和苜蓿中华根瘤菌菌株LL11共生组合为研究对象,分析比较接种根瘤菌后紫花苜蓿生长42 d内不同共生阶段的根瘤形态结构、固氮能力、植物表型、可溶性物质含量、氮代谢关键酶活性等指标的动态变化,采用熵权TOPSIS综合评价法探寻共生过程中高效固氮的发生阶段。结果表明:(1)随着共生天数的增加,有效根瘤数、根瘤直径和根瘤重逐渐增大,42 dpi(接种后天数)有效根瘤数(9.3个)、根瘤重(0.0309 g)和根瘤直径(1.43 mm)达到最大;而根瘤内部被侵染的根瘤细胞数目呈先增后减的趋势,35 dpi根瘤内部被侵染的根瘤细胞数目最多(992个);(2)35 dpi的固氮酶活性[0.9619μmol/(g·h)]、豆血红蛋白含量(2.6081 mg/g)、单株固氮潜力(0.0283μmol/h)均显著高于其他共生时期(P<0.05);(3)接种根瘤菌菌株LL11后,甘农9号紫花苜蓿的株高、根长、地上部和地下部干重均显著提升,并在21 dpi或35 dpi出现了增幅高峰(与对照组相比较),在42 dpi达到最大值;(4)根系中可溶性糖含量的最高值和最大增幅发生在21 dpi,而可溶性蛋白含量最高值和最大增幅发生在42 dpi;叶片和根系中的硝酸还原酶(NR)、亚硝酸还原酶(NiR)、谷氨酰胺合成酶(GS)、谷氨酸合成酶(GOGAT)这4类氮代谢关键酶活性均在35 dpi显著高于其他共生阶段(P<0.05)。通过熵权TOPSIS综合评价分析得出,35 dpi为高效固氮发生阶段,之后固氮效率开始下降。
This study investigated the temporal dynamics of nitrogen fixation efficiency in the symbiosis between alfalfa(Medicago sativa cv.Gannong No.9)and Sinorhizobium meliloti LL11.The objective was to identify the stage of optimal nitrogen fixation for improving nitrogen conversion and utilization in alfalfa.Over a 42-day period following rhizobia inoculation,the experiment evaluated changes in nodule morphology and structure,fixation capacity,plant phenotype,soluble substance content,and activities of key enzyme of nitrogen metabolism in alfalfa.The entropy-weighted technique for order preference by similarity to ideal solution(TOPSIS)method was employed to determine the stage of most efficient nitrogen fixation.The results showed that:(1)Effective nodule number,diameter,and weight all progressively increased until 42 days post-inoculation(dpi).The number of rhizobia-infected cells within nodules peaked at 35 dpi(992),followed by a decline.(2)Nitrogenase activity[0.9619μmol/(g·h)],leghemoglobins content(2.6081 mg/g),and nitrogen fixation potential per plant(0.0283μmol/h)all reached their highest levels at 35 dpi and were significantly higher compared to other time points(P<0.05).(3)Shoot height,root length,and dry weight of shoot and root in M.sativa cv.Gannong No.9 also exhibited significant increases,culminating at 42 dpi.(4)Soluble sugar content in roots peaked at 21 dpi,while soluble protein content reached its maximum at 42 dpi.Activities of nitrate reductase(NR),nitrite reductase(NiR),glutamine synthetase(GS),and glutamate synthetase(GOGAT)in both leaves and roots were significantly higher at 35 dpi compared to other stages(P<0.05).The entropy-weighted TOPSIS analysis identified 35 dpi as the stage of high-efficiency nitrogen fixation,followed by a decline thereafter.
作者
陆保福
康文娟
师尚礼
关键
景芳
LU Baofu;KANG Wenjuan;SHI Shangli;GUAN Jian;JING Fang(College of Prataculture,Gansu Agricultural University/Key Laboratory of Grassland Ecosystem of Ministry of Education,Lanzhou 730070,China)
出处
《中国草地学报》
CSCD
北大核心
2024年第6期36-48,共13页
Chinese Journal of Grassland
基金
国家自然科学基金项目(32101427)
甘肃省高等学校创新基金项目(2021A-062)。
关键词
紫花苜蓿
苜蓿中华根瘤菌
根瘤
固氮动态
氮代谢关键酶
Medicago sativa
Sinorhizobium meliloti
Root nodules
Nitrogen fixation dynamics
Key enzymes of nitrogen metabolism
