东北山樱根际荧光假单胞菌对幼苗根系呼吸及生长的影响

Effects of Pseudomonas fluorescens inoculation on root respiration and plant growth of Cerasus sachalinensis seedlings

【目的】探讨根际优势细菌对东北山樱幼苗根系功能的影响机制,为樱桃园根际环境调控提供参考依据。【方法】以东北山樱幼苗为试材,进行土壤接种荧光假单胞菌(Pseudomonas fluorescens)处理,通过测定土壤微生物生物量碳、根系呼吸速率、幼苗生长量等指标,分析幼苗对接种根际优势细菌的响应特征。【结果】与对照相比,接种荧光假单胞菌的处理土壤微生物生物量碳短期内提高了22.7%、幼苗根系总呼吸速率增加了39.5%、呼吸途径前期以糖酵解途径—磷酸戊糖途径—细胞色素途径(EMP-PPP-COX)为主,而后期转变为以糖酵解途径—三羧酸循环—细胞色素途径(EMP-TCA-COX)为主。不同时间呼吸代谢关键酶活性不同,接种处理前期显著降低了磷酸果糖激酶(PFK)、苹果酸脱氢酶(MDH)活性,而后期显著增加了苹果酸脱氢酶(MDH)活性。接种处理对幼苗生长量无明显影响。【结论】接种荧光假单胞菌对土壤微生物生物量碳的影响存在短期效应。幼苗根系呼吸代谢过程对接种处理的响应有一个滞后期,即一般在处理结束20 d后,根系呼吸途径分配比例,部分相关酶活性发生改变,影响根系总呼吸速率,但最终对幼苗生长量无明显影响。

【Objective】 The aims of the study were to investigate the mechanisms of Cerasus sachalinensis Kom. seedlings responding to inoculation of Pseudomonas fluorescens and provide the academic and practical basis for regulating the cherry orchard rhizosphere soil. 【Method】 Cerasus sachalinensis Kom.seedlings were treated with Pseudomonas fluorescens inoculation, and changes of root respiratory pathways, related enzyme activities, respiratory substrates and chlorophyll fluorescence parameters of leaves were tested. The mechanisms of C. sachalinensis Kom. seedlings responding to Pseudomonas fluorescens inoculation were compared and analyzed. 【Result】 The results showed that compared with CK, the microbial biomass carbon(MBC) was significantly increased by 22.7%, total root respiration was significantly increased by 39.5% in the treatment. Embden-meyerhof-parnaspathway(EMP), pentose phosphate pathway(PPP), and cytochrome oxidase pathways(COX) were the dominant respiratory pathways at first, then the respiration pathways were changed to the Embden-meyerhof-parnaspathway, tricarboxylic acid cycle(TCA), and cytochrome oxidase pathways after C. sachalanensis seedlings were subjected to the treatment.Malate dehydrogenase(MDH) and phosphofructokinase(PFK) activities significantly changed in response to Pseu treatments. Although Pseu treatment changed total respiration rate and key enzymes activities,however the treatment had no significant effect on seedlings growth. 【Conclusion】 Inoculation with Pseudomonas fluorescens have short-term effect on MBC. However the there exists a short time lag between the respond to MBC and seedlings. In general, 20 days after inoculation can change the rate of respiration pathway, key enzyme activity and influence the function of roots, but have no significant effect on seedling growth.