Effects of Light Intensity and Nitrogen Forms on Carbon and Nitrogen Metabolism in Cotton Arbuscular Mycorrhizal Fungi Symbionts
Inoculating arbuscular mycorrhiza(AM)fungi can improve the absorption of nitrogen(N)by cotton,but the effects of light intensity and N form on the growth and carbon and nitrogen(C-N)metabolism of cotton-AM fungal symbionts are rarely reported.In this experiment,upland cotton(Gossypium hirsutum L.)and AM fungi(Rhizopha-gus irregularis)were used as the research objects.Different light intensities(20% 2390 lux,60% 7170 lux,80% 9598 lux)and different forms of N(ammonium sulfate,potassium nitrate,urea,glutamine)with total N concentra-tion of 4 mmol/L were used as the test factors,the effects of different light intensities and nitrogen treatments on the growth and C-N metabolism of cotton-AM fungal symbionts were investigated by three-chamber culture and isotope tracing techniques.The study found that under the treatment of ammonium sulfate or urea,the abundance of mycorrhi-zal 15 N increased with the increase of light intensity,indicating that when the light intensity increased,the host plant might transmit more C to AM fungi,thus enabling AM fungi to assimilate and transport more exogenous N(especially N source containing NH4+)to the host plant.Under 60% and 80% light treatment,the AM fungal infection intensity of each N treatment was significantly higher than that of 20% light treatment,but there was no significant difference between 60% and 80% light treatment.Under 20% and 60% light treatment,applying urea or ammonium sulfate is more beneficial to the accumulation of N,P,and soluble sugar and chlorophyll in mycorrhizal cotton.Under 80% light treatment,applying ammonium sulfate is the most beneficial to the accumulation of symbiotic N,P and potassium nitrate is the most beneficial to the accumulation of symbiotic soluble sugar and chlorophyll.However,as compared with 20% light treatment in each N element group,the accumulation of symbiotic N,P and chlorophyll has decreased under 80% light.To sum up,applying4 mmol/L ammonium nitrogen(NH4+-N)at 60% light intensity is more con-ducive to the growth and development of cotton-AM fungal symbionts and C-N metabolism.
light intensitycottonarbuscular mycorrhizal fungisymbiontcarbon and nitrogen metabolismisotope
NETL
NSTL
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