| This study investigated the effects of two nitrogen fertilizer level[300 kg·hm-2（N1）and 360 kg·hm-2（N2）]and four planting patterns[sweet maize//vegetable soybean2:3（S2B3）and 2:4（S2B4）,sole sweet maize（SS）and sole soybean（SB）]on the arbuscular mycorrhizal fungi colonization of sweet maize and soybean rhizobia under the condition of no inoculation of arbuscular mycorrhizal fungi（AMF）and Rhizobium in the experimental farm of South China Agriculture,Guangzhou,Guangdong Province from autumn 2014 to spring 2016.The aim of the study was to explore the effects of reduced nitrogen inputs and intercropping soybean on the sweet maize yield,agronomic traits and nutrient absorption and provide scientific basis for reducing the input of chemical nitrogen fertilizer in the production of sweet maize to in Southern China.The main results were as follows:1.The four seasons（from the Autumn 2014 to the Spring 2016）field experiment results showed that:（1）There was no significante differences between the sweet maize yield of reduced nitrogen input treatment and conventional nitrogen input treatment.The nitrogen application rate of 300 kg·hm-2 was able to fit the normal growth demand of sweet maize and excessive application of nitrogen fertilizer do not increase the yield of sweet mazie.（2）The LER of intercropping treatments in the Autumn 2014 and the Spring 2016were greater than 1.The LER of intercropping treatments in 2015 was close to 1.The LER of conventional nitrogen input treatments in S2B4 was significantly higher than that of S2B3 in the Spring 2016.（3）There were no significant differences among the sweet maize height,stem diameter,ear height and yield at the different planting patterns and nitrogen input levels in four experiments seasons.2.The field experiment of autumn 2015 and the spring 2016 showed that:（1）There was no significant difference in the AMF infection rate,the absorption of nitrogen and phosphorus and the biomass between the chemical nitrogen reducing and conventional nitrogen treatment of sole sweet maize.（2）Under the application treatment of reducing nitrogen,the AMF infection rate of sweet maize and soybean were significantly higher than that of conventional nitrogen treatment in the intercropping system.However,the absorption of N and P,the biomass of sweet maize and soybean were no significant difference among above treatments.3.The analysis of roots and rhizosphere soil AMF 18S rDNA-DGGE of sweet maize and soybean showed that:（1）There was no significant difference between the Shannon index and the Simpson index of sweet maize,soybean roots AMF community among all different treatments in the spring 2016.（2）The rhizosphere soil AMF community Shannon index of sweet maize and soybean of S2B3-N2 treatment was significantly higher than that of S2B3-N1 treatment,while the rhizosphere soil AMF community Simpson index of sweet maize S2B3-N2 treatment was significantly lower than that of S2B3-N1 treatment.（3）The DNA fingerprints of sweet maize were affected by the cropping patterns and nitrogen input levels,but the DNA fingerprints of soybean was only affected by nitrogen input levels.4.In four seasons of the experiments,（1）The soybean nodule number and nodule dry weight of reduced N application S2B3 treatment were increased by 34.49%and 62.01%as compared with that of conventional nitrogen application treatment,respectively.The soybean nodule number and nodule dry weight of reduced N application S2B4 treatment were increased by 2.76%and 14.01%as compared with that of conventional nitrogen application treatment,respectively.Reduced nitrogen application increased the soybean nodulation in sweet maize-soybean intercropping.（2）Intercropping soybean promoted the nitrogen absorption of sweet maize,the nitrogen absorption of sweet maize of S2B3-N1and S2B4-N1 were increased by 27.64%and 13.49%than that of SS-N1,and S2B3-N2 and S2B4-N2 were increased by 29.27%and 24.34%than that of SS-N2,respectively. |
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