中文摘要：

化学合成肥料的大量使用导致土壤pH发生显著变化，但其对植物与根际微生物竞争吸收氨基酸的影响机制尚不明确．本试验通过电解法调节杭州红壤和铁岭棕壤两种土壤pH，采用外源添加15N标记甘氨酸短期吸收4h的方法，研究了pH对玉米及根际微生物竞争吸收氨基酸的影响．结果表明：土壤pH对玉米根和地上部生物量有显著影响，对于红壤，pH为6．48最适宜玉米生长，且玉米地上部15N丰度和15N．甘氨酸吸收量也显著高于其他处理；对于棕壤，pH为7．65最适宜玉米生长，其玉米地上部和根系15N丰度显著低于pH为5．78处理，但15N-甘氨酸吸收量显著高于其他处理．红壤pH为6．48条件下，其微生物生物量碳相对较高，而棕壤pH为7．65条件下，其微生物生物量碳相对较低．综合根系吸收、转运及微生物竞争吸收的结果，推断红壤在pH为6．48条件下虽然面临着微生物的竞争吸收，但生长于其上的玉米通过提高吸收速率和转移比率提高了氨基酸的吸收量；在pH为7．65的棕壤中，微生物活性较低，降低了与玉米竞争吸收氨基酸的能力，从而增加了玉米对氨基酸的吸收量．

英文摘要：

Organic nitrogen can play an important role in plant growth, and soil pH changed greatly due to the over-use of chemical fertilizers, but the effects of soil pH on the competitive uptake of amino acids by plants and rhizosphere microorganisms are lack of detailed research. To study the effects of soil pH on the uptake of amino acids by maize and soil microorganisms, two soils from Hangzhou and Tieling were selected, and the soil pH was changed by the electrokinesis, then the 15N-labeled glycine was injected to the centrifuge tube with a short-term uptake of 4 h. Soil pH had a significant effect on the shoot and root biomass 6.48 for Hangzhou red soil, while it was 7.65 , and the optimal pH for maize shoot growth for Tieling brown soil. For Hangzhou soil, was the 15N abundance of maize shoots under pH = 6.48 was significantly higher than under other treat- ments, and the uptake amount of 15N-glycine was also much higher. However, the 15N abundance of maize shoots and roots under pH = 7.65 Tieling soil was significantly lower than it under pH = 5.78, but the uptake amount of 15N-glycine under pH = 7.65 was much higher. The microbial biomass C was much higher in pH = 6.48 Hangzhou soil, while it was much lower in pH = 7.65 Tieling soil. Ac- cording to the results of root uptake, root to shoot transportation, and the competition with microor- ganisms, we suggested that although facing the fierce competition with microorganisms, the maize grown in pH = 6.48 Hangzhou soil increased the uptake of glycine by increasing its root uptake and root to shoot transportation. While in pH = 7.65 Tieling soil, the activity of microorganisms was de- creased, which decreased the competition with maize for glycine, and increased the uptake of gly- cine by maize.