Effects of Phosphorus on plant growth and P conversion in root rhizosphere of different maize seedlings

To make the most of plant genetic potential and save phosphorus(P)mineral resources,the effects of high and low P levels on plant growth,root morphology,soil physiological characters in rhziosphere and non-rhziosphere and numbers of microorganisms were studied under conditions of pot culture with root-bag.Two maize(Zea mays L.) hybrids,'Liyu 16' and 'Jidan 28',were used as the testing materials.The results showed that compared with the high-P level,the height,total green leaf areas,shoot and root dry weight of two maize in low P level were reduced,while the ratio of root to shoot in dry weight increased.Moreover,soil pH was reduced,the phosphatase activity increased,numbers of bacteria and available P content lessened.Compared with non-rhziosphere,pH,phosphatase activity and available P content in rhziosphere were reduced while numbers of bacteria and actinomycete increased,but not related with P levels.Plant biomass and P content were positively related with root length,root surface area and bacteria number,but had no correlation with dry weight of root.Therefore,root morphology,pH and bacteria number in rhziosphere were the main factors affecting plant growth.Compared with 'Jidan28' cultivar,'Liyu 16' had higher height,total green leaf areas,dry weight and P content.Larger root length,root surface area,ratio of root to shoot,and more bacteria number may be the primary physiological mechanism leading 'Liyu16' to possess the capacity of higher-efficient-uptake-P.