| The effects of genetically modified crops(GMCs) on the phosphorus forms and soil microbial community were one of the main content of ecological security evaluation. In the experiment with phosphorus fertilizer application or no phosphorus fertilizer application, this study explored the effects of P-efficient transgenic rice(OsPT4) on richness and evenness of soil bacterial community and the forms of inorganic phosphorus. This study could provide theoretical support for comprehensive evaluation of the biosafety of P-efficient transgenic rice. The main results were as follows:1. The root length and plant dry weight of OsPT4 were significantly higer than PHO2 and Nipponbare(P<0.05), but the plant height of Nipponbare was significantly higher than the two P-efficiency materials(P<0.05). The total P concentration of stem and leaf, spike with three materials were the same, all behaved as PHO2> OsPT4> Nipponbare. The total P concent of various parts with PHO2 was signicicantly higher than OsPT4(P<0.05).2. After the phosphorus fertilizer added, the total P of Nipponbare was higher than OsPT4, PHO2 in the rice elongation stage, the rice heading and flowering period(P<0.05). Without phosphorus fertilizer application, the total P of Nipponbare was signicicantly higher than OsPT4 and PHO2 only in the rice elongation stage(P<0.05). After the phosphorus fertilizer added, there was no significant effects of the OsPT4 on the concent of soil available phosphorus. Only in the rice elongation stage, there was significant difference between OsPT4, PHO2 and Nipponbare(P<0.05). Without phosphorus fertilizer application, the changing trend of soil available phosphorus in the whole growth stage was the same. But the concent of available phosphorus of OsPT4 was significantly higher than Nipponbare and PHO2(P<0.05), only in the rice mature stage. The changing trend of the alkaline phosphatase activity of three materials in the whole stage was the same. After the phosphorus fertilizer was added, there was no significant difference of soil alkaline phosphatase activity between the three materials besides the rice elongation stage. Without phosphorus fertilizer application, the activity of alkaline phosphatase of OsPT4 was significantly higher than PHO2 and Nipponbare(P<0.05). Therefore, the effects of P-efficiency transgenic rice on soil total P, available phosphorus, alkaline phosphatase activity were different, depending on the growth period of rice and the fertilizer treatment.3. Significantly higer dry weight and P accumulation were observed in OsPT4 and PHO2 than in Nipponbare(P<0.05), but significantly lower total P and inorganic phosphorus contents were observed in OsPT4 and PHO2 than in Nipponbare(P<0.05). The contents of inorganic phosphorus fractions in the Rhizosphere and non-rhizosphere soil were sorted as follows: O-P>Fe-P>Al-P>Ca-P, and the order of inorganic phosphorus fractions adapted to three rice materials. The concents of O-P, Fe-P, Al-P of the tree rice varieties all showed no significant difference between the rhizosphere soil and the non-rhizosphere soil under the same treatment. The concent of Ca-P of Nipponbare had no significant difference between the rhizosphere and the non-rizosphere soil. After the phosphorus fertilizer was added, the concentration of Ca-P in the OsPT4 and PHO2?s non-rhizosphere soil was higher than the rhizosphere soil(P<0.05); But witout phosphorus fertilizer, the concentration of Ca-P in the OsPT4 and PHO2?s non-rhizosphere soil was lower than the rhisosphere(P<0.05).4. The bacterial 16 S rDNA DGGE fingerprintings showed no significant differences in community structure between P-efficient transgenic rice, Nipponbare and P-efficient mutant rice with the same P fertilizer application treatment during the same growing stage. With P fertilizer application, compared with OsPT4 and Nipponbare, PHO2 had one electrophoretic band increasing in the rice elongation stage, the increased band belonged to the families of cyanobacterium, Cyanobactteria; OsPT4 missed one electrophoretic band compared to that in the Nipponbare during the rice heading and flowering period, and the reduced band belonged to Gemmatimonadetes. Without P fertilizer application, OsPT4 had increased four electrophoretic bands during both the rice tillering stage and maturation stage compared with Nipponbare, and the four electrophoretic bands belonged to Geobacter of Proteobacteria, Bacillus of Firmicutes, Chloroflexi, Geobacter of Proteobacteria. So P-efficient Transgenic Rice(OsPT4) had significant effects on richness(S), Shannon-wiener index(H) and evenness(EH) of soil bacteria at certain rice growing stage, and P fertilizer application also took part in these influences. |
