土壤悬液培养法研究长期施肥下花生根际解磷菌溶磷特性

Study on Characteristics of Phosphorus-Dissolving Microbial Dissolvig Phosphorus in Peanut Rhizosphere under Long-term Fertilization with Soil Suspension Cultivation Method

基于长期野外定位试验和室内土壤悬液培养,研究长期不同有机与无机肥料配施(纯化肥(NPK)、化肥与厩肥配施(NPKM)和化肥与稻草秸秆配施(NPKS))下,花生根际土壤解磷菌对Ca_3(PO_4)_2(Ca-P)、FePO_4(Fe-P)和AlPO_4(Al-P)的溶解特性。结果表明:有机无机肥配施促进了解磷菌的繁殖,在Ca-P和Fe-P固体NBRIP(国际植物研究所磷酸盐生长培养基)培养基中,NPKM处理可培养解磷菌密度分别为6.15和5.80 log(cfu g-1 dry soil),高于其他处理。在分别以Ca-P、Fe-P和Al-P为唯一磷源的NBRIP液体培养基中添加土壤悬液培养9 d发现,NPKM处理对Fe-P和Al-P的最高溶磷量分别为221.8 mg kg^(-1)和205.5 mg kg^(-1);NPKS处理对Ca-P的溶解有明显的优势。相比于单一菌株,解磷菌溶磷能力无绝对优势,但更能反映田间复杂条件下实际溶磷效果。通过土壤悬液培养法,从微生物群体角度发现:长期无机肥和厩肥配施更能促进花生根际解磷菌的繁殖以及对无机磷的溶解,从而改善土壤缺磷状况,提高花生生物量和产量。

【Objective】The study was oriented to explore characteristics of phosphate-dissolving microbial （PDM） in peanut rhizosphere dissolving Ca3（PO4）2 （Ca-P）, FePO4 （Fe-P） and AlPO4 （Al-P） as affected by fertilization in a 28-year long-term fertilization field experiment designed to have three fertilization treatments, i.e. NPK （pure chemical fertilizer-NPK）, NPKM （combined fertilization of chemical fertilizer and pig manure） and NPKS （combined fertilization of chemical fertilizer and rice straw） in the red soil region. 【Method】Soil samples were collected from the three treatments of the long-term field experiment for preparation of soil suspensions with NBRIP （National Botanical Research Institute Phosphate） （containing 10 g L-1 glucose, 2.5 g L-1 MgCl2, 0.25 g L-1 MgSO4.7H2O, 0.2 g L-1 KCl, 1 g L-1 （NH4）2SO4, 15 g L-1 agar, pH 7.0, and 5 g L-1 Ca3（PO4）2 for the Ca–P test, 4.86 g L-1 FePO4 for the Fe–P test, and 3.93 g L-1 AlPO4 for the Al–P test）, separately. Then the suspensions were incubated in lab and analyzed for variation of available phosphorus （AP） in and pH of the suspensions relative to treatment of the long-term fertilization experiment. In the experiment field of acidic soil, N, P and K was applied at a rate of 110 kg hm-2, 29 kg hm-2, 142 kg hm-2 in the form of urea, （NH4）2HPO4 and KCl, respectively, and combined fertilization was done at a ratio of 7：3 on N input basis （chemical fertilizer and composted pig manure or straw）. Each fertilization treatment had three replicates, 34.6 cm2 in plot size. The plots were laid out randomly and separated with cement boards （20 cm above ground, 30 cm below ground）. 【Result】Results show that the treatments of combined fertilization stimulated propagation of PDM. In Treatments NPKM of the Ca-P and Fe-P types, PDM was 6.15 and 5.80 log （cfu g-1 dry soil） in density, respectively, higher than in all the other treatments. Among the treatments, Treatment NPKM was the highest in phosphorus solubilizing capacity and reached up to 221.8 mg kg-1 in Fe-P and 205.5 mg kg-1 in Al-P, or 134.6%~144.6% and 10.48%~153.2% higher than that in the other two treatments after 3 and 5 days of incubation, while Treatment NPKS was unique in ability to dissolve Ca-P, which was 21.33% and 24.57% higher than that in Treatment NPKM and NPK. Comparing to a single strain of bacteria, PDM did not show any absolute advantages, but it did reflect the real phosphate-dissolving effect under complicated field conditions and the effects of different fertilization treatments on phosphate-dissolving bacteria groups.【Conclusion】 Therefore, it is found that long-term combined fertilization is more capable of stimulating propagation of PDM groups and hence dissolving more inorganic phosphorus in peanut rhizosphere soil. Consequently, soil P supply is improved and biomass/yield of peanut raised.