Study On Phosphate Solubilization And Biological Effects Of Penicillium Oxalicum HB1

Phosphate solubilizing microorganisms play an important role in the soil phosphorous cycling.The previous experiments isolated the strain of Penicillium oxalicum HB1 from soil,which could mobilize insoluble P in soil.However,it is not clear the ability of this fungus mobilizing mineral P.A serial of experiments were set up to investigate the phosphorous solubilizing ability of Penicillium oxalicum HB1 in agar medium,nutrient solution and soil.Meanwhile,germination experiment and pot experiment were conducted to explore the effects of Penicillium oxalicum HB1 on the vegetables seeds germination,vegetables seedling growing and the soil biological properties.The main results were as follows:?1?The transparent circle appeared on the agar medium of petri dish with calcium phosphate,phosphate rock powder,iron phosphate and aluminum phosphate individually when Penicillium oxalicum HB1 was incubated in the growth medium.It indicated that Penicillium oxalicum HB1 could dissolve P from different phosphate mineral.When calcium phosphate was used as the P source and NH₄⁺-N,NO₃^--N as nitrogen source,the maximum available P concentrations in P.oxalicum HB1 broth were 884 mg/L and 954mg/L.When phosphate rock powder was used as the P source and NH₄⁺-N as nitrogen source,the available P concentration dissolved by HB1 was up to 199 mg/L.When phosphate ore was used as P source,the available P content in P.oxalicum HB1 broth with NH₄⁺-N or NO₃^--N was 265 mg/L or 206 mg/L.When aluminum phosphate was used as P source and NO₃^--N as nitrogen source,the available P concentration in medium with HB1was 120 mg/L.Therefore,P.oxalicum HB1 had the highest P dissolving capacity for calcium phosphate.?2?HB1 incubation in soil for 21 days,in the low phosphorus soil,the concentration of available phosphorus in soil with HB1 addition was increased by 45.00%compared to the control.However,in high phosphorus soil,the soil available phosphorus in HB1treatment was 14.17%higher than that of the control.It indicated that HB1 is better to apply in the soil with low level of available P.?3?The germination rate of cucumber and pepper seeds treated with the 10⁶ times diluted P.oxalicum HB1 was 100%and 98.67%,which was 1.18 and 1.05 times of that of control,respectively.The relative seedling height and the root tolerance index were 194%,174%and 126%,105%,respectively.The germination rate of cabbage seeds treated with the 10⁷ times diluted P.oxalicum HB1 broth was 92.00%,1.01 times of that of control.The relative seedling height and the root tolerance index were 141%and 144%,respectively.This illustrated that P.oxalicum HB1 broth can promote vegetable seed germination and seedling growth.?4?The fresh weight and P accumulation amount of Chinese cabbage were increased by 21.61%and 81.64%in HB1 treatment,respectively.In soil incubation experiment,compared to the control the soil alkaline phosphatase activities and cellulase activities in HB1 treatment were increased by 10.62%and 56.41%,and the number of bacteria and fungus were increased by 109%and 96.45%in the same treatment,respectively.In summary,Penicillium oxalicum HB1 had strong ability to dissolve insoluble mineral phosphorus,which is better in soil with low available P.Moreover,Penicillium oxalicum HB1 might promot vegetables seeds germination and seedlings growth significantly.