Isolation and Characterization of Rhizosphere Bacteria Capable to Activate Phosphorus in the Alkaline Soil.pdf

1、Phosphorus (P) is a major constraint on agricultural productivity low availability in alkaline soils.Although soils are rich in total P, yet it is unavailable to plants and is considered as a limiting factor of plant gro

2、wth.Application of super phosphate fertilizers is essentially required to maximize plant growth.Generally, P use efficiency of applied fertilizer is low because of the formation of insoluble complexes with soil colloids.

3、P is sequestered mostly through the mechanisms of precipitation and adsorption on Ca, Fe, and Al etc.Although a large amount of the total P in soils is present as organic form; however, the sole form of P assimilated by

4、microorganisms and plants is mineral orthophosphate ions.Soil microorganisms are the major source of such enzymes.Besides the conventional methods of mineral phosphate fertilization, microbial P-solubilization may help t

5、o improve the availability of phosphates in P-deficient soils.Use of phosphorus solubilizing bacteria (PSB) as inoculants directly to soil increased P uptake by releasing organic acids,these microbes could enhance P acqu

6、isition by plant indirectly through increased plant growth.This study was conducted to isolate phosphorus solubilizing bacteria PSB from the Chinese soil rhizosphere and numbers of treatments were tested on tomato and wh

7、eat in addition to use superphosphate fertilizer (SPF) to manage soil deficient in available P.The study was objective to evaluate the response of PSB activity on growth of tomato and wheat in invitro and pots experiment

8、 at Yangzhou University, Jiangsu province, China, during the seasons of tomato and wheat respectively.The objectives of this research were 1.Isolation and characterization of the efficient phosphate solubilizing bacteria

9、 from Chinese soil rhizosphere 2.Enhancement of fertilizer value of superphosphate fertilizer values through phosphate solubilizing in high soil pH 3.Study the ability of bacteria to decrease a soil pH.The first and two

10、experiments design were completely randomized design including two factors, inoculation of PSB with SPF and without fertilizer.Every experiment was conducted with five treatments and three replicates were used in pots ex

11、periment follows: uninoculated soil control, soil mixed with isolate PSB (5 × 106cfu), soilmixed with PSB and 25％ amount of superphosphate fertilizer (0.75g/pot), soil mixed with PSB and 50％ amount of superphosphate fert

12、ilizer (1.5g/pot), and soil mixed with recommended dose of superphosphate (3g /pot).Five treatments and three replicates were used in tomato pots experiment without fertilizers were following:uninoculated Soil control T0

13、, Soil mixed with isolate T1 (5×106cfu), Soil mixed with isolate T2 (6×106cfu), Soil mixed with isolate T3 (7.1×l06cfu), Soil mixed with isolate T4 (8.2× 106cfu).16S rDNA sequence analysis was carried out and the strain

14、was showed close proximity with Burkholderia oklahomensis C6786 (100％) under the accession number (CP009556.1).Research result indicated that during preliminary screening approach under invitro conditions, the bacterium

15、was changed the initial pH during all the incubation time after 7, 14, and 21 days, and the pH was decreased from 8 to 7 at the first week from 9 to 6.9 in second week and 9 to 7.1 in last week.The inoculation was showed

16、 maximum P solubilization at pH 9, which ranged from solubilized TriCalcium Phosphate (TCP) at all initial pH values in a liquid medium,with the difference being observed for phosphorus among the difference pH values of

17、the medium.using inoculation of selected bacterium with different levels of SPF on tomato plant were showed that the inoculation of PSB with 25％ SPF was found to be the best inoculation increased the fresh weight than un

18、inoculated control and among the PSB with 25％ SPF was the most effective to increase the fresh weight than uninoculated control.The levels of 50％ SPF and 100％ SPF were the next effective to increase the fresh weight than

19、 control.Inoculation of only PSB cells was obtained the maximum increasing plant height was recorded in plants inoculated with T4 (8.2× 106)in all growth stage.Maximum stem diameter was recorded in plants inoculated with

20、 T3 (7.1× 106 CFU) after 30 days.The best result was recorded in T3.Inoculation of PSB was recorded significantly higher fresh weight on T1 (5×106 CFU) when compared each treatment with the uninoculated control.The T3 (7

21、.1×106 CFU)showed higher P available content.Inoculation with PSB caused a significant increase in available phosphorus in soil in all the treatments more than uninoculated control.Inoculation with PSB isolate also propo

22、sed enhanced P uptake by wheat plant and available P in soil higher than uninoculated control respectively.This study recommended that bacteria could be more effective in tomato plant than wheat to improve crop growth an