EFFECT OF SOIL FATIGUE PREVENTION METHODS ON MICROBIOLOGICAL SOIL STATUS IN REPLANTED APPLE TREE ORCHARD. PART II. NUMBER OF BACTERIA

Krzysztof Rutkowski¹, Eugeniusz Pacholak¹, Zofia Zydlik^2
1 Department of Pomology, University of Agriculture in Poznan, Poland
² Department of Pomology, Poznań University of Life Sciences, Poland

ABSTRACT

The object of the investigation were bacteria in the soil in diversified conditions of orchard irrigation and with the use of different methods of soil disease prevention. Samples for the estimation of the number of bacteria were taken in spring and autumn.

During the study the following results were obtained: the total number of bacteria in the replanted orchard was lower than in the soil where apple trees had not been cultivated before.

The irrigation did not increase of bacteria population in the soil, whereas the ammonium phosphate increased it. On the number of bacteria in the soil had influence also the application of the Alliette 80 WP and ammonia phosphate which decreased Azotobacter number in comparison with the control. The use of ammonia phosphate increased the number of Azospirillum in soil.

Key words: apple, replant soil, bacteria.

INTRODUCTION

The phenomenon of dynamic unbalance resulting from the growing of the same species for many years on the same area is defined by the term of soil fatigue. Its symptoms are particularly visible during a repeated planting of the same plant species. This problem may be caused by harmful biotic and abiotic factors which had accumulated in the soil during earlier cultures [10, 11]. Such situation leads to poor growth, delay in the start of fructification and in extreme cases to the death of trees. Soil microorganisms, such as bacteria, fungi or actinomycetes are mentioned as the main causes of replantation disease [12, 13]. Microbiological activity of bacteria depends on soil and climatic conditions [1, 5].

The objective of studies carried out in 2000-2004 was the estimation of effect of irrigation and soil fatigue preventing methods on the number of bacteria and nitric bacteria (Azotobacter and Azospirillum) in the soil of replanted orchard.

MATERIAL AND METHODS

This paper presents the second part of results of the microbiological activity of soil depending on the moisture and the applied treatments preventing soil fatigue. This part of work contains results referring to the general number of bacteria and to the activity of Azotobacter and Azospirillum. The presented results include the period of 2000-2004. A detailed description of the studied material and irrigation combinations as well as replantation disease prevention methods were presented in Part I of this work.

Soil samples were collected in autumn and spring of 2000-2004.

spring	autumn
11.05.2000	19.09.2000
13.05.2001	15.09.2001
09.05.2002	13.09.2002
12.05.2003	13.09.2003
10.05.2004	14.09.2004

The number of microorganisms was estimated in fresh soil and the following data were identified:

• total number of bacteria on units 2% agar medium of soil extract made of 1 kg of soil with an addition of 200 mg K₂HPO₄ per l liter of extract after 14 days of incubation,

• Azotobacter estimation was made according to the method elaborated by Fenglerowa [3], after 4 days of incubation at 28°C,

• Azospirillum on semi-liquid nourishing substance NFb as titer according to Döbereiner [2].

Inoculations were made in 5 replications and the number of microorganisms was calculated per l g of soil fresh mass.

In order to present the number of microorganisms in dynamic approach, we have applied the mean values from the years 1998-1999 [8] and from the soil not used earlier for fruit-growing purposes.

The obtained results were subject to multifactorial analysis of variance and the differences between the particular mean values were estimated using Duncan’s test at the level of a = 0.05. Correlation coefficients for soil moisture, soil pH and bacteria number were calculated by linear correlation coefficient.

RESULTS

The number of bacteria in replanted apple orchard depended on: the term of sampling, level of soil moisture and the applied methods of soil fatigue prevention.

Total number of bacteria. The total number of bacteria depended on the term of sampling. In 2000-2004, a greater number of bacteria was recorded than in the period 2002-2003 where an insignificant drop in the number of microorganisms was recorded. Comparison of values obtained with those from the initial period in the years 1998-1999 showed a tendency of bacteria decrease. However, in the last year of studies, a significant increase of total bacteria number in soil after replantation was found. It must be noted that in the soil not used for fruit-growing purposes, the bacteria number for the period 2000-2004 was higher than in the soil after replantation, but it was not a statistically significant number (fig. 1).

Fig. 1. Effect of sampling date on numbers of bacteria in the soil in 2000-2004 (in 1 g of soil fresh weight)

Irrigation in the years 2000-2004 had no significant effect on the total number of bacteria. Only the application of irrigation on the level of -0.01 MPa of soil water potential increased the number of bacteria in soil (fig. 2).

Fig. 2. Effect of irrigation on numbers of bacteria in the soil in 2000-2004 (in 1 g of soil fresh weight) W0 – without irrigation; W1 – moisture level -0.03 MPa; W2 – moisture level -0.01 Mpa

The applied methods of soil fatigue prevention modified the total number of bacteria in soil. It must be stressed that virgin soil was characterized by the highest total number of bacteria. Also the application of ammonium phosphate significantly increased that number. An application of fungicide, peat or Temik 10 G did not have any significant effect but in these combination the number of bacteria was lower than in control soil (fig. 3).

Fig. 3. Effect of prevention methods replant disease on numbers of bacteria in the soil in 2000-2004 (in 1 g of soil fresh weight)

Azotobacter. The number of Azotobacter depended on the term of sampling, the irrigation level and on the applied soil fatigue prevention methods.

In 2000-2001, the number of nitric bacteria Azotobacter was lower than in the first period after the removal of old trees (1998-1999). In the successive two years, an increase of Azotobacter bacteria was found but it was not statistically significant. Only in the autumn of 2003, the number of Azotobacter bacteria was higher than in the other terms. Virgin soil, independent of the term, was characterized by the highest activity. Only in one case (autumn 2003), the mean number of Azotobacter was higher than the mean value in autumn period for virgin soil (fig. 4).

Fig. 4. Effect of sampling date on numbers of Azotobacter in the soil in 2000-2004 (in 1 g of soil fresh weight)

Soil moisture maintained at the level of -0.01 MPa caused an increase of the number of Azotobacter bacteria, while in case of irrigation absence and moderate moisture (-0.03 MPa), no positive effect on the bacteria number was found (fig. 5).

Fig. 5. Effect of irrigation on numbers of Azotobacter in the soil in 2000-2004 (in 1 g of soil fresh weight) W0 – without irrigation; W1 – moisture level -0.03 MPa; W2 – moisture level -0.01 MPa

The applied methods of replantation disease prevention exerted an effect on Azotobacter number. Nematodecidal preparation (Temik 10 G) and virgin soil had a favorable effect on the number of nitric bacteria Azotobacter. Such effect was not found when other methods of soil fatigue prevention were applied (fig. 6).

Fig. 6. Effect of prevention methods replant disease on numbers of Azotobacter in the soil in 2000-2004 (in 1 g of soil fresh weight)

Azospirillum. In the studies on Azospirillum number, it was found that the term of sampling for nitric bacteria number had an influence on the results. Contrary to the case of Azotobacter, in the first period until the year 2002, the number was maintained on a significantly higher level than in the years 2003-2004. An exception was in spring 2000, when a significantly lower number of Azospirillum was found. In the last two years, a decreased microbiological activity of the nitric bacteria Azospirillum was found (fig. 7).

Fig. 7. Effect of sampling date on numbers of Azospirillum in the soil in 2000-2004 (in 1 g of soil fresh weight)

The applied method of soil moisture maintenance had an effect on the number of Azospirillum. With the increase of moisture, the number of nitric bacteria in soil increased as well (fig. 8).

Fig. 8. Effect of irrigation on numbers of Azospirillum in the soil in 2000-2004 (in 1 g of soil fresh weight) W0 – without irrigation; W1 – moisture level -0.03 MPa; W2 – moisture level -0.01 MPa

Combination with replantation disease prevention significantly modified the microbiological activity of Azospirillum. The application of Aliette 80 WP, Temik 10 G, or peat decreased the number of Azospirillum. Only in the combination with ammonium phosphate, the nitric bacteria number was higher than in control combination. The highest number was recorded in virgin soil (fig. 9).

Fig. 9. Effect of prevention methods replant disease on numbers of Azospirillum in the soil in 2000-2004 (in 1 g soil fresh weight)

Table 1. Coefficients of linear correlation between abiotic factors and Bacteria number in the soil

Factor	Date	Total bacteria	Azotobacter	Azospirillum
Soil moisture	spring	0.3075	0.5160	-
	autumn	0.3491	-	-
Soil pH	spring	-	0.5979	-
	autumn	0.4093	-	-

Indices of linear correlation indicate a dependence between the total number of bacteria and the soil pH in the autumn (tab. 1). The number of Azotobacter was positively correlated in the spring term with soil pH and soil moisture On the other hand, soil reaction and soil moisture exerted no effect on the number of Azospirillum bacteria.

DISCUSSION

Number of bacteria was connected with the intensity of irrigation. A positive effect of soil moisture was particularly visible in case of Azotobacter and Azospirillum. No such unequivocal dependence was found in the analysis of the total number of bacteria in soil. Similar results were obtained by Pacholak et al. [6], where the number of bacteria was positively correlated with the increase of moisture. The obtained results agree with the results of Gołębiowska [4] who characterized bacteria as more demanding ones regarding moisture than fungi.

Application of combinations preventing soil fatigue modified the number of nitric bacteria. Particularly the application of ammonia phosphate in case of total bacteria number and Azospirillum bacteria contributed to the increase of their number. Reduction of Azotobacter was earlier obtained by Pacholak et al. [7], where an increased mineral fertilization reduced the number of this nitric bacteria. Gołębiowska [4] called attention to the fact that the accumulation of nitrogen compounds may decrease the number of bacteria. Schlegel [9] stressed the favorable effect of phosphorus on the development of nitric bacteria. However, only in case of Azospirillum, a stimulating action of ammonia phosphate was found, while phosphorus impeded the development of Azotobacter in that experiment.

CONCLUSIONS

Analysis of the microbiological soil status on the basis of the number of Azospirillum and Azotobacter bacteria permits to draw the following conclusions:

1. Soil from the studied replanted orchard was characterized by a smaller number of bacteria than a virgin soil.

2. Soil from the studied replanted orchard was characterized by a smaller number of bacteria than a virgin soil.

3. Irrigation had no significant effect on the total number of bacteria but increased of Azotobacter population.

4. The application of ammonia phosphate increased the total bacteria number.

5. The number of Azospirillum increased with the increasing soil moisture.

6. The use of ammonia phosphate increased the number of Azospirillum in soil.

REFERENCES

1. Čatska V., 1993. Fruit tree replant problem and microbial antagonism in soil. Acta Hort. 324, 23-34.

2. Döbereiner J., 1980. Forage grasses and grain crops. [In:] Bergensen F.J. (red.) Methods for evaluating biological nitrogen fixation. John Wiley and Sons Ltd. Chester, New York, Toronto, 535.

3. Fenglerowa W., 1965. Simple method for counting Azotobacter in soil. Acta Mikrobiol. Pol. 14, 203.

4. Gołębiowska J., 1986. Mikrobiologia rolnicza [Agricultural microbiology]. PWRiL Warszawa [in Polish].

5. Hoestra H., 1988. General remarks on replant disease. Acta Hort. 233, 11-16.

6. Pacholak E., Rutkowski K., Sawicka., 2001. Wpływ nawadniania i sposobów zapobiegania zmęczeniu gleby na liczebnosc bakterii w warunkach zróżnicowanej wilgotnosci gleby [Effect of irrigation and soil sickness prevention methods on the number of bacteria on the different moisture of soil]. Zesz. Nauk. Inst. Sadow. i Kwiac. 9, 17-24 [in Polish].

7. Pacholak E., Zydlik Z., Sawicka A., 2004. Wpływ nawożenia i nawadniania na stan mikrobiologiczny gleby w replantowanym sadzie jabłoniowym. Cz. II Liczebnosc bakterii [Effect of fertilization and irrigation on soil microorganisms in a replanted orchard. Part II Numbers of bacteria]. Pr. Kom. Nauk Rol. i Kom. Nauk Les. PTPN 97, 307-316 (in Polish).

8. Rutkowski K., Pacholak E., Sawicka A., 2000. Ocena składu mikrobiologicznego gleby. Cz. I. Liczebnosc bakterii [Evoluation of the microbiological state of the soil under varied conditions of fertilization and irrigation in a replanted orchard. Part I. Numbers of bacteria]. Pr. Kom. Nauk Rol. i Kom. Nauk Les. PTPN 89, 175-184 [in Polish].

9. Schlegel G.H., 1996. Mikrobiologia ogólna [Microbiology]. PWN Warszawa [in Polish].

10. Sobiczewski P., 2000. Bakterie w służbie ochrony roslin przed chorobami [Using of bacteria in plant protection against diseases]. Ochrona Roslin 7, 41-43 [in Polish].

11. Szczygieł A., 1997. Choroba replantacji w sadzie (I) [Replanted disease in orchard]. Sad Nowoczesny 7, 5-6 [in Polish].

12. Utkhede R. S., Smith T.J., 1994. Biotic and abiotic causes of replant problem of fruit trees. Acta Hort. 363, 25-32.

13. Utkhede R.S., 1998. Influence of cultural practices on the growth and yield of young apple trees planted in replant disease soil. Acta Hort. 477, 27-38.

 

Accepted for print: 13.12.2006

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Krzysztof Rutkowski
Department of Pomology,
University of Agriculture in Poznan, Poland
159 Dąbrowskiego Street, 60-594 Poznan, Poland
Phone (+48 61) 848 79 48

Eugeniusz Pacholak
Department of Pomology,
University of Agriculture in Poznan, Poland
159 Dąbrowskiego Street, 60-594 Poznan, Poland
Phone (+48 61) 848 79 48

Zofia Zydlik
Department of Pomology, Poznań University of Life Sciences, Poland
ul. Dąbrowskiego 159
60-594 Poznań, Poland
email: zydlik@au.poznan.pl

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