EFFECT OF SOIL FATIGUE PREVENTION METHODS ON MICROBIOLOGICAL SOIL STATUS IN REPLANTED APPLE TREE ORCHARD. PART III. NUMBER OF FUNGI AND ACTINOMYCETES

Zofia Zydlik¹, Krzysztof Rutkowski², Eugeniusz Pacholak^2
1 Department of Pomology, Poznań University of Life Sciences, Poland
² Department of Pomology, University of Agriculture in Poznan, Poland

ABSTRACT

The objective of studies was estimation of the number of fungi and actinomycetes as relate to the methods of replant disease prevention in the conditions of diversified soil moisture. The number of fungi and actinomycetes in the soil of replanted orchard was related to the date of sampling, combination of the irrigation soil and disease prevention methods. The number of fungi and actinomycetes was different according to the date of soil sampling (spring or autumn). The applied methods of replantation disease prevention as well as irrigation had an effect on the number of fungi and actinomycetes.

Key words: apple tree, replant soil, fungi, Actinomycetes.

INTRODUCTION

Possibilities of establishing an orchard on an area which had not been utilized earlier for fruit-growing purposes, or which had a break of several years in fruit-growing use are very limited. Therefore, most frequently, orchards are replanted on areas of earlier fruit-growing localities. In such cases, one frequently can find that the growth of trees is poor or, in extreme cases, the trees waste away.

The primary factors responsible for troubles connected with tree growth in the initial period are the biotic factors [4]. From the etiological point of view of this disease, patogenic fungi play the most important role. They include the following genera: Phytophthora [14, 15], Cylindrocarpon [9], Rhizoctonia solani [7, 8], Fusarium or Pythium [12]. Particularly Pythium spp. are characterized by a high pathogenicity to apple-trees [2, 5]. Many researchers stress a high importance of Actinomycetes which causethe replantation disease.

Studies of Otto et al. [10] indicate that Actinomycetes are the main cause of poor growth of trees because they paralyse the root system. Damages of capillary root epidermis lead to disturbances in water and nutritive component uptake contributing thereby to a poorer growth and in consequence to the dying of trees [13].

The objective of the studies in the years 2000-2004 was to estimate the effect of irrigation and methods of soil fatigue prevention on the number of fungi and Actinomycetes in the soil of a replanted orchard.

MATERIAL AND METHODS

Studies on the number of fungi and Actinomycetes constitute the third part of the research work on soil fatigue in orchards. The studies include the occurrence of fungi and Actinomycetes in depending on irrigation and methods of replantation disease prevention. Experimental conditions were described in the Part I of this work.

Soil samples were collected in the years 2000-2004 in autumn and spring terms.

Samples for microbiological analyses were taken from fresh soil and the following determinations were carried out:

• fungi on Martin’s [6] nutritive solution 5 days after inoculation at 24°C,

• Actinomycetes on chitin nutritive solution according to Lingapp and Lockwood [3] 7 days after inoculation at 24°C.

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

The obtained results were subject to multifactorial analysis of variance and the significant differences between the particular mean values were evaluated using Duncan’s test at the level of a= 0.05 in Statistica 7.1 program.

RESULTS

In the period of many-year studies carried out in a replanted orchard, it was found that there was a significant effect of sampling terms, soil moisture and methods of soil fatigue prevention on the number of fungi and actinomycetes.

Fungi. The number of fungi depended on the term of sampling. In 2000 and 2001 an increase of fungi number was recorded in comparison with the first period of studies in the years 1998-1999. However, such tendency did not continue in the successive years. In 2002, there followed a significant drop of the activity of fungi from the replanted orchard. In the successive four terms, the number of fungi increased (2003 and 2004). In spring 2002 the fungi number was significantly higher than in autumn, however, in other seasons such regularity was not observed (fig. 1).

Irrigation exerted an essential effect on the number of fungi. With the increase of irrigation intensity, the number of fungi decreased. Both the irrigation at the level of -0.03 MPa and at -0.01 MPa of water potential decreased significantly the number of fungi in the soil (fig. 2).

The applied methods of soil fatigue prevention had a significant effect on the number of fungi. The use of ammonia phosphate and a nematodecidal preparation (Temik 10 G) increased the fungi number. Fungicidal preparation (Aliette 80 WP) did not contribute to the reduction of fungi in comparison with control combination (fig. 3).

Actinomycetes. Microbiological activity of Actinomycetes was closely related with the sampling term and with the methods of soil fatigue prevention.

Comparison of actinomycetes number in the first period after replantation (1998-1999) revealed a decrease of Actinomycetes activity in the successive years 2000-2003. In 2004, both in the spring term and in the autumn term, the number of Actinomycetes was significantly higher than in the previous years (fig. 4).

Irrigation did not have any significant effect on the number of Actinomycetes. An increase of Actinomycetes number was found when irrigation was applied, but the differences were not statistically significant (fig 5).

The applied methods of soil fatigue prevention had an effect on the number of Actinomycetes. Application of ammonia phosphate significantly contributed to the decrease of the number of actinomycetes. A drop of activity was visible when the preparation Aliette 80 WP and Temik 10 G were applied. Virgin soil showed a greater activity than control combination (fig. 6).

Statistical analysis of the effect of irrigation on soil pH showed a close dependence between irrigation intensity and soil reaction. Proportionally to the increasing irrigation doses, soil pH increased as well (fig. 7).

DISCUSSION

Application of irrigation decreased the number of fungi. Such dependence was not observed in case of actinomycetes where their number increased in comparison with control combination. It must be noted that with irrigation intensity, there increased the ph of soil (fig. 7), deteriorating the developmental conditions. Gołębiowska et al. [1] stressed that with the increased concentration of hydrogen ions, the development of microorganisms may be impeded.

There was no such unequivocal reaction of Acinomycetes to the increase of irrigation intensity. It started to be seen under the effect of irrigation, but when the soil moisture was maintained at the level of -0.01 MPa, the number was lower than at -0.03 MPa. The obtained results agree with the earlier results of Zydlik and Pacholak [16].

The applied methods of soil fatigue prevention modified the number of fungi. The greatest effect on the fungi number was exerted by the application of ammonia phosphate and the nematodecidal preparation Temik 10 G. Earlier studies of Pacholak et al. [11] showed the greatest activity of fungi in the combination with virgin soil. Ammonia phosphate had previously an effect on fungi activity, but in a lesser degree.

Actinomycetes number depended on the methods of soil fatigue prevention. Peat and soil replacement increased the number of actinomycetes. On the other hand, the application of nematodecidal preparation or ammonia phosphate decreased the number. Earlier studies of Pacholak et al. [11] partially showed similar results where virgin soil was characterized by a higher number of Actinomycetes and peat had no essential effect on the activity of Actinomycetes. The application of fungicidal preparation Aliette 80 WP and ammonia phosphate decreased the number of Actinomycetes in soil. Earlier results of Pacholak et al. [11] did not support this dependence. Both the fungicide and ammonia phosphate increased the number of Actinomycetes.

CONCLUSIONS

Microbiological analysis of soil on the basis of the number of fungi and Actinomycetes showed the effect of the term, irrigation and the methods of soil fatigue prevention and it permits to draw the following conclusions:

1. Term of sampling had a significant effect on the number of fungi and Actinomycetes.

2. Irrigation had an effect on the increase of Actinomycetes number and it decreased the number of fungi.

3. The applied methods of replantation disease prevention increased the number of fungi and Actinomycetes.

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Accepted for print: 13.12.2006

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