*4.2.3 Phosphatase*

The agronomic and biotechnological importance of phosphatase is that it activates the transformation of organic P into inorganic forms of P available to plants. We have determined alkaline phosphatase since we have worked with basic soils (**Table 2**). Phosphatases are inhibited by inorganic P, the final product of their enzymatic reaction. This is due to a feedback inhibition, so phosphatases are synthesized only when available P is deficient.

In our study, no statistical differences between treatments were appreciated in this enzyme activity. This indicates that the addition to the soils of polyphenol products does not change the phosphorous cycle in the soil. Some differences in this enzyme activity were noted throughout the experimental period, greater phosphatase activity being detected at the start than at the end of the experiment. This fact could be due to P mobilization from organic to inorganic forms, in order to make it available to plants. The P cycle, studied by phosphomonoesterase activity, seems not to be affected by the polyphenol addition to the soil since little differences were observed as regards phosphatase activity between the soils treated with polyphenols


**Table 2.** *Evolution of soil alkaline phosphatase activity in kiwi soils (initial, T0, and final Tf).* and the control. Anyway, a slight increase in phosphatase activity was observed when polyphenols were introduced into the soil.

A negative effect on soil phosphatase was observed when CuSO4 is used as pesticide. It indicates that this conventional treatment can affect to P cycle in the soil.

#### *4.2.4 β-Glucosidase*

β-Glucosidase is a hydrolase which intervenes in the C cycle, acting especially in the hydrolysis of the β-glucoside bonds of long carbohydrate chains. The hydrolysis of these substrates plays an important role in the attainment of energy from the soil by microorganisms.

C cycle linked to β-glucosidase activity was not affected by the utilization of polyphenols, as shown in **Table 3**. The activity of this enzyme did not change with time in a significant way, similar activity values being observed at the start and end of the experimental period. Both polyphenols directly (form A and B and also the Cu salt introduction in soil) and their impact on the soil biota do not affect the carbon cycle.

Urease activity. Urease catalyzes the hydrolysis of urea or ureic-type substrate to give carbon dioxide and ammonia as reaction products. This term includes all those hydrolases capable of acting on the C-N (non-peptide) bonds of linear amides. They are extracellular enzymes.

At the start of the experiment, some changes in urease activity were observed in the soils treated with polyphenols with respect to the control (**Table 4**). This is indicative that the N cycle is influenced by polyphenols. The soils treated with CuSO4 showed the lowest values of urease activity; it could be due to the heavy metal incidence (Cu) or to the increase of soil salinity. At the end of the experiment, urease activity values were also lower when CuSO4 was used, but the differences were not statistically significant. For this reason, we can say that the microbial populations that synthesize urease do not undergo to experiment changes, and consequently, the N cycle does not show difference between soils.

D-hydrogenase. The biological oxidation of organic compounds occurs by means of dehydrogenation processes, in which intracellular enzymes called dehydrogenases take part. The dehydrogenation activity in soils is determined by different dehydrogenase systems, which are characterized by their high substrate specificity. All these systems are an integral part of the microorganisms; indeed, dehydrogenase activity has been proposed as an indicator of soil microbiological activity and biomass.



**91**

*Hydrolysable Tannins in Agriculture*

**Urease (μg INTF h<sup>−</sup><sup>1</sup>**

**Table 4.**

**Table 5.**

activity is noted (**Table 5**).

**Acknowledgements**

*DOI: http://dx.doi.org/10.5772/intechopen.86610*

 **g<sup>−</sup><sup>1</sup>**

**D-hydrogenase activity (μg INTF h<sup>−</sup><sup>1</sup>**

*Evolution of soil urease activity in kiwi soils (initial, T0, and final Tf).*

 **g<sup>−</sup><sup>1</sup>**

*Evolution of soil d-hydrogenase activity in kiwi soils (initial, T0, and final Tf).*

experiment showed no changes for this oxidoreductase enzyme. Only at the end of the experiment, the soils treated with CuSO4 showed a decrease in the activity of this enzyme. This different behavior between the start and the end of the experiment could be due to the fact that at the start of the experiment, the Cu salt has no time to act, and some more time needed to the effect of the salt on the enzyme

Control− 1.619 a 5.355 b Control+ 1.595 a 5.147 b CuSO4− 1.391 a 2.972 a CuSO4+ 1.559 a 4.719 b Form 1 1.174 a 5.274 b Form 2 1.487 a 5.380 b *The same letter for each parameter indicates no significant differences between treatments (Tuckey's method, p < 0.05).*

 **soil) T0 Tf**

 **soil) T0 Tf**

Control− 0.200 b 0.931 a Control+ 0.246 c 0.945 a CuSO4− 0.141 a 0.758 a CuSO4+ 0.180 ab 0.726a Form 1 0.364 d 1.008 a Form 2 0.329 d 0.806 a *The same letter for each parameter indicates no significant differences between treatments (Tuckey's method, p < 0.05).*

The main conclusion obtained from the results is that the use of polyphenols such as those prepared in the Evergreen project can be regarded as positive, since it is able to prevent bacterial diseases on crops such as kiwi. Our results indicate that the polyphenols used can be considered as biopesticides. For example, we can indicate that in agriculture, Cu is a metal widely used as a pesticide; however, the accumulation of this metal in soils can become harmful to the quality of that soil. Therefore, the possibility of having alternatives such as polyphenols, capable of acting against certain pathogenic microorganisms, has paramount agronomic and environmental interests. We think that the use of polyphenols should be studied at the level of management. The application of these compounds (the time of application if application should be repeated, if they can be used as preventive treatment,

The Authors are grateful for financial support for publishing this chapter to

etc.) should be studied, particularly for soil biological properties.

Saviolife Co. of Saviola Holding Group, Viadana (Italy).

**Table 3.** *Evolution of soil β-glucosidase activity in kiwi soils (initial, T0, and final Tf).*


**Table 4.**

*Tannins - Structural Properties, Biological Properties and Current Knowledge*

when polyphenols were introduced into the soil.

*4.2.4 β-Glucosidase*

by microorganisms.

carbon cycle.

biomass.

They are extracellular enzymes.

**β-glucosidase activity (μmol PNF h<sup>−</sup><sup>1</sup>**

and the control. Anyway, a slight increase in phosphatase activity was observed

A negative effect on soil phosphatase was observed when CuSO4 is used as pesticide. It indicates that this conventional treatment can affect to P cycle in the soil.

β-Glucosidase is a hydrolase which intervenes in the C cycle, acting especially in the hydrolysis of the β-glucoside bonds of long carbohydrate chains. The hydrolysis of these substrates plays an important role in the attainment of energy from the soil

C cycle linked to β-glucosidase activity was not affected by the utilization of polyphenols, as shown in **Table 3**. The activity of this enzyme did not change with time in a significant way, similar activity values being observed at the start and end of the experimental period. Both polyphenols directly (form A and B and also the Cu salt introduction in soil) and their impact on the soil biota do not affect the

Urease activity. Urease catalyzes the hydrolysis of urea or ureic-type substrate to give carbon dioxide and ammonia as reaction products. This term includes all those hydrolases capable of acting on the C-N (non-peptide) bonds of linear amides.

At the start of the experiment, some changes in urease activity were observed in the soils treated with polyphenols with respect to the control (**Table 4**). This is indicative that the N cycle is influenced by polyphenols. The soils treated with CuSO4 showed the lowest values of urease activity; it could be due to the heavy metal incidence (Cu) or to the increase of soil salinity. At the end of the experiment, urease activity values were also lower when CuSO4 was used, but the differences were not statistically significant. For this reason, we can say that the microbial populations that synthesize urease do not undergo to experiment changes, and

D-hydrogenase. The biological oxidation of organic compounds occurs by means

of dehydrogenation processes, in which intracellular enzymes called dehydrogenases take part. The dehydrogenation activity in soils is determined by different dehydrogenase systems, which are characterized by their high substrate specificity. All these systems are an integral part of the microorganisms; indeed, dehydrogenase activity has been proposed as an indicator of soil microbiological activity and

Dehydrogenase activity is intracellular and detects the set of cells capable of being activated against various situations; soil samples toward the initial of the

Control− 0.480 a 0.524 a Control + 0.527 a 0.531 a CuSO4− 0.527 a 0.475 a CuSO4+ 0.563 a 0.472 a Form 1 0.544 a 0.620 a Form 2 0.549 a 0.573 a *The same letter for each parameter indicates no significant differences between treatments (Tuckey's method, p < 0.05).*

 **soil) T0 Tf**

consequently, the N cycle does not show difference between soils.

 **g<sup>−</sup><sup>1</sup>**

*Evolution of soil β-glucosidase activity in kiwi soils (initial, T0, and final Tf).*

**90**

**Table 3.**

*Evolution of soil urease activity in kiwi soils (initial, T0, and final Tf).*


#### **Table 5.**

*Evolution of soil d-hydrogenase activity in kiwi soils (initial, T0, and final Tf).*

experiment showed no changes for this oxidoreductase enzyme. Only at the end of the experiment, the soils treated with CuSO4 showed a decrease in the activity of this enzyme. This different behavior between the start and the end of the experiment could be due to the fact that at the start of the experiment, the Cu salt has no time to act, and some more time needed to the effect of the salt on the enzyme activity is noted (**Table 5**).

The main conclusion obtained from the results is that the use of polyphenols such as those prepared in the Evergreen project can be regarded as positive, since it is able to prevent bacterial diseases on crops such as kiwi. Our results indicate that the polyphenols used can be considered as biopesticides. For example, we can indicate that in agriculture, Cu is a metal widely used as a pesticide; however, the accumulation of this metal in soils can become harmful to the quality of that soil. Therefore, the possibility of having alternatives such as polyphenols, capable of acting against certain pathogenic microorganisms, has paramount agronomic and environmental interests. We think that the use of polyphenols should be studied at the level of management. The application of these compounds (the time of application if application should be repeated, if they can be used as preventive treatment, etc.) should be studied, particularly for soil biological properties.

#### **Acknowledgements**

The Authors are grateful for financial support for publishing this chapter to Saviolife Co. of Saviola Holding Group, Viadana (Italy).

*Tannins - Structural Properties, Biological Properties and Current Knowledge*
