**5.2 Effects on the nutrient supply in cucumber cultivation using biostimulators**

Cucumber plants were grown in substrate culture using containers (volume 8 L) filled with perlite. The perlite from Slovakia had an average dry density of 120 kg/ m<sup>3</sup> and a grain size between 0.6 and 1.5 mm diameter, with a pore volume of 84% v/ v, water capacity 45% v/v and air capacity of 39%. Investigations with the organic biostimulators were undertaken regarding the effects:


Nutrient solution was calculated with the HYDROFER program, considering the water quality and the target value during cucumber plant growth, in order to adjust the amounts of fertilizers, salts and acids required [13]. The target values for this experiment was 170 ppm N, 50 ppm P, 260 ppm K, 150 ppm Ca, 60 ppm Mg, 3 ppm Fe, S 80 ppm, the HCO3 content was adjusted by 90 ppm. Nutrient solution was applied using trickle irrigation 2 to 4 times a day 250 ml per irrigation cycle in period of 12–15 min.

#### *5.2.1 Effects of biostimulators on the salt concentration (EC) in the rhizosphere*

Strong fluctuation of the salt concentration (EC) can lead to an imbalance of nutrient supply in hydroponic system and can decrease plant growth and yield as it was shown for tomatoes [14]. The negative effects on cucumber plant growth if the EC values (EC 8 mS cm<sup>1</sup> ) is very high could be positively influenced by application of humates and *B. subtilis* (FZB24®) separately or combined. This is probably an effect by the encouraging of root growth. Lactate (LACTOFOL) application had no effect in this regard. Even if the nutrient solution has the appropriate salt concentration (EC), in substrate culture, with increasing duration of the cucumber cultivation there could be an accumulation of salts mainly based on those nutrients, which are not necessary in the amount as applicate. [15]. This could lead to salt stress and reduced yield in crops like cucumber. Application of Humate and/or *Bacillus subtilis* FZB24® reduced this salt accumulation (**Figure 2**).

sustainable culture of the bacteria and adsorption of the Humate on the perlite. The

*Growth Promoting and Stabilizing of Cucumber Plants Cultivated in Soilless Cultivation…*

biostimulators grew more vigorously and had in tendency a higher yield (**Table 8**).

For plants, which are adopted on lower pH, like tomatoes and beans [14, 16] it is well known that, pH values higher than 5.7 in substrates can disturb plant growth. In some growing media as rockwool or perlite, the initial pH is higher than 6.5. To change the pH by additional preparation of the substrates before using with a nutrient solution having lower pH takes time and is sometimes difficult. During the cultivation of the plants to change the pH value is also not always successful. Therefore, different treatments with biostimulators were tested. Application of Lactate stimulated root growth and shoot development even at pH 7.5. In general,

increase of EC from 1.5 to 3.6 was not so strong, but plants treated with

pH values affect the nutrient availability and uptake, in particular of

The nutrient uptake was positive influenced even the pH was higher than

micronutrients. As recorded in experiments with cucumber [15], the pH of substrates in soilless culture systems, changed with the duration of cultivation

(**Figure 3**) and declined in the control to 5.2. The pH of the substrates treated with biostimulators was more stable, especially if *B. subtilis* FZB24® was added to the nutrient solution as single component or in combination with the other compounds.

The evaluation of growth parameters of cucumber plants showed if they were treated with biostimulators then shoot and total leaf weight was significant higher than non-treated plants especially if the plants treated with all three components (**Table 8**). For the mean number of fruits harvested per plant in this short-term experiment, no significant differences between the variants, control and different

*Effect of biostimulators (0.1% lactate, 0.01% K-Humate, 0.2%* B. subtilis *FZB24®) on pH development in the*

*5.2.2 Effects on pH values in the rhizosphere*

*DOI: http://dx.doi.org/10.5772/intechopen.96536*

*5.2.3 Effects on growth of cucumber plants*

treatments with biostimulators.

*substrate during cultivation of cucumber [15].*

recommend.

**Figure 3.**

**77**

K-Humate showed the highest efficiency for EC stabilization this Humate was even more effective than *B. subtilis* (FZB24®). The mixture of all three compounds, however, was as effective as Humate alone and stabilized the salt concentration (EC) at about a value of 2 EC. The stabilizing effect of the salt concentration could be maintained over weeks after the last application indicating that there could be a

#### **Figure 2.**

*Effect of biostimulators (0.1% lactate, 0.01% K-Humate, 0.2%* B. subtilis *FZB24®) on EC development in the substrate during cultivation of cucumber [15].*


#### **Table 8.**

*Growth parameters of cucumber plants treated or non-treated with biostimulators [15].*

*Growth Promoting and Stabilizing of Cucumber Plants Cultivated in Soilless Cultivation… DOI: http://dx.doi.org/10.5772/intechopen.96536*

sustainable culture of the bacteria and adsorption of the Humate on the perlite. The increase of EC from 1.5 to 3.6 was not so strong, but plants treated with biostimulators grew more vigorously and had in tendency a higher yield (**Table 8**).

#### *5.2.2 Effects on pH values in the rhizosphere*

*5.2.1 Effects of biostimulators on the salt concentration (EC) in the rhizosphere*

*Cucumber Economic Values and Its Cultivation and Breeding*

EC values (EC 8 mS cm<sup>1</sup>

**Figure 2.**

*substrate during cultivation of cucumber [15].*

K-Humate, Lactate, B.s

FZB24®

**Table 8.**

**76**

**Variants Shoot weight**

Strong fluctuation of the salt concentration (EC) can lead to an imbalance of nutrient supply in hydroponic system and can decrease plant growth and yield as it was shown for tomatoes [14]. The negative effects on cucumber plant growth if the

of humates and *B. subtilis* (FZB24®) separately or combined. This is probably an effect by the encouraging of root growth. Lactate (LACTOFOL) application had no effect in this regard. Even if the nutrient solution has the appropriate salt concentration (EC), in substrate culture, with increasing duration of the cucumber cultivation there could be an accumulation of salts mainly based on those nutrients, which are not necessary in the amount as applicate. [15]. This could lead to salt stress and reduced yield in crops like cucumber. Application of Humate and/or

K-Humate showed the highest efficiency for EC stabilization this Humate was even more effective than *B. subtilis* (FZB24®). The mixture of all three compounds, however, was as effective as Humate alone and stabilized the salt concentration (EC) at about a value of 2 EC. The stabilizing effect of the salt concentration could be maintained over weeks after the last application indicating that there could be a

*Effect of biostimulators (0.1% lactate, 0.01% K-Humate, 0.2%* B. subtilis *FZB24®) on EC development in the*

**Leaf weight (g plant<sup>1</sup> )**

911.83 a 235.33 a 7.4 ns

**Fruits per plant**

**(g plant<sup>1</sup> )**

*Different letters indicate significant differences, LSD, p* ≤ *0.05); ns = non-significant.*

*Growth parameters of cucumber plants treated or non-treated with biostimulators [15].*

Control 676.00 d 172.33 c 7.0 ns 0.1% Lactate 817.50 bc 203.00 b 10.0 ns 0.01% K-Humate 776.33 c 203.67 b 7.8 ns 0.2% B.s FZB24® 839.33 b 202.83 b 10.4 ns

*Bacillus subtilis* FZB24® reduced this salt accumulation (**Figure 2**).

) is very high could be positively influenced by application

For plants, which are adopted on lower pH, like tomatoes and beans [14, 16] it is well known that, pH values higher than 5.7 in substrates can disturb plant growth. In some growing media as rockwool or perlite, the initial pH is higher than 6.5. To change the pH by additional preparation of the substrates before using with a nutrient solution having lower pH takes time and is sometimes difficult. During the cultivation of the plants to change the pH value is also not always successful. Therefore, different treatments with biostimulators were tested. Application of Lactate stimulated root growth and shoot development even at pH 7.5. In general, pH values affect the nutrient availability and uptake, in particular of micronutrients. As recorded in experiments with cucumber [15], the pH of substrates in soilless culture systems, changed with the duration of cultivation (**Figure 3**) and declined in the control to 5.2. The pH of the substrates treated with biostimulators was more stable, especially if *B. subtilis* FZB24® was added to the nutrient solution as single component or in combination with the other compounds. The nutrient uptake was positive influenced even the pH was higher than recommend.

#### *5.2.3 Effects on growth of cucumber plants*

The evaluation of growth parameters of cucumber plants showed if they were treated with biostimulators then shoot and total leaf weight was significant higher than non-treated plants especially if the plants treated with all three components (**Table 8**). For the mean number of fruits harvested per plant in this short-term experiment, no significant differences between the variants, control and different treatments with biostimulators.

#### **Figure 3.**

*Effect of biostimulators (0.1% lactate, 0.01% K-Humate, 0.2%* B. subtilis *FZB24®) on pH development in the substrate during cultivation of cucumber [15].*

It can be assumed that the EC and pH stabilizing effects of the biostimulators contributed that better development of the plant, in particular if all three components are used together.

### **5.3 Effect of biostimulators and their application method on growing of cucumber plants**

The bio-substances and Bacillus subtilis used as biostimulators had beneficial effects on plant growth in several experiments, also in stress situations, as inappropriate EC and pH value. The biostimulators were used in single applications or as a mix in the rhizosphere, but the lactate was used at the beginning as foliar-fertilizer [14]. Therefore, it came to the thought to use the biostimulators to the root zone and on the leaves. The aim was to investigated which treatment is the most effective one.

Experimental design is shown in **Table 9**, eight different treatments were compared with the control.

K-Humate (Fa. Humintech), Lactate (Fa. ECOFOL, **Table 2**) and *B. subtilis* FZB24® (Fa. ABITEP GmbH) was applied on leaves or on the substrate used in this experiment. Quantity and concentration of applied substances were deduces from previous experience [14].

> induced in each case to a higher fresh matter compared to the control. If the Biostimulators were applied on the leaves, the effect on shoot fresh matter was not as strong in comparison to the application in the root zone. When *B. subtilis*

*Growth Promoting and Stabilizing of Cucumber Plants Cultivated in Soilless Cultivation…*

*DOI: http://dx.doi.org/10.5772/intechopen.96536*

the effect on the root growth was much stronger than on the shoot growth.

leaves an inhibiting effect for cucumber plant growth.

**Figure 4.**

**Figure 5.**

**79**

(FZB24®) was used, the fresh mass of the shoot was even lower. It can be stated, if the combined biostimulator with all substances was applied the effect was different if applied over the roots was a stimulating effect visible, whereas if applied over the

*Fresh matter of leaves and shoots of cucumber plants after biostimulator application (lactate, K-Humate, B.subtilis BS) on leaves and roots respectively [17]. Different letters indicate significant differences (LSD, P = 0.05).*

Comparing the effect of the treatments, also the quality of shoots and leaves seems to be different and effects on the weakness against fungi's could be expected. This effect was also found in experiments with Water spinach [18] however, in these experiments

Comparing the ratio between shoot and leaf fresh matter (**Figure 5**) there are no significant differences between all variants, but it seems the leaf application stronger stimulateed the leaf growth than shoot growth resulting in a lower ratio.

*Effect of application biostimulators (lactate, K-Humate, FZB24®) on leaves and roots respectively on the ratio*

*of shoots and leaf biomass after finishing the experiment [17]. No significant differences.*

Cucumber plants were planted and cultivated in containers (volume of 7–8 liters) filled with Perlite. Nutrient solution was calculated following the HYDROFER program [13] to adjust the amounts of fertilizers, salts and acids required according the values (170 ppm N, 50 ppm P, 260 ppm K, 150 ppm Ca, 60 ppm Mg, 3 ppm Fe, 90 ppm HCO3). By trickle irrigation 2 to 4 times a day 250 ml per irrigation cycle was applied in period of 12–15 min.

Additional the plants were treated with one of the treatments, 20 ml per container and plant, three times in weekly intervals in following development stages: the first treatment in 5–6 leafs stage; second in 7–8 leafs stage; third in 9–10 leafs stage. For the variant -Leaf application- the different treatments were sprayed on the surface of leafs. In case of variant -Root application- the different treatments were given to the substrate and thereby into the rhizosphere of the plants, in the same amount and frequency.

#### *5.3.1 Shoot development*

The application of biostimulators three times in the growing stage (week 4, 5, and 6) affected development and yield of cucumber plants. The application of the biostimulators stimulated the growth represented by a higher fresh matter of shoots and leaves in most variants (**Figure 4**). Obviously, the location of application was important for the effect of the biostimulators. The application to the root zone


#### **Table 9.**

*Concentrations and application patterns of biostimulators used in the experiment [17].*

*Growth Promoting and Stabilizing of Cucumber Plants Cultivated in Soilless Cultivation… DOI: http://dx.doi.org/10.5772/intechopen.96536*

#### **Figure 4.**

It can be assumed that the EC and pH stabilizing effects of the biostimulators contributed that better development of the plant, in particular if all three compo-

**5.3 Effect of biostimulators and their application method on growing of**

*Cucumber Economic Values and Its Cultivation and Breeding*

The bio-substances and Bacillus subtilis used as biostimulators had beneficial effects on plant growth in several experiments, also in stress situations, as inappropriate EC and pH value. The biostimulators were used in single applications or as a mix in the rhizosphere, but the lactate was used at the beginning as foliar-fertilizer [14]. Therefore, it came to the thought to use the biostimulators to the root zone and on the leaves. The aim was to investigated which treatment is the most effective one. Experimental design is shown in **Table 9**, eight different treatments were

K-Humate (Fa. Humintech), Lactate (Fa. ECOFOL, **Table 2**) and *B. subtilis* FZB24® (Fa. ABITEP GmbH) was applied on leaves or on the substrate used in this experiment. Quantity and concentration of applied substances were deduces from

Cucumber plants were planted and cultivated in containers (volume of 7–8

Additional the plants were treated with one of the treatments, 20 ml per container and plant, three times in weekly intervals in following development stages: the first treatment in 5–6 leafs stage; second in 7–8 leafs stage; third in 9–10 leafs stage. For the variant -Leaf application- the different treatments were sprayed on the surface of leafs. In case of variant -Root application- the different treatments were given to the substrate and thereby into the rhizosphere of the plants, in the

The application of biostimulators three times in the growing stage (week 4, 5, and 6) affected development and yield of cucumber plants. The application of the biostimulators stimulated the growth represented by a higher fresh matter of shoots and leaves in most variants (**Figure 4**). Obviously, the location of application was important for the effect of the biostimulators. The application to the root zone

**application**

X X

**Root application**

liters) filled with Perlite. Nutrient solution was calculated following the HYDROFER program [13] to adjust the amounts of fertilizers, salts and acids required according the values (170 ppm N, 50 ppm P, 260 ppm K, 150 ppm Ca, 60 ppm Mg, 3 ppm Fe, 90 ppm HCO3). By trickle irrigation 2 to 4 times a day

250 ml per irrigation cycle was applied in period of 12–15 min.

**Treatment Concentration of substances Leaf**

*Concentrations and application patterns of biostimulators used in the experiment [17].*

Lactate 0,08% X X K-Humate 0,2% X X *Bacillus subtilis* (FZB24) Spore suspension (10/cfu/ml) X X

> Above mentioned concentration

Control —

nents are used together.

**cucumber plants**

compared with the control.

previous experience [14].

same amount and frequency.

Lactate +K-Humate + *Bacillus*

*subtilis*

**Table 9.**

**78**

*5.3.1 Shoot development*

*Fresh matter of leaves and shoots of cucumber plants after biostimulator application (lactate, K-Humate, B.subtilis BS) on leaves and roots respectively [17]. Different letters indicate significant differences (LSD, P = 0.05).*

induced in each case to a higher fresh matter compared to the control. If the Biostimulators were applied on the leaves, the effect on shoot fresh matter was not as strong in comparison to the application in the root zone. When *B. subtilis* (FZB24®) was used, the fresh mass of the shoot was even lower. It can be stated, if the combined biostimulator with all substances was applied the effect was different if applied over the roots was a stimulating effect visible, whereas if applied over the leaves an inhibiting effect for cucumber plant growth.

Comparing the effect of the treatments, also the quality of shoots and leaves seems to be different and effects on the weakness against fungi's could be expected. This effect was also found in experiments with Water spinach [18] however, in these experiments the effect on the root growth was much stronger than on the shoot growth.

Comparing the ratio between shoot and leaf fresh matter (**Figure 5**) there are no significant differences between all variants, but it seems the leaf application stronger stimulateed the leaf growth than shoot growth resulting in a lower ratio.

#### **Figure 5.**

*Effect of application biostimulators (lactate, K-Humate, FZB24®) on leaves and roots respectively on the ratio of shoots and leaf biomass after finishing the experiment [17]. No significant differences.*

However, the leaf treatment with the combination of all substances led to a reduction in leaf growth. After application of biostimulators via roots more or less the same ratio was found as in the control indicating the shoot and leaf growth was stimulated in the same manner.
