**5. Effects of biostimulators on the growth and cucumber plant development**

### **5.1 Mineral and organic substrates used in substrate culture of cucumbers treated with biostimulators**

In Europe, about 87 million sheep are produced, in Germany about 2.2 million. Often, there is a lack of capacity for cleaning the sheep wool, so unclean sheep wool is available as waste material.

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

The objective of this experiment was to investigate the development and yield of cucumber grown on sheep wool slabs in comparison with peat and coconut fiber slabs as well as Rockwool slabs and perlite in containers. Different sheep wool slabs in size and added components were tested, the highest stability was obtained with sheep wool slabs in combination with coconut fibers.

In this experiment following questions were investigated:


Sheep wool slabs used in this experiment were compared with the following substrates [12]:


In this experiment fifty percent of the cucumber plants of each substrate variant were treated three times with a biostimulator solution containing 0.08% K-Humate (Fa. Humintech), 0.2% Lactofol (O) (Fa. ECOFOL) and a spore suspension (10<sup>7</sup> cfu ml<sup>1</sup> ) of *Bacillus subtilis* FZB 24®. To the plants were applied 20 ml of this solution three times in weekly intervals starting with first treatment in 6–7 leaves stage, after transplanting. Plants of *Cucumis sativus* L. 'Indira' were used for the experiment. The experiment was conducted during two cultivation periods, first from November until April and second from June until November in the next year.

#### *5.1.1 Effects of biostimulators growing cucumbers in mineral and organic substrates*

For the soilless cultivation of the cucumber plants substrates was selected with different physical properties (**Table 5**). In general substrates for cucumbers should have high air capacity with a range between 20 to 40%, during the cultivation time often the air capacity is decreasing very much and water capacity increasing, therefore a certain stability is necessary in this regard. Sheep wool had the highest air capacity with about 70%, while peat had the lowest air capacities with 18%. The peat slabs were pressed to reduce the volume for the transport, the expansion of the slabs needs time. Because the low water capacity of sheep wool at the beginning, a water reserve is missing in case of low water availability. It seems that sheep wool and perlite requires a higher and more stable supply with nutrient solution than the other substrates. The physical properties after second use of the substrates

yield of the investigated substrates in the examined months (**Table 4**) can be due,

**Substrate Months of harvest Average February March April May June July** Rockwool 0.40 b 4.95 b 6.90 a 7.78 a 6.80 bc 5.77 b 5.43 Perlite 1.45 a 4.78 b 6.63 ab 6.54 ab 7.10 b 8.48 a 5.83 UM-Foam 1.10 a 4.30 b 6.10 ab 5.65 b 6.60 c 8.05 a 5.30 Organic Subst. 1.37 a 6.24 a 7.36 a 7.14 a 9.25 a 7.27 a 6.44

*Physical and chemical characteristics of substrates used in experiments with cucumber growing in substrate*

• lower substrate temperatures and lower water holding capacities in urea foam

• higher temperatures and better sorption capacity in the organic substrate

The development of the leaf area of cucumber plants was examined for the variants with rockwool mats, urea foam and perlite. The following leaf areas were

, in urea foam

*).*

**Chemical characteristics**

**] pH CEC (mval/1)**

determined as the mean of all measuring dates: in rockwool 8215 cm2

.

**5. Effects of biostimulators on the growth and cucumber plant**

**5.1 Mineral and organic substrates used in substrate culture of cucumbers**

In Europe, about 87 million sheep are produced, in Germany about 2.2 million. Often, there is a lack of capacity for cleaning the sheep wool, so unclean sheep wool

because different growing conditions, as:

*Different letters indicate significant differences, LSD, p* ≤ *0.05.*

**Substrates Physical characteristics**

*Cucumber Economic Values and Its Cultivation and Breeding*

**[% v/v]**

*WC = water capacity; AC = air capacity; PV = pore volume; CEC = cation exchange capacity.*

**WC AC PV Density [kg/m3**

Rockwool 54 32 86 80 7.5–8.8 — Perlite 36 52 88 98 6.5–8.0 5 UM-Foam 45 45 90 25 6.0–6.7 2 Organic Substrate (OM) 50 40 90 350 6.0–6.5 165 Target values \* 45–65 20–40 70–95 30–500 6.7–7.0 50

*Yield of greenhouse cucumber in mineral, artificial and organic substrate (kg/m<sup>2</sup>*

, and in perlite 7438 cm2

**treated with biostimulators**

is available as waste material.

and perlite

**development**

7889 cm2

**72**

**Table 4.**

*\* [1].*

**Table 3.**

*culture.*


*AC – air capacity, WC – water capacity, PV - volume.*

*Different letters indicate significant differences (Tukey P < 0.05) within one parameter.*

#### **Table 5.**

*Physical properties of mineral and organic substrates for cucumber cultivation [12].*

were changed, in Coconut fiber and rockwool slabs the AC was below the target value.

The analyses of the mineral content of the substrates used for cucumber cultivation (**Table 6**) showed different results after the first and after second use. There was no accumulation of nutrients in the sheep wool, peat and coconut fiber slabs, but very high accumulation of NO3 in perlite and and K in rockwool. Furthermore, In the coconut fiber slabs could be determined a high accumulation of NO3 and Ca. In general, it can be stated that the nutrient values in the substrates do not show any unusual fluctuations. it must also be taken into account that the sorption capacity and the mineralization in the substrates are different, but the same nutrient solution was always added.

higher if the variants were treated with the biostimulators. The highest yield could be obtained for cucumber cultivated in the second cultivation in sheep wool slabs and peat slabs and treated with biostimulators. The lowest cucumber yield in the second year was obtained in the substrate variants rockwool slabs and perlite.

*Cucumber yield in organic substrates (sheep wool slabs, peat slabs, coconut fiber slabs) and mineral substrates*

*(perlite, Rockwool slabs) not treated with biostimulators and treated with them [12].*

Sheep wool slabs 1.08 abcd 1.94 d 8.96 e 10.07 f Peat slabs 0.57 a 1.28 abcd 7.49 c 10.41 f Coconut fiber slabs 0.76 ab 0.84 abc 7.51 c 8.09 d Perlite 0.77 ab 1.16 abcd 6.68 b 8.95 e Rockwool slabs 1.47 bcd 1.71 cd 6.11 a 9.16 e

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

*Treated – application of biostimulators (0.08% K-Humate, 0.2% Lactofol (O), spore suspension (10<sup>7</sup> cfu/ml) of* Bacillus subtilis *FZB 24® Different letters indicate significant differences (Tuckey 0.05; comparison within one*

**)**

**First cultivation Second cultivation Untreated Treated Untreated Treated**

**Substrates Yield (kg plant<sup>1</sup>**

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

biostimulators were undertaken regarding the effects:

the strain FZB24®,

*Untreated – no application of biostimulators.*

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

*cultivation).*

**Table 7.**

lactates and FZB24®),

period of 12–15 min.

**75**

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

• of different humate and lactate types, whereas from *Bacillus subtilis* was used

• of concentrations and frequencies of biostimulators applications (humates,

in the nutrient solution, or direct to the leaves adaxial or abaxial)

values), suboptimal pH and suboptimal temperature

• on the nutrient uptake of N, P, K, Ca, Mg and Fe

• of the best method of applications (in the rhizosphere, to the growing media or

• in stress situations during growth of the cucumber plants, e.g. salt stress (EC

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

In all variants, the yield was higher in the second cultivation (**Table 7**) for all substrates tested. Furthermore, in all substrate variants the cucumber yield was


#### **Table 6.**

*Nutrient content in the tested substrates after the first and second cultivation of cucumbers.*

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


*Untreated – no application of biostimulators.*

*Treated – application of biostimulators (0.08% K-Humate, 0.2% Lactofol (O), spore suspension (10<sup>7</sup> cfu/ml) of* Bacillus subtilis *FZB 24® Different letters indicate significant differences (Tuckey 0.05; comparison within one cultivation).*

#### **Table 7.**

were changed, in Coconut fiber and rockwool slabs the AC was below the target

*Different letters indicate significant differences (Tukey P < 0.05) within one parameter.*

*Physical properties of mineral and organic substrates for cucumber cultivation [12].*

The analyses of the mineral content of the substrates used for cucumber cultivation (**Table 6**) showed different results after the first and after second use. There was no accumulation of nutrients in the sheep wool, peat and coconut fiber slabs, but very high accumulation of NO3 in perlite and and K in rockwool. Furthermore, In the coconut fiber slabs could be determined a high accumulation of NO3 and Ca. In general, it can be stated that the nutrient values in the substrates do not show any unusual fluctuations. it must also be taken into account that the sorption capacity and the mineralization in the substrates are different, but the same nutrient solution

**Substrate Before use in the experiment After second use in the experiment**

Sheep wool slabs 69.4 f 22.8 a 96.8 e 43.1 cd 44.1 cd 87.2 abc Peat slabs 18.0 a 68.0 g 86.0 b 30.7 b 61.6 f 92.3 d Coconut fiber slabs 30.6 b 52.8 e 83.9 a 20.0 a 72.3 g 92.3 d Perlite 58.6 e 31.6 b 90.2 bcd 41.4 c 50.4 e 91.8 d Rockwool slabs 49.2 d 41.6 c 90.7 cd 17.2 a 74.6 g 90.1 bcd

**AC (%) WC (%) PV (%) AC (%) WC (%) PV (%)**

In all variants, the yield was higher in the second cultivation (**Table 7**) for all substrates tested. Furthermore, in all substrate variants the cucumber yield was

**Substrate Nutrients First cultivation (ppm) Second cultivation (ppm)**

Sheep wool slabs NO3 21.6 a 23.6 a Peat slabs 77.9 c 77.1 bc Coconut fiber slabs 68.2 c 85.2 c Perlite 34.7 b 65.6 b Rockwool slabs 345.1 d 248.1 d Sheep wool slabs K 28.4 a 24.2 a Peat slabs 115.7 d 72.4 c Coconut fiber slabs 113.2 d 75.8 c Perlite 55.3 b 56.6 b Rockwool slabs 70.4 c 235.9 d Sheep wool slabs Ca 33.8 b 32.7 a Peat slabs 64.9 d 73.7 b Coconut fiber slabs 55.7 c 82.9 bc Perlite 24.6 a 92.3 cd Rockwool slabs 115.3 e 96.6 d

*Different letters indicate significant differences (Tukey P < 0.05) within the cultivation.*

*Nutrient content in the tested substrates after the first and second cultivation of cucumbers.*

value.

**Table 6.**

**74**

**Table 5.**

was always added.

*AC – air capacity, WC – water capacity, PV - volume.*

*Cucumber Economic Values and Its Cultivation and Breeding*

*Cucumber yield in organic substrates (sheep wool slabs, peat slabs, coconut fiber slabs) and mineral substrates (perlite, Rockwool slabs) not treated with biostimulators and treated with them [12].*

higher if the variants were treated with the biostimulators. The highest yield could be obtained for cucumber cultivated in the second cultivation in sheep wool slabs and peat slabs and treated with biostimulators. The lowest cucumber yield in the second year was obtained in the substrate variants rockwool slabs and perlite.
