Organic fertilizer effect on Lettuce (Lactuca sativa L.) cultivated in nutrient film technology

Abstract

The survey was carried out in the Research Centre for the study of food products quality "HORTINVEST" between 2014-2015 using the Nutrient Film Technology (NFT) for the cultivation of lettuce. Three lettuce cultivars were used: Markies, Lollo bionda and Lollo rosa, together with three types of fertilizers: two organic fertilizers and a chemical one. Biometrical measurements on lettuce growth were conducted; also at the end of the cultivation cycle biochemical measurements were performed in order to assess plant quality. Also correlations between various biometrical parameters and influencing vegetal factors were settled. The results led towards gains in the plant growth rate, in the development of the leaf number and eventually in the production growth. For all lettuce varieties under research the total plant mass was higher due to organic fertilizers in comparison with plants under chemical fertilizer treatment. The plants organically fertilized proved to be superior as to the biochemical quality. Research was carried out in order to assess the quantitative and qualitative feedback of lettuce cultivated in Nutrient Film Technology (NFT) to various organic fertilizers which might replace chemical fertilizers.

Full text

Romanian BiotechnologicalLettersVol.21,No.5,2016
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ORIGINALPAP E R 

Romanian Biotechnological Letters, Vol. 21, No. 5, 2016

11905
Organic fertilizer effect on Lettuce (Lactuca sativa L.)
cultivated in nutrient film technology
Received for publication, September 09th, 2015
Accepted, October 10th, 2015
ELENA MARIA DRĂGHICI1, ELENA DOBRIN1, IONUȚ OVIDIU JERCA1,
IOANA MARIELA BĂRBULESCU1 STEFANA JURCOANE1, VIORICA
LAGUNOVSCHI-LUCHIAN 1
1University of Agronomic Sciences and Veterinary Medicine, 59 Mărăşti Blvd.,
district 1, Bucharest, Romania
*Corresponding author, e-mail: draghiciem@yahoo.com, vluchian@hotmail.com
Abstract
The survey was carried out in the Research Centre for the study of food products quality
“HORTINVEST” between 2014-2015 using the Nutrient Film Technology (NFT) for the cultivation of
lettuce. Three lettuce cultivars were used: Markies, Lollo bionda and Lollo rosa, together with three
types of fertilizers: two organic fertilizers and a chemical one. Biometrical measurements on lettuce
growth were conducted; also at the end of the cultivation cycle biochemical measurements were
performed in order to assess plant quality. Also correlations between various biometrical parameters
and influencing vegetal factors were settled. The results led towards gains in the plant growth rate, in
the development of the leaf number and eventually in the production growth. For all lettuce varieties
under research the total plant mass was higher due to organic fertilizers in comparison with plants
under chemical fertilizer treatment. The plants organically fertilized proved to be superior as to the
biochemical quality. Research was carried out in order to assess the quantitative and qualitative
feedback of lettuce cultivated in Nutrient Film Technology (NFT) to various organic fertilizers which
might replace chemical fertilizers.
Keywords: Lactuca sativa L., NFT system, organic fertilizers, quality.
1. Introduction
Lettuce (Lactuca sativa L.) is a highly appreciated vegetable, firstly due to its nutritional
qualities; this plant may be cultivated all year long, in all seasons, in various culture systems
(greenhouse, hothouse, open field). Recently, it has been largely cultivated in greenhouses
either in various substrata or using the Nutrient Film Technology (NFT). The plant grows on a
nutrient solution or on a nonreactive substratum. In either situation a fertilizer solution is
applied. NFT is an efficient system as to the water intake and fertilizers (KRATKY, 2005
[8]); lettuce with an average mass of 150-250 g has been obtained with an uptake of 3-6 l
nutrient solution per plant in this system. Cultivating lettuce without soil may lead to greater
quantity and quality (SILBER et al., 2003 [10]; SIKAWA AND YAKUPITIYAGE, 2010
[10]) and also in a 6 to 8 weeks’ period (AL-GHAWAS, and, AL-MAZIDI, 2004 [2]);
(KRATKY 2009 [7]); (IBRAHIM, ZUKI, 2014 [4]). Researches have shown that organic
fertilizers have improved both the quantity and the quality of lettuce. Lettuce quality can
be influenced both by the fertilizer type (ABD-ELMONIEM and all., 1996 [1]); (KARIMAEI
and all., 2004 [6]); (VILLAGA and all., 2012 [12]); (QIU et all., 2014 [9]) and by the light
quality (ITO ,1989 [5]); (DANISH, 1994 [3]). The aim of this survey is to replace the
chemical fertilizers with organic ones in the lettuce NFT cultivation.

ELENAMARIADRĂGHICI,ELENADOBRIN,IONUȚOVIDIUJERCA,IOANAMARIELABĂRBULESCU
STEFANAJURCOANE,VIORICALAGUNOVSCHI‐LUCHIAN
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Romanian Biotechnological Letters, Vol. 21, No. 5, 2016
11906
2. Materials and methods
The experiments were carried out in the greenhouse of the Research Centre for the study
of food products quality “HORTINVEST” between 2014-2015. The culture was grown using
the Nutrient Film Technology (NFT) system. Four types of fertilizers were used: three organic
fertilizers and a chemical one. The experimental fertilization variants were: V1 – Organic
Grow; V2 – Bio Leafez; V3 – Formulex; V4 – chemical fertilization. The total cultivated area
was of 160 m; 17.5 plants per one square meter in NFT. Three lettuce cultivars were used:
Markies, Lollo Bionda and Lollo Rosa having the following features: Markies – a lettuce
variety fit for indoor areas cultivated during autumn, winter or spring; head weight 400-600 g;
vegetation period: 50-60 days since planting; Lollo Bionda – a leaf lettuce (Lactuca Sativa
var. crispa) with shining light green colour and long and upright shape; it has crinkled and
frilly leaves; average mass: 300 g; Lollo Rosa – an early lettuce cultivar, with crinkled and
red leaves; vegetation period: 68 days; average mass: 250-300 g. The organic fertilizer
Organic Grow used all along the research had the following features: NPK ratio: 8: 3: 3;
microelements: nitrogen (total amount): 82.2 g/l, phosphorus: (P2O5) 30.3 g/l, potassium
(K2O) 32.1 g/l , boron 7 mg/l, calcium 390 mg/l, copper 2 mg/l, iron 120 mg/l, magnesium
850 mg/l, manganese 15 mg/l, zinc 12 mg/l, sodium 16.6 g/l, sulfides 0.4 g/l, pH 6.00. Bio
Leafez, organic fertilizer with a NPK ratio of 8: 3: 3 and microelements. Formulex with a
NPK ratio of 2.4: 0.9:3.4. For chemical fertilization Universol Green product was used having
a NPK ratio of 4-1-2. The content of the chemical fertilizer is as follows: nitrogen (total
amount 23 g/l; phosphorus (P2O5); potassium (K2O) 10 g/l¸ boron 0.01 g/l, copper 0.01 g/l,
iron 0.06 g/l, magnesium 2.5 g/l, manganese 0.04 g/l, zinc 0.01 g/l, pH 6.00. During the first
week after planting the electroconductibility was maintained at 0.7 mS/cm² and then as the
lettuce grew it was gradually reduced to 2.2 mS/cm². The solution pH level was constantly
maintained at 6.00. Observations and measurements were conducted on the dynamics of leaf
formation, lettuce leaf growth rate, plants’ diameter and mass. The determination of nitrites
and nitrates percentage was made in the agrochemistry laboratory of the Faculty of
Biotechnologies. Results have been statistical interpreted by variance analysis (ANOVA) for
p<0.05, according to Student test.
3. Results and discussions
During the cultivation period for each fertilizer an EC of 1.5 Microsiemens for the first
week and an EC of 1.8 Microsiemens for the rest of the vegetation period were provided.
A constant pH of 6.5 was observed during the entire period of time (Table 1). The light
regime was relatively constant for all cultivars under survey. The light intensity was measured
on a daily basis and the average of the recorded data, i.e. 7.92 Klux, exceeded the minimum
intensity level for lettuce (Soare Rodica, 2008).
Table 1. Data regarding EC, pH and the average light intensity during 2014-2015
Fertilizer EC
1st Stage
(Microsiemens)
EC
2nd Stage
(Microsiemens)
pH
Light intensity
(micromols)
Light
intensity
(Klux)
V1 Organic Grow 1,5 1,8 6,5 206,52 7,92
V2 Bio Leafez 1,5 1,8 6,5 206,52 7,92
V3 Formulex 1,5 1,8 6,5 206,52 7,92
V4 Chemical 1,5 1,8 6,5 206,52 7,92

OrganicfertilizereffectonLettuce(LactucasativaL.)cultivatedinnutrientfilmtechnology
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Romanian Biotechnological Letters, Vol. 21, No. 5, 2016
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The results of the lettuce plant growing of the analysed cultivars are presented in figures
1-3 while the statistic interpretation of the results are recorded in tables 2-4. For the Markies
cultivar (figure 1, table 2), the data obtained regarding the number of leaves grown on the
plant after 30 days from planting in NFT system showed that the chemical fertilized variety
developed the lowest number of leaves (17,66). It was further noticed that at all cultivars for
which organic fertilizers had been used, the plants formed a greater number of leaves ranging
from 21.33 (Formulex) to 24.11 (Bio Leafez) leaves, figure1.
Figure 1. Dynamics of leaf formed on plant at Markies cultivar
Table 2. Synthesis of the results regarding leaf formation – Markies cultivar
Difference Variant Leaves number
No. Number (%)
Significance
V 0 Average 21.61 3.95 122.35 ***
V1 23.33 5.67 132.11 ***
V2 24.11 6.45 136.52 ***
V3 21.33 3.67 120.78 ***
V4 17.66 0.00 100.00 Control
DL5% = 0.560 DL5% in % = 3.1710; DL1% = 0.810 DL1% in % = 4.5866; DL01% = 1.190 DL01% in %= 6.7384
In relation to Lollo bionda cultivar (figure 2, table 3), the lowest number of leaves was
registered at the chemical fertilized variety (9.66 leaves). All the organic fertilized varieties
formed a greater number of leaves in comparison with the chemical fertilized one. The
obtained values range from 10.33 leaves at the variant fertiliezed with Organic Grow to 11.66
leaves at the one fertilized with Bio Leafez.
The same trend was recorded at the Lollo Rosa cultivar, organic fertilized variants having
a greater number of leaves than the chemical fertilized one. The values have been as follows:
10.33 leaves at the chemical fertilized variant and 12.33 leaves at the variant for which
Organic Grow fertilizer was applied (figure 3).
Highly significant differences may be noticed at the Organic Grow fertilized variant of
the Lollo Rosa cultivar (table 4).
For the Markies and Lollo Rosa cultivars a very significant relation has been noted
between the fertilization variants and the number of leaves formed on the plant. The relation
is R² = 0.7868 for the Markies cultivar and R² = 0.942 for Lollo rosa variety (figures 4 a and
b.). The number of leaves formed on Lollo Rosa cultivar has not been significantly influenced
by the applied fertilizer (figure 5).

ELENAMARIADRĂGHICI,ELENADOBRIN,IONUȚOVIDIUJERCA,IOANAMARIELABĂRBULESCU
STEFANAJURCOANE,VIORICALAGUNOVSCHI‐LUCHIAN

Romanian Biotechnological Letters, Vol. 21, No. 5, 2016
11908
Figure 2. Dynamics of leaf formed on plant at Lollo Bionda cultivar
Table 3. Synthesis of the results regarding leaf formation – Lollo bionda cultivar
Difference Variant Leaves number
No. number (%)
Significance
V 0 Average 10.66 1.00 110.38 *
V1 10.33 0.67 106.94 N
V2 11.66 2.00 120.70 ***
V3 11.00 1.34 113.87 **
V4 9.66 0.00 100.00 Control
DL5% = 0.820 DL5% in % = 8.4886; DL1% = 1.180 DL1% in % = 12.2153; DL01% = 1.730 DL01% in % = 17.9089
Figure 3. Dynamics of formed leaf on plant at Lollo Rosa cultivar
Table 4. Synthesis of the results regarding leaf formation - Lollo Rosa cultivar
Difference Variant Leaves number
No. Number (%)
Significance
V 0 Average 11.23 0.90 108.69 *
V1 12.33 2.00 119.36 ***
V2 11.25 0.92 108.91 **
V3 11.00 0.67 106.49 *
V4 10.33 0.00 100.00 Mt
DL5% = 0.640 DL5% in % = 6.1955; DL1% = 0.920 DL1% in % = 8.9061; DL01% = 1.350 DL01% in % = 13.0687

OrganicfertilizereffectonLettuce(LactucasativaL.)cultivatedinnutrientfilmtechnology
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Romanian Biotechnological Letters, Vol. 21, No. 5, 2016
11909
a b
Figure 4. Influence of fertilizers on number of leaves at Markies
(a) and Lollo rosa (b) cultivars
Figure 5. Influence of fertilizers on number of
leaves at Lollo Bionda cultivar
As for the plant total mass (figure 6, table 5-7) it has been noted that the Markies cultivar
registered the highest average mass for the variant at which the organic fertilizer Organic
Grow was applied (422.25 g/plant), and the lowest average mass of 397.11g was recorded at
the chemical fertilized variant. For Lollo bionda and Lollo rosa cultivars, the lowest average
mass has also been found for the chemical fertilized variant: Lollo bionda – 201.33 g and
Lollo Rosa cultivar – 187.25 g. When the BioLeafez fertilizer was applied, plants with an
average mass of 413.15 g were obtained at the Markies cultivar, while for Lollo bionda and
Lollo rosa varieties plants registered an average mass of 255.33 g and respectively 258.25 g.
Figure 6. Average mass of lettuce plants
The statistical analysis (Duncan test) for Markies cultivar highlighted the V1 variant that
was fertilized with Organic Grow and a distinct statistical difference was observed (Table 5).
Table 5. Synthesis of the results on average lettuce mass – MARKIES cultivar
Difference Variant Total mass
(g) (g) (%)
Significance
V 0 AVERAGE 410.96 13.85 103.49 N
V1 422.25 25.14 106.33 **
V2 413.15 16.04 104.04 *
V3 411.33 14.22 103.58 *
V4 397.11 0.00 100.00 Mt
DL5% = 14.020 DL5% in % = 3.5305; DL1% = 20.150 DL1% in % = 5.0742; DL01% = 29.600 DL01% in % = 7.4539

ELENAMARIADRĂGHICI,ELENADOBRIN,IONUȚOVIDIUJERCA,IOANAMARIELABĂRBULESCU
STEFANAJURCOANE,VIORICALAGUNOVSCHI‐LUCHIAN

Romanian Biotechnological Letters, Vol. 21, No. 5, 2016
11910
As for Lollo Bionda and Lollo Rosa cultivars highly significant statistical differences
have been recorded for the plant mass in comparison with control variant 4 (Tables 6 and 7).
Table 6. Synthesis of the results on average lettuce mass – Lollo Bionda cultivar
Difference Variant Total mass
(g) (g) (%)
Significance
V 0 - average 240.04 38.71 119.23 ***
V1 256.25 54.92 127.28 ***
V2 255.33 54.00 126.82 ***
V3 247.25 45.92 122.81 ***
V4 201.33 0.00 100.00 Mt
DL5% = 7.210 ; L5% in % = 3.5812; DL1% = 10.360; DL1% in % = 5.1458; DL01% = 15.220; DL01% in %= 7.5597
Table 7. Synthesis of the results on average lettuce mass – Lollo Rosa cultivar
Difference Variant Total mass
(g) (g) (%)
Significance
V 0 - average 237.99 50.74 127.10 ***
V1 255.33 68.08 136.36 ***
V2 258.25 71.00 137.92 ***
V3 251.11 63.86 134.10 ***
V4 187.25 0.00 100.00 Mt
DL5% = 9.150; DL5% in % = 4.8865; DL1% = 13.150; DL1% in % = 7.0227; DL01% = 19.310 DL01% in %= 10.3124
Analyzing the correlations between the fertilizers and the average mass of the plants, it
has been concluded that the fertilizer has a important influence. For the cultivars in question
the correlations have been as follows: R² = 0.9201 for Markies, R² = 0.7297 for Lollo Bionda
and R² = 0.6461 for Lollo Rosa (figures 7-9).
Figure 7. Influence of the fertilizer upon the average
mass of the lettuce heads – Markies
Figure 8. Influence of the fertilizer upon the average
mass of the lettuce rosette – Lollo bionda
Such results are corroborated with the results on the average daily growth rate and also
with the results on the average daily rate growth of mass accumulation at the level of the
lettuce rosette – see Table 8. Noticeable is the Markies head because of the average daily
rate growth – which is almost twice higher – and the daily rate growth of mass accumulation
which is at least 70% higher in comparison with the rate of leaf lettuce varieties (Lollo bionda

OrganicfertilizereffectonLettuce(LactucasativaL.)cultivatedinnutrientfilmtechnology
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Romanian Biotechnological Letters, Vol. 21, No. 5, 2016
11911
and Lollo rosa), irrespective of the applied fertilizer. Figure 10 shows the strong bondage
between the two synthetical indices (R2=0.9178) irrespective of the applied fertilizers.
Figure 9. Influence of the fertilizer upon the average mass of the lettuce rosette – Lollo rosa
Table 8. Average daily rate of growth and average daily rate of mass accumulation of lettuce rosettes
Cultivars Variants Average daily growth rate
(no. leaf / day)
Average daily rate of mass accumulation
(g/day)
V0 average 0.72 13.69
V1 0.78 14.07
V2 0.80 13.77
V3 0.71 13.71
Markies
V4 0.59 13.23
V0 average 0.35 8.00
V1 0.34 8.54
V2 0.39 8.51
V3 0.37 8.24
Lollo bionda
V4 0.32 6.71
V0 average 0.37 7.93
V1 0.41 8.51
V2 0.37 8.61
V3 0.37 8.37
Lollo rosa
V4 0.34 6.24
Figure 10. Relationship between average daily rate of growth
and average daily rate of mass accumulation

ELENAMARIADRĂGHICI,ELENADOBRIN,IONUȚOVIDIUJERCA,IOANAMARIELABĂRBULESCU
STEFANAJURCOANE,VIORICALAGUNOVSCHI‐LUCHIAN

Romanian Biotechnological Letters, Vol. 21, No. 5, 2016
11912
The marketing quality of the lettuce is appreciated mainly considering the plant mass
according to the quality standards and considering the percentage of nitrates and nitrites. It
has been assessed that the plant mass of all NFT cultivated variants is within the limits of the
quality standards. Data on nitrates and nitrites percentage calculated for the NFT-cultivated
lettuce are displayed in Table 9. Tests have shown lower values for variants with organic
fertilizers. Also it is noticeable that the culture period may have influenced the percentage of
nitrates and nitrites – possibly due to the decrease of the daylight period.
Table 9. Nitrates and nitrites percentage calculated for the NFT-cultivated lettuce
Type of fertilization Cultivar mg NO2 - / kg mg NO3 - / kg
Markies 0,69 138,1
Lollo bionda 0,39 99,3
Organic fertilization
Lollo rosa 0,41 93,6
Markies 0,83 177,6
Lollo bionda 0,66 163,2
Chemical fertilization
Lollo rosa 0,68 161,6
4. Conclusions
In an overall regard over the obtained results, we can notice that the NFT-cultivated
lettuce variants have differentiated feedbacks as to various fertilizers. The result analysis and
statistical apprehension have shown that, irrespective of the cultivated lettuce variants and
irrespective of the genetic specificity, the organic fertilization is significantly superior to the
control variant, with mineral fertilization, for all studied indices. The Markies cultivar (which
is a lettuce variety cultivated for its head) had a special growth and development in
comparison with leaf lettuce such as Lollo bionda and Lollo rosa. This growth and
development specificity has shown a clearer influence of fertilizers used for Markies in
comparison with Lollo bionda and Lollo rosa. Consequently, irrespective of the analysed
index, variants organically fertilized are significantly superior to the control variant.
5. Acknowledgements
This work was supported by a grant of the Romanian National Authority for Scientific
Research, CNDI – UEFISCDI, financed from project number PN-II-PT-PCCA-2011-3.2-
1351 - Contract No. 68/2012.
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