Effect of potassium humate and nitrogen fertilizer on herb - Ozean ...

Journal <strong>of</strong> Applied Sciences 2(3), 2009
Ozean Journal <strong>of</strong> Applied Sciences 2(3), 2009
ISSN 1943-2429
© 2009 Ozean Publication
EFFECT OF POTASSIUM HUMATE AND NITROGEN FERTILIZER ON HERB AND
ESSENTIAL OIL
OF OREGANO UNDER DIFFERENT IRRIGATION INTERVALS
*Said-Al Ahl H. A. H.;** Hasnaa S. Ayad <strong>and</strong> *S. F. Hendawy
* Department <strong>of</strong> Cultivation <strong>and</strong> Production <strong>of</strong> Medicinal <strong>and</strong> Aromatic Plants
** Department <strong>of</strong> Botany
National Research Centre, Dokki, Giza, Egypt.
*E-mail address for correspondence: saidalahl@yahoo.com
___________________________________________________________________________________________
Abstract: Two pot trials were carried out during the 2006 <strong>and</strong> 2007 seasons to investigate the impact <strong>of</strong>
irrigation intervals (3, 5 <strong>and</strong> 7 days), <strong>potassium</strong>-<strong>humate</strong> (spraying at 1%) <strong>and</strong>/or <strong>nitrogen</strong> <strong>fertilizer</strong> levels
(0, 0.6 <strong>and</strong> 1.2 g N pot -1 as ammonium sulphate) on the fresh weight <strong>of</strong> herb <strong>and</strong> essential oil <strong>of</strong> oregano
plants. Irrigating plants every 7 days <strong>and</strong> with 1.2 g N pot -1 was effective in raising the productivity <strong>of</strong> herb
<strong>and</strong> the content <strong>and</strong> yield <strong>of</strong> essential oil. The interaction between these treatment gave the best results.
Concerning essential oil constituents, carvacrol was the major compound followed by P-cymene; γ–
terpinene was the third component
Key words: Origanum vulgare L., irrigation intervals, <strong>nitrogen</strong> <strong>fertilizer</strong>, <strong>potassium</strong> <strong>humate</strong>, fresh herb
yield, essential oil, GLC analysis
___________________________________________________________________________________________
INTRODUCTION
Oregano (Origanum vulgare L.) belongs to the Lamiaceae family, which is indigenous to the
Mediterranean region. It also is distributed <strong>and</strong> cultivated in many areas <strong>of</strong> the mild, temperate climates <strong>of</strong>
Europe, Asia, North Africa, <strong>and</strong> America (Ietswaart, 1980; Goliaris et al., 2002). Oregano plays a primary
role among culinary herbs in world trade. Traditionally, leaves <strong>and</strong> flowers <strong>of</strong> oregano are used in Lithuania
mostly for their beneficial properties to cure cough <strong>and</strong> sore throats <strong>and</strong> relieve digestive complaints (Ien et
al., 2008). Oregano contains essential oils, rich in the two isomeric phenols carvacrol <strong>and</strong> thymol (Fleisher
<strong>and</strong> Sneer, 1982; Kokkini <strong>and</strong> Vokou, 1989 <strong>and</strong> Vokou et al., 1993). The use <strong>of</strong> oregano as a medicinal
plant is attributed to the biological properties <strong>of</strong> the herb <strong>and</strong> its essential oil composition. Findings report
that oregano is antimicrobial (Didry et al., 1993; Chun et al., 2005 <strong>and</strong> Paster et al., 2005), an antioxidant
(Capecka et al., 2005 <strong>and</strong> Jaloszynski et al., 2008), <strong>and</strong> probably stimulates the appetite (Ien et al., 2008).
The content <strong>of</strong> essential oils <strong>and</strong> their composition are affected by different factors, including genetic
makeup (Muzik et al., 1989) <strong>and</strong> cultivation conditions, such climate, habitat, harvesting time, water stress,
<strong>and</strong> the use <strong>of</strong> <strong>fertilizer</strong> (Min et al., 2005; <strong>and</strong> Stute, 2006).
Plant reactions are affected by the amount <strong>of</strong> soil water directly or indirectly. Drought stress limits the
production <strong>of</strong> 25% <strong>of</strong> the world's l<strong>and</strong> (Delfine et al., 2005). Water stress in plants influences many
metabolic processes, <strong>and</strong> the extent <strong>of</strong> its effects depends on drought severity. The optimization <strong>of</strong>
irrigation for the production <strong>of</strong> fresh herbs <strong>and</strong> essential oils is important, since water is a major component
<strong>of</strong> the fresh produce <strong>and</strong> affects both weight <strong>and</strong> quality (Jones <strong>and</strong> Tardien, 1998). Water deficit in plants
may lead to physiological disorders, such as a reduction in photosynthesis <strong>and</strong> transpiration (Sarker et al.,
2005), <strong>and</strong> in the case <strong>of</strong> aromatic plants may cause changes in the yield <strong>and</strong> composition <strong>of</strong> their essential
oils. For example, water deficit decreased the oil yield <strong>of</strong> rosemary (Rosmarinus <strong>of</strong>ficinalis L.) (Singh <strong>and</strong>
Ramesh, 2000) <strong>and</strong> anise (Pimpinella anisum L.) (Zehtab- Salmasi et al., 2001). By contrast, water stress
caused an increase in oil production <strong>of</strong> thyme (Aziz et al., 2008) <strong>and</strong> citronella grass (Cymbopogen
winterianus Jowitt.) expressed on the basis <strong>of</strong> plant fresh weight. The severity <strong>of</strong> the water stress response
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varied with cultvar <strong>and</strong> plant density (Fatima et al., 2000). The improvement <strong>of</strong> plant nutrition can
contribute to increased resistance <strong>and</strong> production when the crop is submitted to water stress.
Humic substances are organic compounds that result from the decomposition <strong>of</strong> plant <strong>and</strong> animal materials.
Humic acid <strong>and</strong> their salts which derived from coal <strong>and</strong> other sources may provide a viable alternative to
liming, to ameliorate soil acidity <strong>and</strong> improve soil structurel stability. Research has shown it is the humic
fractions (humic acid, fulvic acid <strong>and</strong> humin) <strong>of</strong> the soil organic matter that are responsible for the generic
improvement <strong>of</strong> soil fertility <strong>and</strong> improved productivity (Kononova 1966 <strong>and</strong> Fortun et al 1989), the same
author added that humic acids are known to posses many beneficial agricultural properties, they participate
actively in the decomposition <strong>of</strong> organic matter, rocks <strong>and</strong> mineral, improve soil structure <strong>and</strong> change
physical properties <strong>of</strong> soil, promote the chelation <strong>of</strong> many elements <strong>and</strong> make these available to plants, aid
in in correcting plant chlorisis, enhancement <strong>of</strong> photosynthesis density <strong>and</strong> plant root respiration has
resulted in greater plant growth with <strong>humate</strong> application (Smidova, 1960 <strong>and</strong> Chen <strong>and</strong> Avid, 1990).
Increase the permeability <strong>of</strong> plant membranes due to <strong>humate</strong> application resulted in improve growth <strong>of</strong>
various groups <strong>of</strong> beneficial microorganisms, accelerate cell division, increased root growth <strong>and</strong> all plant
organs for a number <strong>of</strong> horticultural crops <strong>and</strong> turfgrasses, as well as, the growth <strong>of</strong> some trees, Russo <strong>and</strong>
Berlyn (1990), S<strong>and</strong>ers et al (1990) <strong>and</strong> Poincelot (1993).
Plant nutrition is one <strong>of</strong> the most important factors that increase plant production. Nitrogen is most
recognized in plants for its presence in the structure <strong>of</strong> the protein molecule. In addition, <strong>nitrogen</strong> is found
in such important molecules as purines, pyrimidines, porphyrines, <strong>and</strong> coenzymes. Purines <strong>and</strong> pyrimidines
are found in the nucleic acids RNA <strong>and</strong> DNA, which are essential for protein synthesis. The porphyrin
structure is found in such metabolically important compounds as the chlorophyll pigments <strong>and</strong> the
cytochromes, which are essential in photosynthesis <strong>and</strong> respiration. Coenzymes are essential to the function
<strong>of</strong> many enzymes. Accordingly, <strong>nitrogen</strong> plays an important role in synthesis <strong>of</strong> the plant constituents
through the action <strong>of</strong> different enzymes. Nitrogen limiting conditions increase volatile oil production in
annual herbal. Nitrogen fertilization has been reported to reduce volatile oil content in Juniperus
horizontalis [creeping juniper] (Fretz, 1976), although it has been reported to increase total oil yield in
thyme [Thymus vulgaris] (Baranauskienne et al., 2003). However, studies on agronomic factors such as
application <strong>of</strong> <strong>potassium</strong> <strong>humate</strong> <strong>and</strong> irrigation intervals as well as <strong>nitrogen</strong> fertilization on yield <strong>and</strong>
essential oils <strong>of</strong> oregano have not been investigated thoroughly until now.
This study aimed to evaluate the effect <strong>of</strong> <strong>nitrogen</strong> fertilization, application <strong>of</strong> <strong>potassium</strong> <strong>humate</strong> <strong>and</strong>
irrigation intervals on the fresh herb yield <strong>and</strong> essential oil content <strong>and</strong> their main constituents <strong>of</strong> Origanum
vulgare L.
MATERIALS AND METHODS
The experiment was carried out under the natural conditions <strong>of</strong> the greenhouse <strong>of</strong> the National Research
Center, Dokki, Giza, Egypt, during the two seasons <strong>of</strong> 2006 <strong>and</strong> 2007. Seeds <strong>of</strong> oregano were obtained
from Jellitto St<strong>and</strong>ensamen Gmbh, Schwarmstedt, Germany <strong>and</strong> were seeded in the nursery on 15 th
November 2005 <strong>and</strong> 2006. The seedlings were transplanted into pots 30 cm diameter, on the 15 th February
<strong>of</strong> each season. Each pot contained three seedlings <strong>and</strong> was placed in full sun light. Each pot was filled with
10 kg <strong>of</strong> air dried soil. The soil related to the typic torrifluvents. The physical <strong>and</strong> chemical analyses <strong>of</strong> the
soil were determined according to Jackson 1973. The soil texture was s<strong>and</strong>y loam, having a physical
composition as follows: 44.50% s<strong>and</strong>, 28.80% silt, 26.70% clay, <strong>and</strong> 0.85% organic matter. The results <strong>of</strong>
soil chemical analysis were as follows: pH= 8.25; E.C (mmohs/cm) = 0.87; <strong>and</strong> total <strong>nitrogen</strong> =0.11 %;
available phosphorus =2.33 mg/100gram; <strong>potassium</strong>= 0.019 mg/100gram.
The experimental layout was factorial in a complete r<strong>and</strong>omized design (CRD), with three replications.
Each replication contained seven pots, while the pot contained three plants. Ammonium sulphate (20.50%)
was applied at the rate <strong>of</strong> 0.0 (N0), 0.6 (N1) <strong>and</strong> 1.2 (N2) g N pot -1 as a top dressing application <strong>and</strong>
divided into two equal portions. The first portion was added one month after transplanting, <strong>and</strong> the second
N addition, was added five months after transplanting. Then, after the first N addition, irrigation intervals
(3, 5 <strong>and</strong> 7 days), one litre <strong>of</strong> water was applied per one pot. The <strong>potassium</strong> <strong>humate</strong> used in this study is
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produced in China having a physical data as follows: appearance (black powders), pH (9-10), <strong>and</strong> water
solubility (> 98%). The guarateed analysis were as follows: humic acid (80%), <strong>potassium</strong> (K 2 O) (10-12%),
<strong>and</strong> zinc, iron, manganese, etc., (100 ppm). Plants were sprayed with twice freshly prepared solution <strong>of</strong>
<strong>potassium</strong> <strong>humate</strong> (1 %), in addition to the untreated plants (control) which were sprayed with tap water.
The plants treated with K-<strong>humate</strong> two times <strong>of</strong> 75 <strong>and</strong> 180 days from transplanting, respectively in both
seasons. Plant fresh weight (g plant -1 ) <strong>of</strong> each replicate was determined in the first <strong>and</strong> second cuts after
105 <strong>and</strong> 210 days from transplanting, respectively. The essential oil percentage was determined in the fresh
herb <strong>of</strong> each replicate. To extract <strong>and</strong> quantify the essential oils, a weight <strong>of</strong> 100 g <strong>of</strong> fresh herb, during two
cuts in both seasons was separately subjected to hydro-distillation for 3 hours using a modified Clevenger
apparatus according to Gunther (1961). Essential oil percentage <strong>of</strong> each replicate was determined <strong>and</strong>
expressed as (%), while essential oil yield per plant was expressed as ml plant -1 . The essential oils <strong>of</strong> each
treatment were collected <strong>and</strong> dehydrated over anhydrous sodium sulphate <strong>and</strong> kept in a refrigerator until
gas-liquid chromatography (GLC) analyses. The GLC analysis <strong>of</strong> the oil samples was carried out in the
second season using a Hewlett Packard gas chromatograph apparatus at the Central Laboratory <strong>of</strong> the
National Research Center (NRC) with the following specifications: instruments: Hewlett Packard 6890
series, column; HP (Carbwax 20M, 25m length x 0.32mm I.D), film thickness: 0.3mm, sample size: 1µl,
oven temperature: 60-190°C, Program temperature: 60°C/2min, 8°C/min, 190°C/25min, injection port
temperature:240°C, carrier gas: <strong>nitrogen</strong>, detector temperature (FID): 280°C, flow rate: N 2 3ml/min., H 2
3ml/min., air 300ml/min. Main compounds <strong>of</strong> the essential oil were identified by matching their retention
times with those <strong>of</strong> the authentic samples that were injected under the same conditions. The relative
percentage <strong>of</strong> each compound was calculated from the peak area corresponding to each compound. Except
for the constituents <strong>of</strong> the essential oils, the data in the present study were analyzed with the Analysis <strong>of</strong>
Variance (ANOVA) with three replications according to Snedcor <strong>and</strong> Cochran (1981). Duncan's multiple
range test were used to compare between the means <strong>of</strong> treatments according to Waller <strong>and</strong> Duncan (1969)
at probability 5 %.
Herb fresh weight:
RESULTS AND DISCUSSIONS
Data presented in Table (1) indicated that <strong>nitrogen</strong> fertilization, <strong>potassium</strong>-<strong>humate</strong> <strong>and</strong>/or irrigation
intervals affected plant fresh weight in both cuts <strong>of</strong> both seasons. Increasing the period <strong>of</strong> irrigation
increased plant fresh weight. The highest mean values due to irrigation treatments were recorded with
plants that received the highest amounts <strong>of</strong> water (irrigated every 3 days). The pronounced effect <strong>of</strong>
increased irrigation on fresh herb yield may be attributed to the availability <strong>of</strong> sufficient moisture around
the root concentrated <strong>and</strong> thus a greater proliferation <strong>of</strong> root biomass resulting in the higher absorption <strong>of</strong>
nutrients <strong>and</strong> water leading to production <strong>of</strong> higher vegetative biomass (Singh et al., 1997). It was found
that increasing levels <strong>of</strong> water stress reduce growth <strong>and</strong> yield due to reduction in photosynthesis <strong>and</strong> plant
biomass. Under increasing water- stress levels photosynthesis was limited by low Co2 availability due to
reduced stomatal <strong>and</strong> mesophyll conductance. Drought stress iassociated with stomatal closure <strong>and</strong> thereby
with decreased CO2 fixation. However, the effect <strong>of</strong> irrigation repeated in every 4 days seemed to be
optimal <strong>and</strong> produced the highest production <strong>of</strong> fresh biomass (Srivastava, <strong>and</strong> Srivastava, 2007). The
superiority <strong>of</strong> the plants that received the highest rate <strong>of</strong> irrigation treatments in producing the heaviest total
plant fresh weight was in agreement with that <strong>of</strong> Thabet et al. (1994); Mahmoud (2002); El-Naggar et al.
(2004); Moeini Alishah et al. (2006) <strong>and</strong> Aziz et al. (2008).
Increasing <strong>nitrogen</strong> doses increased plant fresh weight at all doses in the two cuts in both seasons. These
doses had increased plant fresh weight compared to the control treatment. The stimulation effects <strong>of</strong>
applying <strong>nitrogen</strong> on vegetative growth may be attributed to the well known functions <strong>of</strong> <strong>nitrogen</strong> in plant
life, as described in the Introduction. Moreover, <strong>nitrogen</strong> is involved in many organic compounds <strong>of</strong> the
plant system. A sufficient supply <strong>of</strong> various <strong>nitrogen</strong>ous compounds is, therefore, required in each plant cell
for its proper functioning. Generally, the enhancing effect <strong>of</strong> N-fertilization on plant growth may be due to
the positive effects <strong>of</strong> <strong>nitrogen</strong> on activation <strong>of</strong> photosynthesis <strong>and</strong> metabolic processes <strong>of</strong> organic
compounds in plants which, in turn, encourage plant vegetative growth. The increase in the fresh herbage
yield with <strong>nitrogen</strong> fertilization is in agreement with results reported were recorded by Agamy (2004);
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Said-Al Ahl (2005); Mauyo et al. (2008). The results in Table (1) show that plant growth is a function <strong>of</strong>
nutrients supply providing, there were clear significantly positive trend in increasing herb fresh yield by
spraying <strong>of</strong> <strong>potassium</strong> <strong>humate</strong>. Similar results were reported by Zaghloul et al. (2009) they indicated that
spraying Thuja orientalis plants with humic acid increased growth compared with control plants due to the
direct effect <strong>of</strong> humic acid on solubilization <strong>and</strong> transport <strong>of</strong> nutrients. These results are in accordance with
those obtained by Norman et al (2004) on marigolds <strong>and</strong> peppers <strong>and</strong> number <strong>of</strong> fruits <strong>of</strong> strawberries.
Chen <strong>and</strong> Avaid (1990) added that humic substances have a very pronounced influence on the growth <strong>of</strong>
plant roots <strong>and</strong> enhance root initiation <strong>and</strong> increased root growth which known root stimulator. Humic acid
improve growth <strong>of</strong> plant foliage <strong>and</strong> roots. Vaughan (1974) proposed that humic acids may primarily
increase root growth by increasing cell elongation or root cell membrane permeability, therefore increased
water uptake by increased plant roots, <strong>and</strong> added that it can produce root systems with increased branching
<strong>and</strong> number <strong>of</strong> fine roots, as a result potentially increase nutrients uptake by increase root surface area
(Rauthan <strong>and</strong> Schnitzer, 1981).
The interaction effect was significant in both cuts <strong>of</strong> both seasons. The highest values <strong>of</strong> plant fresh weight
were produced from the treatment irrigated every 3 days <strong>and</strong> sprayed with 1% <strong>potassium</strong>-<strong>humate</strong>, followed
by the treatment irrigated every 3 days <strong>and</strong> sprayed with 1% <strong>potassium</strong>-<strong>humate</strong> <strong>and</strong> fertilized with 1.2 g N
pot -1 at the two cuts in both seasons.
Essential oil production:
In both cuts in both seasons, irrigation intervals, <strong>potassium</strong>-<strong>humate</strong>, <strong>nitrogen</strong> application <strong>and</strong> their
interaction affected the percentage <strong>of</strong> essential oils in oregano (Table 1). The mean values <strong>of</strong> essential oils
due to irrigation intervals treatments showed that increasing the period <strong>of</strong> irrigation from 7 to 5 days
increased essential the percentage <strong>of</strong> oils. Increasing the period <strong>of</strong> irrigation from 3 to 5 days increased
percentage <strong>of</strong> essential oils. In other words, the irrigation <strong>of</strong> oregano plants every 5 days accelerated the
production <strong>of</strong> essential oils, while the severe stress conditions due to irrigated every 7 days decreased the
biosynthesis <strong>of</strong> the essential oils. Similar results were recorded by Singh et al. (1997) <strong>and</strong> Fatima et al.
(2000). The mean values <strong>of</strong> essential oils due to <strong>nitrogen</strong> application at 0.6 g N pot -1 <strong>and</strong> 1.2 g N pot -1
increased in both cuts <strong>of</strong> both seasons. Nitrogen fertilization might enhance the essential oil biosynthesis
processes through its direct or indirect role in plant metabolism resulting in more plant metabolites. These
finding are in agreement with those <strong>of</strong> Omer (1998) <strong>and</strong> Omer et al. (2008), who said that <strong>nitrogen</strong> <strong>fertilizer</strong>
was effective in increasing essential oil <strong>of</strong> Origanum syriacum <strong>and</strong> Ocimum americanum, respectively.
Essential oil percent in oregano fresh herb were significantly affected as a result <strong>of</strong> foliar application with
K-<strong>humate</strong> (Table 1). Zaghloul et al. (2009) reported that <strong>humate</strong> application lead to increase oil content in
Thuja orientalis. From the above mentioned results, it could be concluded that foliar application <strong>of</strong> K-
<strong>humate</strong> promoted growth <strong>and</strong> possessed the best oil percentage in oregano plant. Generally, the maximum
essential oil content was observed in the fresh herb <strong>of</strong> plants that irrigated every 5 days <strong>and</strong> sprayed with
1% K-<strong>humate</strong> <strong>and</strong> fertilized with 1.2 g N pot -1 in the two cuts.
The oil yield <strong>of</strong> oregano (ml plant -1 ) was affected by irrigation intervals, <strong>potassium</strong> <strong>humate</strong> <strong>and</strong>/or <strong>nitrogen</strong>
fertilization in both cuts <strong>of</strong> both seasons. Decreasing the period <strong>of</strong> irrigation from 7 to 5 days increased oil
yield in both cuts <strong>of</strong> both seasons. Increasing irrigation intervals from 3 to 5 days increased oil yield in both
cuts <strong>of</strong> both seasons. Moisture stress also decreased fresh herb yield, so there was a decrease in oil yield
with an increase in moisture stress. These findings agree with those <strong>of</strong> Singh <strong>and</strong> Ramesh (2000) <strong>and</strong>
Zehtab- Salmasi et al. (2001). They found that water deficit decreased the oil yield <strong>of</strong> rosemary
(Rosmarinus <strong>of</strong>ficinalis L.) <strong>and</strong> anise (Pimpinella anisum L.), respectively. Increasing <strong>nitrogen</strong> doses
resulted in gradual <strong>and</strong> significant increase in essential oil yield in both cuts <strong>of</strong> both seasons. The higher the
amount <strong>of</strong> the <strong>nitrogen</strong>, the higher was the oil yield. The response <strong>of</strong> volatile oil content to <strong>nitrogen</strong>
fertilization might be attributed to de novo meristemic cell metabolism in building dry matter with essential
oil production. These results agree with those <strong>of</strong> Omer (1998) <strong>and</strong> Omer et al. (2008), who found a positive
correlation between <strong>nitrogen</strong> <strong>fertilizer</strong> <strong>and</strong> essential oil content in herbage <strong>of</strong> Origanum syriacum <strong>and</strong>
Ocimum americanum, respectively in all cuttings. In addition, spraying oregano plants with K-<strong>humate</strong>
caused an increase in the essential oil yield (Table 1). Generally, the highest essential oil yield (ml plant -1 )
was obtained from plants irrigated every 5 days <strong>and</strong> fertilized with 1.2 g N pot -1 <strong>and</strong> sprayed at 1% K-
<strong>humate</strong> in both cuts <strong>of</strong> both seasons.
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Chemical composition <strong>of</strong> essential oil:
To study the effect <strong>of</strong> irrigation intervals, K-<strong>humate</strong> <strong>and</strong>/or <strong>nitrogen</strong> fertilization on the main constituents <strong>of</strong>
the essential oil, the oil <strong>of</strong> each treatment was separately subjected to gas liquid chromatography <strong>and</strong> the
main compounds <strong>and</strong> their relative percentages are shown in (Table 2). Carvacrol, a phenolic compound,
was found to be the first major compound <strong>and</strong> ranged from 61.65 to 73.61%. Its maximum content was
observed in the essential oil <strong>of</strong> the herb that received 0.6 g N pot -1 with sprayed at 1% K-<strong>humate</strong> <strong>and</strong>
irrigated every 5 days in the second cut, while the minimum content was recorded with plants that received
1.2 g N pot -1 with sprayed at 1% K-<strong>humate</strong> <strong>and</strong> irrigated every 3 days. The second main compound was
identified as the monoterpine, P-cymene, which ranged from its maximum content (18.27%) with irrigated
every 3 days <strong>and</strong> received 1.2 g N pot -1 <strong>and</strong> sprayed at 1% K-<strong>humate</strong> in the second cut to its minimum
relative percent (6.80%) with irrigated every 5 days <strong>and</strong> fertilized at 0.6 g N pot -1 with sprayed at 1% K-
<strong>humate</strong> in the first cut. Generally, the main differences were observed with the two phenolic compounds
carvacrole <strong>and</strong> thymol, <strong>and</strong> their hydrocarponic precursor's terpinene <strong>and</strong> p-cymene. The phenolic
compounds increase in hot seasons at the expense <strong>of</strong> their preceding precursors. In other words, the relative
percentage <strong>of</strong> carvacrol was higher in the second cut than in the first cut. This may be attributed to the
effect <strong>of</strong> the environmental factors especially non-edaphic factors, since these plants grew in summer
months under high temperatures <strong>and</strong> received more solar energy than those grown in the spring summers.
These conditions accelerate the transformation <strong>of</strong> terpinene <strong>and</strong> p-cymene to phenolic compounds. These
findings agree with those <strong>of</strong> Omer (1998) on Origanum syriacum <strong>and</strong> Omer et al. (1994) on marjoram. In
this respect, Picacaglia <strong>and</strong> Marotti (1993) reported that during their two–year study differences in relative
amounts <strong>of</strong> thymol, carvacrol, γ–terpinene, <strong>and</strong> p-cymene, essential oils <strong>of</strong> Satureja montana which is
grown in Italy, could be attributed to the effects <strong>of</strong> environmental conditions.
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Table 1. <strong>Effect</strong> <strong>of</strong> <strong>potassium</strong> <strong>humate</strong> <strong>and</strong> /or <strong>nitrogen</strong> <strong>fertilizer</strong> under different irrigation
intervals on herb <strong>and</strong> essential oil <strong>of</strong> Origanum vulgare L. plant in 2006/2007 <strong>and</strong>
2007/2008 seasons.
Treatments
Fresh weight g plant -1 Essential oil % Essential oil yield (plant -1 )
First cut
Season 1 Season 2 Season 1 Season 2 Season 1 Season 2
I-3 8.90 a ± 2.187 8.72 a ± 2.173 0.59 b ± 0.049 0.59 b ± 0.051 0.05 b ± 0.016 0.05 b ± 0.017
I-5 8.20 b ± 2.140 8.35 b ± 2.263 0.66 a ± 0.084 0.66 a ± 0.074 0.06 a ± 0.020 0.06 a ± 0.020
I-7 5.97 c ± 1.461 5.90 c ± 1.498 0.58 b ± 0.075 0.57 c ± 0.083 0.04 c ± 0.012 0.04 c ± 0.013
LSD at 0.05 0.1585 0.1466 0.0257 0.0211 0.0025 0.0026
N0 5.03 e ± 0.825 5.00 e ± 0.874 0.51 d ± 0.058 0.51 e ± 0.068 0.03 e ± 0.005 0.03 e ± 0.005
N 1 5.98 d ± 1.082 5.94 d ± 1.115 0.57 c ± 0.043 0.56 d ± 0.042 0.04 d ± 0.007 0.03 d ± 0.010
N 2 6.67 c ± 1.105 6.45 c ± 1.024 0.59 c ± 0.046 0.60 c ± 0.050 0.04 c ± 0.009 0.04 c ± 0.009
H 9.73 a ± 1.614 9.69 a ± 1.647 0.64 b ± 0.060 0.64 b ± 0.049 0.06 a ± 0.012 0.06 ab ± 0.013
N 1 +H 9.17 b ± 1.712 9.32 b ± 1.743 0.66 ab ± 0.049 0.66 ab ± 0.060 0.06 b ± 0.015 0.06 b ± 0.015
N 2 + H 9.55 a ± 1.698 9.55 a ± 1.662 0.68 a ± 0.057 0.68 a ± 0.043 0.07 a ± 0.013 0.07 a ± 0.013
LSD at 0.05 0.2242 0.2073 0.0363 0.0298 0.0035 0.0036
I-3 x N0 5.89 i ± 0.157 5.90 h ± 0.100 0.53 ± 0.029 0.53 ± 0.058 0.03 e ± 0.000 0.03 g ± 0.000
I-3 x N 1 6.94 g ± 0.140 6.88 f ± 0.104 0.55 ± 0.000 0.57 ± 0.029 0.04 d ± 0.000 0.04 f ± 0.000
I-3 x N 2 7.75 e ± 0.195 7.15 def ± 0.132 0.58 ± 0.029 0.58 ± 0.029 0.05 c ± 0.006 0.04 f ± 0.000
I-3 x H 11.10 a ± 0.354 10.89 a ± 0.032 0.60 ± 0.050 0.60 ± 0.000 0.07 b ± 0.006 0.07 b ± 0.000
I-3 x N 1 +H 10.72 ab ± 0.135 10.67 ab ± 0.155 0.63 ± 0.029 0.62 ± 0.029 0.07 b ± 0.006 0.06 c ± 0.006
I-3 x N 2 +H 10.99 a ± 0.515 10.82 ab ± 0.076 0.65 ± 0.000 0.67 ± 0.029 0.07 b ± 0.000 0.07 ab ± 0.006
I-5 x N0 5.20 j ± 0.093 5.19 i ± 0.106 0.53 ± 0.058 0.55 ± 0.050 0.03 e ± 0.000 0.03 g ± 0.000
I-5x N 1 6.42 h ± 0.070 6.44 g ± 0.110 0.60 ± 0.050 0.60 ± 0.000 0.04 d ± 0.000 0.04 f ± 0.000
I-5 x N 2 6.99 fg ± 0.036 7.10 ef ± 0.179 0.63 ± 0.029 0.65 ± 0.000 0.05 c ± 0.006 0.05 d ± 0.000
I-5 x H 10.44 bc ± 0.445 10.67 ab ± 0.289 0.70 ± 0.050 0.70 ± 0.000 0.08 a ± 0.006 0.07 ab ± 0.006
I-5 x N 1 +H 9.84 d ± 0.151 10.26 c ± 0.405 0.72 ± 0.029 0.73 ± 0.029 0.07 b ± 0.000 0.08 a ± 0.006
I-5 x N 2 +H 10.30 c ± 0.263 10.47 bc ± 0.451 0.75 ± 0.000 0.73 ± 0.029 0.08 a ± 0.000 0.08 a ± 0.006
I-7x N0 4.02 l ± 0.067 3.92 k ± 0.104 0.45 ± 0.050 0.43 ± 0.029 0.02 f ± 0.000 0.02 h ± 0.000
I-7x N 1 4.58 k ± 0.181 4.51 j ± 0.400 0.55 ± 0.050 0.52 ± 0.029 0.03 e ± 0.006 0.02 h ± 0.000
I-7 x N 2 5.27 j ± 0.061 5.09 i ± 0.086 0.57 ± 0.058 0.57 ± 0.058 0.03 e ± 0.000 0.03 g ± 0.000
I-7 x H 7.65 e ± 0.150 7.50 d ± 0.095 0.62 ± 0.029 0.62 ± 0.029 0.05 c ± 0.000 0.05 de ± 0.006
I-7 x N 1 +H 6.95 g ± 0.138 7.03 ef ± 0.252 0.63 ± 0.029 0.63 ± 0.029 0.04 d ± 0.000 0.04 ef ± 0.006
I-7 x N 2 +H 7.37 ef ± 0.321 7.37 de ± 0.126 0.63 ± 0.029 0.65 ± 0.000 0.05 c ± 0.000 0.05 d ± 0.000
LSD at 0.05 0.3884 0.3590 N.S N.S 0.0060 0.0064
Means with different letters within each column are significant at 0.05 level <strong>and</strong> means in the
same column with the same letters are not significant. Mean ±Sd; Since: N = <strong>nitrogen</strong> <strong>fertilizer</strong>, i.
e. N0 = control, N1 = 0.6 g pot -1 , N2 = 1.2 g pot -1 ; I = Irrigation
Intervals, i. e. I-3; I-5, I-7 = irrigation every 3, 5 <strong>and</strong> 7 days; H= <strong>potassium</strong> <strong>humate</strong>
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Table 2. <strong>Effect</strong> <strong>of</strong> <strong>potassium</strong> <strong>humate</strong> <strong>and</strong> /or <strong>nitrogen</strong> <strong>fertilizer</strong> under different
irrigation intervals on herb <strong>and</strong> essential oil <strong>of</strong> Origanum vulgare L. plant in
2006/2007 <strong>and</strong> 2007/2008 seasons.
Treatments
Fresh weight g plant -1 Essential oil % Essential oil yield (plant -1 )
Second cut
Season 1 Season 2 Season 1 Season 2 Season 1 Season 2
I-3 10.39 a ± 2.506 10.46 a ± 2.505 0.57 b ± 0.039 0.57 b ± 0.046 0.06 a ± 0.017 0.06 a ± 0.019
I-5 9.88 b ± 2.392 9.66 b ± 2.510 0.60 a ± 0.068 0.60 a ± 0.071 0.06 a ± 0.021 0.06 a ± 0.021
I-7 7.25 c ± 1.849 7.32 c ± 1.854 0.54 c ± 0.066 0.54 c ± 0.054 0.04 b ± 0.013 0.04 b ± 0.012
LSD at 0.05 0.1827 0.1600 0.0195 0.0247 0.0025 0.0036
N0 6.01 d ± 0.986 5.81 e ± 0.993 0.49 d ± 0.049 0.50 d ± 0.050 0.03 d ± 0.009 0.03 c ± 0.007
N 1 7.25 c ± 1.637 7.33 d ± 1.465 0.53 c ± 0.026 0.54 c ± 0.042 0.04 c ± 0.009 0.04 b ± 0.009
N 2 8.01 b ± 0.877 7.97 c ± 0.894 0.56 b ± 0.049 0.55 c ± 0.043 0.05 b ± 0.007 0.04 b ± 0.007
H 11.30 a ± 1.782 11.36 a ± 1.752 0.61 a ± 0.046 0.59 b ± 0.042 0.07 a ± 0.015 0.07 a ± 0.015
N 1 +H 11.16 a ± 1.830 11.13 b ± 1.730 0.61 a ± 0.042 0.61 ab ± 0.053 0.07 a ± 0.013 0.07 a ± 0.014
N 2 + H 11.29 a ± 1.772 11.28 ab ± 1.773 0.63 a ± 0.036 0.63 a ± 0.043 0.07 a ± 0.016 0.07 a ± 0.015
LSD at 0.05 0.2583 0.2262 0.0276 0.0349 0.0036 0.0050
I-3 x N0 6.78 e ± 0.293 6.81 f ± 0.137 0.53 ± 0.029 0.53 ± 0.058 0.04 fg ± 0.000 0.03 d ± 0.006
I-3 x N 1 8.55 cd ± 0.150 8.64 d ± 0.456 0.53 ± 0.029 0.55 ± 0.050 0.05 de ± 0.006 0.05 b ± 0.006
I-3 x N 2 8.82 c ± 0.266 8.95 cd ± 0.050 0.57 ± 0.029 0.55 ± 0.050 0.05 cd ± 0.000 0.05 b ± 0.000
I-3 x H 12.78 a ± 0.247 12.85 a ± 0.218 0.60 ± 0.000 0.60 ± 0.000 0.08 a ± 0.000 0.08 a ± 0.000
I-3 x N 1 +H 12.64 a ± 0.456 12.70 a ± 0.267 0.58 ± 0.029 0.58 ± 0.029 0.07 b ± 0.006 0.08 a ± 0.006
I-3 x N 2 +H 12.75 a ± 0.259 12.83 a ± 0.208 0.62 ± 0.029 0.62 ± 0.029 0.08 a ± 0.000 0.08 a ± 0.000
I-5 x N0 6.49 e ± 0.452 6.02 g ± 0.126 0.50 ± 0.000 0.50 ± 0.000 0.03 hi ± 0.006 0.03 d ± 0.000
I-5x N 1 8.12 d ± 0.125 7.87 e ± 0.231 0.55 ± 0.000 0.55 ± 0.050 0.04 ef ± 0.006 0.04 bc ± 0.006
I-5 x N 2 8.32 d ± 0.186 8.06 e ± 0.110 0.60 ± 0.050 0.58 ± 0.029 0.05 cd ± 0.000 0.05 b ± 0.006
I-5 x H 12.15 b ± 0.327 12.17 b ± 0.289 0.65 ± 0.050 0.62 ± 0.029 0.08 a ± 0.000 0.08 a ± 0.006
I-5 x N 1 +H 12.05 b ± 0.333 11.80 b ± 0.265 0.65 ± 0.000 0.67 ± 0.029 0.08 a ± 0.000 0.08 a ± 0.006
I-5 x N 2 +H 12.14 b ± 0.356 12.04 b ± 0.063 0.67 ± 0.029 0.68 ± 0.029 0.08 a ± 0.006 0.08 a ± 0.000
I-7x N0 4.77 f ± 0.211 4.61 i ± 0.433 0.43 ± 0.029 0.47 ± 0.058 0.02 j ± 0.000 0.02 e ± 0.000
I-7x N 1 5.09 f ± 0.078 5.47 h ± 0.405 0.50 ± 0.000 0.52 ± 0.029 0.03 i ± 0.000 0.03 d ± 0.000
I-7 x N 2 6.90 e ± 0.095 6.90 f ± 0.100 0.52 ± 0.029 0.52 ± 0.029 0.04 gh ± 0.006 0.04 cd ± 0.006
I-7 x H 8.97 c ± 0.052 9.07 c ± 0.064 0.57 ± 0.029 0.55 ± 0.050 0.05 cd ± 0.000 0.05 b ± 0.000
I-7 x N 1 +H 8.78 c ± 0.338 8.90 cd ± 0.100 0.60 ± 0.050 0.57 ± 0.029 0.05 c ± 0.006 0.05 b ± 0.000
I-7 x N 2 +H 8.97 c ± 0.152 8.96 cd ± 0.064 0.60 ± 0.000 0.60 ± 0.000 0.05 cd ± 0.000 0.05 b ± 0.000
LSD at 0.05 0.4474 0.3919 N.S N.S 0.0062 0.0087
Means with different letters within each column are significant at 0.05 level <strong>and</strong> means in the
same column with the same letters are not significant. Mean ±Sd; Since: N = <strong>nitrogen</strong>
<strong>fertilizer</strong>, i. e. N0 = control, N1 = 0.6 g pot -1 , N2 = 1.2 g pot -1 ; I = Irrigation
Intervals, i. e. I-3; I-5, I-7 = irrigation every 3, 5 <strong>and</strong> 7 days; H= <strong>potassium</strong> <strong>humate</strong>
319

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Table 3. <strong>Effect</strong> <strong>of</strong> <strong>potassium</strong> <strong>humate</strong> <strong>and</strong> /or <strong>nitrogen</strong> <strong>fertilizer</strong> under
irrigation intervals on the constituents <strong>of</strong> Origanum vulgare L.in the
second season.
Compounds
1 st Cut 2 nd Cut
Treatments
T1 T2 T3 T1 T2 T3
pinene
-- -- -- -- -- --
pinene
-- --- 0.67 -- -- --
terpinene -- -- -- 0.41 0.20 0.22
P-cymene 11.74 6.80 13.81 11.31 11.79 18.28
limonene 1.19 2.86 0.40 0.20 1.31 --
γ- terpinene 7.60 12.81 8.74 10.28 2.64 5.07
linalool 0.25 0.17 0.34 0.17 -- 0.19
borneol -- 0.11 0.42 0.20 -- 0.16
Terpinene-4-
ol
0.93 0.19 0.51
0.27 0.18 0.18
terpineol 0.45 0.29 0.46 0.12 0.22 0.36
thymol 1.05 1.30 0.57 1.27 1.00 0.44
Bornyl acetate 0.25 0.61 0.34 -- 0.34 0.27
carvacrol 69.07 65.26 68.25 65.35 73.61 61.65
Carvacrol
acetate
0.18 0.16 0.64
0.89 0.20 0.21
elemene 0.18 0.18 0.56 0.14 0.24 0.13
caryophyllene
0.53 0.54 0.41 0.11 0.49 0.12
germacrene D 0.19 0.12 0.45 0.23 0.27 0.21
Identified
compounds
93.61 91.40 95.57
90.95 92.49 87.39
Unidentified
compounds
6.39 8.60 4.43
9.05 7.51 12.61
T1–irrigation every 7 days +<strong>potassium</strong> <strong>humate</strong>, T2– 0.6 gNpot-1 +<strong>potassium</strong>
<strong>humate</strong>+ irrigation every 5 days, T3– 1.2 gNpot-1+ irrigation every 3 days
+ <strong>potassium</strong> <strong>humate</strong>
CONCLUSIONS
Nitrogen <strong>fertilizer</strong> increase herb fresh yield <strong>and</strong> essential oil production under well-watered conditions
at 80% available soil moisture, also under moderate-watered conditions at 60% available soil moisture
<strong>and</strong> under water deficit conditions at 40% available soil moisture. Increasing irrigation levels increased
the production <strong>of</strong> oregano <strong>and</strong> the optimum irrigation levels for the highest yields <strong>of</strong> fresh herb <strong>and</strong>
essential oil was 80% available soil moisture. Supplying plants with a water level <strong>of</strong> 80% available soil
moisture <strong>and</strong> with 1.2 g N pot -1 (I-80%+ N3) gave the best result in case <strong>of</strong> herb fresh yield <strong>and</strong>
essential oil production.
320

Journal <strong>of</strong> Applied Sciences 2(3), 2009
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