Muzeul Olteniei Craiova. Oltenia. Studii și comunic ări. Științele Naturii . Tom. 27, No. 12011 ISSN 1454-6914 [612069]

Muzeul Olteniei Craiova. Oltenia. Studii și comunic ări. Științele Naturii . Tom. 27, No. 1/2011 ISSN 1454-6914

29
INFLUENCE OF SOME ORGANIC FERTILIZERS ON THE PHYSIOLOGICAL
PROCESSES IN Citrullus lanatus (THUNB .) MATSUM . & NAKAI PLANTS
CULTIVATED IN AREAS WITH SANDY SOILS

NICOLAE Ion, LASCU Nicolae, PLOAE Marieta

Abstract. The physiological research was achieved in Citrullus lanatus (THUNB .) MATSUM . & NAKAI , Rica F1 hybrid, cultivated on
sandy soil, in field condi tions, at the CCDCPN, D ăbuleni, Dolj. The photosynthesis intensit y recorded, during the day, the highest
values at noon (12 a.m.) for watermelon plants fertilized with 30 t/ha Manure and the lo west values were recorded in the mornin g (8
a.m.) for plants fertilized with 30 t/ha Manure. The linear regressions performed between the photosynthesis rate and the
photosynthetic active radiation, show a strong positive corre lation to the plants ferti lized with 2 t/ha Orgevit (R2 = 0.96) and a weaker
positive correlation to the plants fertilized with 30 t/ha Manure (R2 = 0.51). The transpiration intensit y recorded the highest values at
noon (12 a.m.) for watermelon plants fertilized with 2 t/ha Orgevit and the lowest values in the morning (8 a.m.) for the plant s
fertilized with 30 t/ha Manure . The linear regressions performed between the photosynthetic rate active radiation and the
transpiration intensity of fertili zed plants, show a strong positiv e correlation to the plants fert ilized with 4 t/ha Orgevit ( R2 = 0.97)
and a weaker positive correlation to the plants fertilized with 60 t/ha Manure (R2 = 0.78). The mature leaves of watermelon plants
have the highest chlorophyll pigment content in plants fertilized with 2 t/ha Orgevit and the lowest content was recorded in pl ants
fertilized with 4 t/ha Orgevit.

Keywords: physiological processes, photosynthesis, transpiration, waterm elon plants, Orgevit.

Rezumat. Influența unor fertilizan ți organici asupra proceselor fiziologice la plantele Citrullus lanatus (THUNB .)
MATSUM . & NAKAI cultivate în zone cu soluri nisipoase. Cercetările fiziologice s-au efectuat la Citrullus lanatus (THUNB .)
MATSUM . & NAKAI , hibridul Rica F1, cultivate pe sol nisipos, în condi ții de câmp, la CCDCPN D ăbuleni, Dolj. Intensitatea
fotosintezei a înregistrat, pe parcursul zilei, cele mai mari valori la prânz (12 a.m.) la plantele de pepeni verzi fertilizate cu 30 t/ha
gunoi de grajd, iar cele mai mici valori diminea ța (8 a.m.) la plantele fertilizate cu 30 t/ha gunoi de grajd. Regresiile liniare realizate
între rata fotosintezei și radiația fotosintetic activ ă, evidențiază o corelație pozitiv ă puternică la plantele fertilizate cu 2 t/ha Orgevit
(R2 = 0,96) și o corela ție pozitiv ă mai slab ă la plantele fertilizate cu 30 t/ha gunoi de grajd (R2 = 0,51). Intensitatea transpira ției a
înregistrat cele mai mari valori la prânz (12 a.m.) la plantele de pepeni verzi fertilizate cu 2 t/ha Orgevit, iar cele mai mic i valori
dimineața (8 a.m.) la plantele fertilizate cu 30 t/ha gunoi de gr ajd. Regresiile liniare rea lizate între rata transpira ției și radiația
fotosintetic activ ă, la plantele fertilizate, eviden țiază o corelație pozitiv ă puternică la plante fertilizate cu 4 t/ha Orgevit (R2 = 0,97) și
o corelație pozitiv ă mai slabă la plantele fertilizate cu 60 t/ha gunoi de grajd (R2 = 0,78). La frunzele mature ale plantelor de pepeni
verzi cel mai ridicat con ținut în pigmen ți clorofilieni s-a înregistrat la plantele fertilizate cu 2 t/ha Orgevit, iar cel mai sc ăzut conținut
s-a înregistrat la plantele fertilizate cu 4 t/ha Orgevit.

Cuvinte cheie: procese fiziologice, fotosintez ă, transpira ție, plante de pepe ni verzi, Orgevit.

INTRODUCTION

This paper presents the results of the physiological research carried out on watermelon plants cultivated in
2009 at the Agricultural Station of Research and Development for the Pl ant Culture on Sandy Soils (CCDCPN)
Dăbuleni, Dolj. The physiological investig ations were carried out within the na tional research program (PN II), No.
52147/2008, entitled: "Research on the foundation and developm ent of technology for cultivation of watermelon grafted
plants, in order to obtain biological production in sandy soils areas".
Taking into account that watermelons are frequently cu ltivated on sandy soils, along with technological stages,
the fertilization is necessary for obtain ing quantitative and qualitative production. Th e sandy soils are co nsidered poorly
supplied in mineral substances and therefore in order to obta in biological watermelons, the organic fertilization of crops
is necessary, in accordance with the ru les of an ecological agriculture.
Organic manures can serve as alternative to mineral fertilizers (N AEEM et al., 2006) for improving soil
structure (D AUDA et al., 2008) and microbial biomass (S URESH et al., 2004).
The net photosynthetic activity is subjected to seasonal changes and to diurnal changes, which are mainly
influenced by the stage of shoot development, the leaf ageing, the accumulation of hormones and of carbohydrates in
the leaves, as well as by the fluctuations of light , leaf temperature, air temperature and humidity (L AKSO , 1985).
The photosynthetic CO 2 assimilation of the leaves was remarkably improved by high nitrogen nutrition
(CECHIN & FUMIS , 2004).
The young leaves have the highest intensity of the transpiration process and as they get older, the transpiration
intensity decreases, the lower values being recorded at senescent leaves (B URZO et al., 1999).

MATERIAL AND METHODS

Under the circumstances im posed by the biological agriculture, the behaviour of the Rica F1 watermelon
hybrid was studied in field condition. The Rica F1 soil is a late Sugar Baby cultivars type.

NICOLAE Ion LASCU Nicolae PLOAE Marieta

30
This paper presents the results of the physiological res earch obtained by applying the fertilization with Manure
and Orgevit in different doses of application.
The Manure is considered to be a natural fertilizer, full and complex, which comes from different animal
species from a mixture of straw, feed, manure and urine. It helps to improve the soil structure, the humus content and
the useful microorganisms.
The Orgevit is a granular organic fertilizer, which is ad ministered on the surface of the soil and it is then
incorporated in the land. The Orgevit contains: organic matter, nitrogen, phosphate, potassium, calcium, magnesium,
iron, manganese, zinc, molybdenum, cobalt, etc.
The watermelon plants on which physiological measurements were made were represented by the Rica F1
hybrid, cultivated on the following fertilization variants: plants fertilized with 30 t/ha Manure, plants fertilized with 60
t/ha Manure, plants fertilized with 2 t/ha Orgev it, plants fertilized with 4 t/ha Orgevit.
This paper's aim is to study physiological processes (photosynthesis rate, transpiration rate) of watermelon
plants in accordance with environmental factors.
The intensity of photosynthesis and transpiration were made by using the portable photosynthesis analyser,
LCpro+, system which enables automatic recording and other parameters (photosynthetic active radiations incident on
the leaf surface, leaf temperature, stomatal conductance, etc.).
The obtained results were graphically represented and statistically interpreted by using of the linear
regressions.
The content of the chlorophyll pigments was estimates by Minolta SPAD 502 chlorophyll meter (the use of the
chlorophyll meter SPAD is a non-destructive method and permits repeated measurements).

RESULTS AND DISCUSSIONS

The physiological investigations were carried out on July 7th 2009 and consisted of analysing the diurnal
dynamics of the physiological processes (photosynthesis rate, transpiration rate), of establishing correlations between
these processes and the intensity of photo synthetic active radiation incident on the leaf surface and also of determining
the chlorophyll pigment on Citrullus lanatus (THUNB .) MATSUM . & NAKAI , Rica F1 hybrid, in different organic
fertilization variants.
The morphological aspect of watermelon plants cultivated in different fertilization variants is shown in
figures 1-4.

Figure 1. Citrullus lanatus – plants fertilized with
30 t/ha Manure.
Figura 1. Citrullus lanatus – plante fertilizate cu
30 t/ha gunoi de grajd (original).

Figure 2. Citrullus lanatus – plants fertilized
with 60 t/ha Manure.
Figura 2. Citrullus lanatus – plante fertilizate
cu 60 t/ha gunoi de grajd (original).

Muzeul Olteniei Craiova. Oltenia. Studii și comunic ări. Științele Naturii . Tom. 27, No. 1/2011 ISSN 1454-6914

31

The diurnal dynamics of photosynthesis of the plants presents, generally, low values in the morning
correlated with low light and temperat ure intensity and with the reduced opening degree of the stomata, maximum
values at noon correlated with the increasing light intensity and temperat ure and with the opening degree of the stomata
and low values in the evening as a result of the decreasing light intensity, of the gradual decreasing temperature and of
the decreasing of the opening degree of the stomata (Figs. 5; 6).

8.8810.2724.12
14.6415.0916.98
051015202530
8 1 01 21 41 6 Plants Fertilized with 30 t/ha manure
Plants Fertilized with 60 t/ha manureμmol CO2/
m2 /sThe diurnal dynamics of photosynthesis
12.4423.89
13.96
11.6919.0519.52
051015202530
8 1 01 21 41 6
Plants Fertilized with 2 t/ha Orgevit
Plants Fertilized with 4 t/ha Orgevitμmol CO2/
m2 /sThe diurnal dynamics of photosynthesis
Hours

The diurnal dynamics of the transpiration of the plants presents low values in the morning correlated with
the minimum opening of the stomata and with the decreasing of the dehydration power of the air, maximum values in
the afternoon correlated with the increasing opening degree of the stomata as a result of the increasing light intensity
and temperature and of the dehydration po wer of the air, and low values towards the evening correlated with low light
intensity and temperature (Figs. 7; 8).

Figure 3. Citrullus lanatus – plants fertilized
with 2 t/ha Orgevit.
Figura 3. Citrullus lanatus – plante fertilizate
cu 2 t/ha Orgevit (original).

Figure 4. Citrullus lanatus – plants fertilized
with 4 t/ha Orgevit.
Figura 4 . Citrullus lanatus – plante fertilizate
cu 4 t/ha Orgevit (original).
Figure 5. The diurnal dynamics of photosynthesis in Citrullus
lanatus plants fertilized with 30 t/ha and 60 t/ha Manure.
Figura 5. Dinamica diurn ă a fotosintezei la plantele Citrullus
lanatus fertilizate cu 30 t/ha și 60 t/ha gunoi de grajd. Figure 6.The diurnal dynamics of photosynthesis in Citrullus
lanatus plants fertilized with 2 t/ha and 4 t/ha Orgevit.
Figura 6. Dinamica diurn ă a fotosintezei la plantele Citrullus
lanatus fertilizate cu 2 t/ha și 4 t/ha Orgevit.

NICOLAE Ion LASCU Nicolae PLOAE Marieta

32

2.884.24
3.574.91
2.91
3.38
0123456
81 0 1 2 1 4 1 6
Plants Fertilized with 30 t/ha manure
Plants Fertilized with 60 t/ha manureThe diurnal dynamics of transpiration
mmol H2O/
m2/ s
Hours

2.96.23
3.026.02
4.34
3.01
01234567
81 0 1 2 1 4 1 6Plants Fertilized with 2 t/ha Orgevit
Plants Fertilized with 4 t/ha Orgevitmmol H2O/
m2/ sThe diurnal dynamics of transpiration
Hours

The photosynthetic active radiations have a great role in the photosynthesis and transpiration induction by
carrying photoactive opening movements of the stomata and by increasing the temperature of the leaves. The intensity
of photosynthesis and transpiration varies depending on th e light radiation r eceived by leaves, which are dependent on
the position of leaves on plants.
The results obtained after the tests regarding the dynami cs of the photosynthetic active radiation incident on
the leaf surface of Rica F1 watermelon plants grown in different fertiliza tion variants are presented in table (Table 1).

Table 1. The photosynthetic active radiation incident on the leaf surface.
Tabel 1. Radia ția fotosintetic activ ă incidentă pe suprafa ța frunzei.

Watermelon plants cultivated
in different fertilization variants The photosynthetic active radiation ( μmol/m2/s)
Hours: 8 a.m. Hours: 12 a.m. Hours: 4 p.m.
Watermelon plants fertilized with 30 t/ha Manure 356 1678 1405
Watermelon plants fertilized with 60 t/ha Manure 897 1539 1325
Watermelon plants fertilized with 2 t/ha Orgevit 820 1488 510
Watermelon plants fertilized with 4 t/ha Orgevit 1148 1611 495

The linear regressions performed between the intensity of the photosynthesis and the photosynthetic active
radiation, show a strong positive correlation to watermelon pl ants fertilized with 2 t/ha Orgevit (the coefficient of
determination R2 = 0.96) and a weaker positive correlation to the plan ts fertilized with 30 t/ha manure (the coefficient of
determination R2 = 0.51) (Figs. 9; 10).

y = 0.0087x + 4.466
R2 = 0.5176y = 0.0033x + 11.465
R2 = 0.7431
051015202530
300 500 700 900 1100 1300 1500 1700 1900
Plants fertilized with 30 t/ha manure Plants fertilized with 60 t/ha manure
Linear (Plants fertilized with 30 t/ha manure ) Linear (Plants fertilized with 60 t/ha manure)The photosynhesis rate
μmol CO2/ m2 /s
The photosynthetic active radiation
μmol/m2/s Citrullus lanatus – Rica F1
y = 0.0122x + 5.2928
R2 = 0.9633
y = 0.0069x + 9.215
R2 = 0.7874
051015202530
300 600 900 1200 1500 1800
Plants fertilized with 2 t/ha Orgevit Plants fertilized with 4 t/ha Orgevit
Linear (Plants fertilized with 2 t/ha Orgevit) Linear (Plants fertilized with 4 t/ha Orgevit)The photosynhesis rate
μmol CO2/m2/s
The photosynthetic active radiation
μmol/m2/s Citrullus lanatus – Rica F1

Figure 7. The diurnal dynamics of transpiration in Citrullus
lanatus plants fertilized with 30 t/ha and 60 t/ha Manure.
Figura 7. Dinamica diurn ă a transpira ției la plantele Citrullus
lanatus fertilizate cu 30 t/ha și 60 t/ha gunoi de grajd. Figure 8. The diurnal dynamics of transpiration in Citrullus
lanatus plants fertilized with 2 t/ha and 4 t/ha Orgevit.
Figura 8. Dinamica diurn ă a transpira ției la plantele
Citrullus lanatus fertilizate cu 2 t/ha și 4 t/ha Orgevit.
Figure 9. The correlation between the intensity of the
photosynthesis and the leaf temperature in Citrullus lanatus plants
fertilized with 30 t/ha and 60 t/ha Manure.
Figura 9. Corela ții între intensitatea fotosintezei și temperatura
frunzei la plantele Citrullus lanatus fertilizate cu 30 t/ha și 60 t/ha
gunoi de grajd. Figure 10. The correlation between the intensity of the
photosynthesis and the leaf temperature in Citrullus lanatus
plants fertilized with 2 t/ha and 4 t/ha Orgevit.
Figura 10. Corela ții între intensitatea fotosintezei și temperatura
frunzei la plantele Citrullus lanatus fertilizate cu 2 t/ha și 4 t/ha
Orgevit.

Muzeul Olteniei Craiova. Oltenia. Studii și comunic ări. Științele Naturii . Tom. 27, No. 1/2011 ISSN 1454-6914

33
The linear regressions performed betw een the intensity of the transpiration and the photosynthetic active
radiation show a strong positive correlation to watermelon pl ants fertilized with 4 t/ha Orgevit (the coefficient of
determination R2 = 0.97) and a weaker positive correlation to the pl ants fertilized with 60 t/ha Manure (the coefficient
of determination R2 = 0.78) (Figs. 11; 12).

y = 0.0028x + 0.1891
R2 = 0.7809y = 0.0009x + 2.5025
R2 = 0.9021
012345
300 600 900 1200 1500 1800
Plants fertilized with 30 t/ha manure Plants fertilized with 60 t/ha manure
Linear (Plants fertilized with 60 t/ha manure) Linear (Plants fertilized with 30 t/ha manure)The transpiration rate
mmol H2O/m2/s
The photosynthetic active radiation
μmol/m2/sCitrullus lanatus- Rica F1
y = 0.0036x + 0.7117
R2 = 0.8843
y = 0.0027x + 1.5783
R2 = 0.973
01234567
400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700
Plants fertilized with 2t/ha Orgevit Plants fertilized with 4 t/ha Orgevit
Linear (Plants fertilized with 2t/ha Orgevit) Linear (Plants fertilized with 4 t/ha Orgevit)The photosynthetic active radiation
μmol/m2/sCitrullus lanatus – Rica F1 The transpiration rate
mmol H2O/m2/s

The temperature along with the solar radiation intensity is th e main external factor which influences the
photosynthesis and transpiration processes. The temperature of the plants generally depends in a large measure on the ambient air temperature, and on th e transpiration intensity, which limit the temperature of the plants.
The research carried out on the dynamics of air temper ature at the time of the physiological tests, show a
temperature increase in the morning (8 a. m.) when the values are of 27.9 °C, an increase at noon (12 a.m.) when the
values are of 35.1 °C and a slight decrease in the evening (4 p.m.) when the values are of 31.5 °C.
The chlorophyll content. The mature leaves of watermelon plants grown in different fertilization alternatives
have the highest chlorophyll pigment content in plants fertilized with 2 t/ha Orgevit and the lowest content was
recorded in plants fertilized with 4 t/ha Orgevit (Fig. 13).

4746.747.5
45.3
3035404550
Plants Fertilized with
30 t/ha ManurePlants Fertilized with
60 t/ha ManurePlants Fertilized with
2 t/ha OrgevitPlants Fertilized with
4 t/ha OrgevitThe chlorophyll content in mature leaves
SPAD units

Figure 11. The correlation between the intensity of the
transpiration and the leaf temperature in Citrullus lanatus plants
fertilized with 30 t/ha and 60 t/ha Manure .
Figura 11. Corela ții între intensitatea transpira ției și temperatura
frunzei la plantele Citrullus lanatus fertilizate cu 30 t/ha și 60
t/ha gunoi de grajd. Figure 12. The correlation between the intensity of the
transpiration and the leaf temperature in Citrullus lanatus plants
fertilized with 2 t/ha and 4 t/ha Orgevit .
Figura 12. Corela ții între intensitatea transpira ției și temperatura
frunzei la plantele Citrullus lanatus fertilizate cu 2 t/ha și 4 t/ha
Orgevit.
Figure 13. The chlorophyll content at the mature leaves of Citrullus lanatus.
Figura 13. Con ținutul în clorofil ă la frunzele mature de Citrullus lanatus .

NICOLAE Ion LASCU Nicolae PLOAE Marieta

34
CONCLUSIONS

During the day the highest values of the photosynthesis intensity were recorded at noon (12 a.m.) for
watermelon plants fertilized with 30 t/ha Manure (24.12 µmol CO 2/m2/s) and the lowest values were recorded in the
morning (8 a.m.) for the plants fertili zed with 30 t/ha Manure (8.88 µmol CO 2/m2/s).
The linear regressions performed between the photosynthesis rate and the photosynthetic active radiation show
a strong positive correlation to the plants fertilized with 2 t/ha Orgevit (R2 = 0.96) and a weaker positive correlation to
the plants fertilized with 30 t/ha Manure (R2 = 0.51).
During the day the highest values of the transpiration in tensity were recorded at noon (12 a.m.) for watermelon
plants fertilized with 2 t/ha Orgevit (6.23 mmol H 2O/m2/s) and the lowest values were recorded in the morning (8 a.m.)
for the plants fertilized with 30 t/ha Manure (2.88 mmol H 2O/m2/s).
The linear regressions performed between the transpiration rate and the photosynthetic active radiation show a
strong positive correlation to the plants fertilized with 4 t/ha Orgevit (R2 = 0.97) and a weaker positive correlation to the
plants fertilized with 60 t/ha Manure (R2 = 0.78).
The mature leaves of watermelon plants have the highes t chlorophyll pigment content in plants fertilized with
2 t/ha Orgevit and the lowest content was recorded in plants fertilized with 4 t/ha Orgevit.

REFERENCES

BURZO I., TOMA S., OLTEANU I., DEJEU L., DELIAN ELENA , HOZA D. 1999. Fiziologia plantelor de cultur ă.
Întreprinderea Editorial Poligrafic ă Știința. Chișinău. 3: 440 pp.
CECHIN I. & FUMIS T. D. 2004. Effect of nitrogen supply on growth and photosynthesis of sunflower plants grown in
the greenhouse . Plant Science. 166: 1379-1385.
DAUDA S. N., AJAYI F. A., NDOR E. 2008. Growth and yield of water melon (Citrullus lanatus) as affected by poultry
manure application . Journal of Agriculture and Social Science. 4: 121-124.
LAKSO A. N. 1985. The effects of water stress potential on physiological processes in fruit crops . Acta Horticulturae
(ISHS). 171: 275-290.
NAEEM M., IQBAL J., BAKHSH M. A. A. 2006. Comparative study of inorganic fertilizers and organic manures on yield
and yield components of mungbean (Vigna radiate L.) . Journal of Agriculture and Social Science. 2: 227-229.
SURESH K. D., SNEH G., KRISHN K. K, MOOL C. M. 2004. Microbial biomass carbon and microbial activities of soils
receiving chemical fertilizers and organic amendments . Archives Agronomy Soil Science. 50: 641-647.

Nicolae Ion, Lascu Nicolae
University of Craiova, No. 13, A. I. Cuza Street,
200585, Craiova, Romania
E-mail: ionnicolaebio@yahoo.com
E-mail: lascu_nicolae@yahoo.com

Ploae Marieta
CCDCPN D ăbuleni, Dolj, Romania
E-mail: marietaploae@yahoo.com
Received: March 30, 2011
Accepted: August 2, 2011