Romanian Biotechnological Letters Vol. 16, No.1, 2011, Supplement Copyright © 2011 University of Bucharest Printed in Romania. All rights reserved

ORIGINAL PAPER

26

Research regarding the influence of laser radiation upon the growth and development of some vegetable species (eggplant and sweet pepper)

Received for publication, October 27, 2010

Accepted, January 21, 2011

FLOAREA BURNICHI1, MARIA-GABRIELA PÂRVU1, SILVANA DANAILA-GUIDEA2 , NICULIŢA PETRU2, ESOFINA RISTICI2, RISTICI MARIAN3 1 Research and Development Station for Vegetables Growing Buzau, Mesteacanului Street, no. 23, Buzau, 120024, Romania 2 University of Agronomic Sciences and Veterinary Medicine, Faculty of Biotechnology, 59 Marasti Ave., 011464, Bucharest, Romania 3 4R OPTICS S.R.L., Telita Street, no. 3, sector 5, 051883, Bucharest, Romania

Abstract Within the framework of the experiments made throughout the year 2010 a model of ecologic and

stressless experimental treatment of vegetable transplants was made. This experiment based on a laser radiation field was applied to two vegetable species: eggplants (Solanum melongena L.) and sweet pepper (Capsicum annuum L.), using as irradiation source a 200 mW nominal power semiconductor laser device with continuous laser radiations. The necessary treatment dosage for the plants was calculated taking into account the distance from the irradiation source to the irradiated surface for transplants. There have been made observations and measurements regarding the evolution of morphological and biological parameters of vegetable plants during the vegetation period and also regarding the influence of laser irradiation treatment upon their growth, development and dynamic crop production. Statistical processing of the results indicated significant differences regarding the plants' size, growth rhythm, development and crop production.

Key words: vegetables, laser radiation, unstressful ecologic model, plant growth

Introduction Living organisms are open systems that interact with the environment (receive and

dispense information, energy and substance), being constantly under the influence of low-intensity electromagnetic fields. Adverse environmental conditions, increased cloudiness, pollution, results in a lower recovery of solar radiation by plants. . This is reflected in lower productivity and lower resistance of plants. As a result, plants need a larger amount of energy produced per unit of fresh substance. Laser radiation interaction with biological environment has specific features due to laser radiation characteristics, this study involving physical and biological aspects. (Anghel S. şi col., 1999 [1], Calugareanu M. şi col. 1999 [2], Chiţa Anca Monica, 2004 [3]). Many authors emphasize the importance of red light in plant photosynthetic activity. (G. Vasilevski, D. Bosev, 1997 [4]). In experiments conducted with continuous laser light and laser light modulated at audio frequencies (P. Niculiţa şi col. 2006 [5]), was found that when laser radiation is further conventional radiation, sufficient doses of up to 2 J/cm2 for plant irradiation with effects on plants.

The purpose of this experiment was to determine the effect of laser beam irradiation on biological material (seedlings) and the influence of this treatment on growth and subsequent development in culture, of two species of vegetable, sweet peppers and eggplants. This may open new avenues in vegetable research, allowing synchronous modulated laser light use as organic and non-stressful stimulus of growth.

Material and method

In 2010, the Station of Vegetable Research and Development in Buzau, within research

contract no. 52-136/2008 the irradiation experiments were conducted in the early stages of

FLOAREA BURNICHI, MARIA-GABRIELA PÂRVU, SILVANA DANAILA-GUIDEA , NICULIŢA PETRU, ESOFINA RISTICI, RISTICI MARIAN

Romanian Biotechnological Letters, Vol. 16, No. 1, Supplement (2011) 27

plant development (seedlings) with modulated fields of laser radiation and monitoring of the effects of these treatments during the growing season. In the second experiment there were chosen species of vegetable plants, sweet pepper (Capsicum annuum L.) variety "Buzau 10" and eggplant (Solanum melongena L.), variety "Dragaica", creations of the research team from SCDL Buzau. Irradiation was done with a diode laser irradiation device comprising: laser head, clamping support - mobile arm system, power feeders (Fig. 1).

Figure 1. Diode laser irradiation device

Laser head consists of 19 laser diodes in a cylinder aligned so that light from them to overlap so as to generate a uniform illumination on the surface of exposure. Clamping system type "mobile arm" allows you to adjust the distance between laser diode system and exposure area. The device is independent and can sit on a surface where it can be exposed plants to be treated. Exposed surface is chosen according to the size of plants to be irradiated and can be adjusted with the mobile arm. Power Supply is at plug of 220V and 50 Hz c.a.

Five different experiments were established with various doses of radiation, compared with untreated control. Time source of radiation exposure and height varied in correlation with plant height (Table 1). Table 1. Treatment dose and exposure time depending on the area irradiated

Species Capsicum annuum L. Solanum melongena L.

Var. Irradiation dose j/cm2

The average height of the package plant

cm

Number of leaves /

plant

The average of min exposure

time

The average height of the package plant

cm

Number of leaves /

plant

The average of min exposure

time

V1 Witness 21.33 9.13 - 19.05 5.57 - V2 0.02 17.90 8.03 1.00 19.60 5.60 1.00 V3 0.04 20.75 9.53 2.00 19.57 5.53 2.00 V4 0.08 19.92 9.17 4.07 18.88 5.53 3.97 V5 0.16 20.22 9.27 8.13 19.33 5.33 7.33 V6 0.30 18.95 8.80 15.30 19.33 5.73 15.33

Calculation example: For a dose of 1.2 J/cm2, initially chosen, the lighting time for an

area of 50 cm2 was of 10 minutes, while an area of 100 cm2 was of 20 minutes, and for 200 cm2 exposure time reached even to 40 minutes. Seedlings were irradiated with doses up to 0.3 J/cm2 achieving some results statistically.

A assumed that laser biostimulation could have positive effects on plant development with measurable results: the percentage of holding, the rythm of development, plant height, number of tillers issued, harvest obtained and fruit quality.

Research regarding the influence of laser radiation upon the growth and development of some vegetable species (eggplant and sweet pepper)

28 Romanian Biotechnological Letters, Vol. 16, No. 1, Supplement (2011)

Irradiated seedling was planted in the experimental field of SCDL Buzau, in randomized blocks, in six variants of four repetitions, each variant totaling an area of 24 m2. Maintenance works were carried out according to conventional technology. Experimental plots were established on 15.06.2010 and observations and measurements were made on biometric variations and repetitions by the end of the growing season.

Results and discussions

The data collected were processed and statistical interpretation of results was obtained.

The results are presented both as values and as the percentage of deviation, between the variants irradiated by laser and variant untreated.

Table 2 summarizes the numerical values obtained experimentally on the growth dynamics of strains and changes in the number of shoots formed in the studied vegetables species: sweet pepper (Capsicum annuum L.) variety „Buzau 10” and eggplants (Solanum melongena L.), variety „Dragaica”, on the variations of radiation, compared with witness version (V1). Table 2 - Influence of irradiation dose on the dynamics of stem growth and number of shoots formed (15.06.2010-28.09.2010)

Species Capsicum annuum L. Solanum melongena L. Variant (j/cm2) Date Dynamics of

stem growth cm Number of

shoots Dynamics of

stem growth cm Number of

shoots V1 - Witness 34.03 6.2 91.68 2.9 V2 - 0.02 37.47 4.8 91.13 3.1 V3 - 0.04 34.62 5.7 91.17 2.9 V4 - 0.08 35.45 5.7 91.85 3.5 V5 - 0.16 35.15 4.9 91.40 3.3 V6 - 0.30

28.09. 2010

36.42 5.0 91.40 2.9

The sweet pepper species (Capsicum annuum L.) variety „Buzau 10” as a result of treatment with laser radiation it was registered a significantly decreasing of the average number of shoots formed from 6.2 shoots / plant in witness variant (V1) at 4.8 shoots / plant at V2 (0.02 j/cm2), at 4.9 shoots / plant at V5 (0.16 j/cm2) and respective 5 shoots / plant at V6 (0.30 j/cm2) (Table no. 3) Table 3. Average number of shoots / plant - sweet pepper “Buzau 10”

AVERAGE NUMBER OF

SHOOTS NR.

CRT. Variant Irradiation

dose j/cm2

AVERAGE NUMBER

OF SHOOTS RELATIVE %

DIFFERENC

E

t

P%

SEMNIFICATION

1 V1 Witness 6.20 100.00 0.00 - 2 V2 0.02 4.80 77.42 -1.40 -2.96 1.33 0 3 V3 0.04 5.73 92.47 -0.47 -0.99 34.10 4 V4 0.08 5.73 92.47 -0.47 -0.99 34.10 5 V5 0.16 4.93 79.57 -1.27 -2.68 2.30 0 6 V6 0.3 5.00 80.65 -1.20 -2.54 3.10 0

Average number of shoots / plant DL5%: 2,23*0.472 1.05 shoots/plant 19.2% This reduction in the number of shoots was significantly positively correlated with

number of fruits formed and the total fruit production obtained (Table no. 4, graph no. 1), at V6 (0.3 j/cm2) registering increasing of 35.2% and of 13.21% at V2 ((0.02 j/cm2) against the witness (V1). At V5 was a negative correlation between the number of shoots formed, the average number of fruit harvested, respectively the total output produced (-12% fruit formed and -10.9% the total production compared with V1).

FLOAREA BURNICHI, MARIA-GABRIELA PÂRVU, SILVANA DANAILA-GUIDEA , NICULIŢA PETRU, ESOFINA RISTICI, RISTICI MARIAN

Romanian Biotechnological Letters, Vol. 16, No. 1, Supplement (2011) 29

Table 4 - Average number of fruits / plant - sweet pepper “Buzau 10” AVERAGE

NUMBER OF SHOOTS

Nr. crt. Variant

Irradiation dose j/cm2

AVERAGE NUMBER OF

SHOOTS RELATIVE %

DIFFERENCE

t

P%

SEMNIFICATION

1 V1 Witness 10.60 100.00 0.00 - 2 V2 0.02 12.00 113.21 1.40 1.10 29.70 3 V3 0.04 11.80 111.32 1.20 0.94 39.00 4 V4 0.08 10.67 100.63 0.07 0.05 92.00 5 V5 0.16 9.33 88.05 -1.27 -0.99 34.10 6 V6 0.3 14.33 135.22 3.73 2.93 1.60 x

Average number of fruits per plant DL5% 2,23*1.274 2.84 fruit 23.9%

Graph no. 1. Total production DL5% 2,23*6.321 14.10 t/ha 30.4%

Graph no. 2 shows the dynamics of harvesting during the growing season, with a relative production of 25.74% higher comparing to untreated witness.

Graph no. 2. Dynamics of production of fruit at sweet pepper during the vegetation (kg / plant)

At the species eggplant (Solanum melongena L.), variety "Dragaica" the laser treatment

resulted in changes in plant habitus, height, average number of shoots, average number of fruit harvested per plant and total output produced. Thus at V5 (0.16 j/cm2) the plant height

Dynamics of harvesting during the growing season – sweet pepper fruit production kg / plant

0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450

13. 08. 2010 1. 09. 2010 20.09.2010

kg

V1 V2 V3 V4 V5 V6

0.00

10.00

20.00

30.00

40.00

50.00

60.00

V1 V2 V3 V4 V5 V6

Total production – sweet pepper "Buzau 10" variety (t/ha)

Total production t / ha

Research regarding the influence of laser radiation upon the growth and development of some vegetable species (eggplant and sweet pepper)

30 Romanian Biotechnological Letters, Vol. 16, No. 1, Supplement (2011)

increased significantly, exceeding the 12% the witness V1, while the V6 (0.30 J/cm2) exceeded the witness with 10.2% (Table no. 5). Table 5. The average height of eggplants “Dragaica” (cm)

PLANT HEIGHT PLANT HEIGHT DIFFERENCE NR.

CRT.

Variant Irradiation dose j/cm2 cm RELATIVE% cm

t

P%

SEMNIFICATION

1 V1 Witness 110.73 100.00 0.00 - 2 V2 0.02 112.60 101.69 1.87 0.37 69.80 3 V3 0.04 107.87 97.41 -2.87 -0.56 56.20 4 V4 0.08 116.87 105.54 6.13 1.20 25.80 5 V5 0.16 124.00 111.98 13.27 2.60 2.70 x 6 V6 0.3 122.07 110.23 11.33 2.22 5.30

Plant height DL5% 2,23*5.108 11.39 cm 10.0%

The number of shoots increased significantly at V4 by 18.2% and at V5 with 11.4% compared with witness V1. In terms of average number of fruit harvested per plant and total production obtained the data are correlated, with a greater number of fruits per plant and total production increased significantly compared to untreated witness V1, at variants V3 (0.04 j/cm2), V5 (0.16 j/cm2) and V6 (0.30 j/cm2). At V3 and V5 the average number of fruits produced per plant increased by 20.9% and at V6 with 18.6%. Production growth rate recorded was of 31% at V3, 34.6% at V5 and 30.6% at V6 (Table no. 6 and Graph no. 3). There are also presented the differences as percentage limit (%) for all parameters determined in the two vegetables species taken in study. Table 6 - The average number of fruits /plant at eggplants “Dragaica”

AVERAGE NUMBER

OF SHOOTS NR.

CRT. Varian

t

Irradiation dose j/cm2

AVERAGE NUMBER

OF SHOOTS RELATIVE%

DIFFERENCE t

P%

SEMNIFICATION

1 V1 Witness 2.87 100.00 0.00 - 2 V2 0.02 3.27 113.95 0.40 1.90 8.70 3 V3 0.04 3.47 120.93 0.60 2.86 1.60 x 4 V4 0.08 3.27 113.95 0.40 1.90 8.70 5 V5 0.16 3.47 120.93 0.60 2.86 1.60 x 6 V6 0.3 3.40 118.60 0.53 2.54 3.10 x

Average number of fruits/ plant DL5% 2,23*0.210 0.47 14.4%

Graph no. 3. Total production DL5% 2,23*3.654 8.15 t/ha 24.4%

V1 V2 V3 V4 V5 V6

0.00 5.00

10.00 15.00 20.00

25.00 30.00

35.00 40.00

t/ha

Total production (t / ha) – "Dragaica" eggplants variety

Total production t/ha

FLOAREA BURNICHI, MARIA-GABRIELA PÂRVU, SILVANA DANAILA-GUIDEA , NICULIŢA PETRU, ESOFINA RISTICI, RISTICI MARIAN

Romanian Biotechnological Letters, Vol. 16, No. 1, Supplement (2011) 31

In graph no. 4 the dynamics of production of fruit harvested per plant, which graphically shows that variants V5 and V4 have registered a peak of accumulation of fresh substance of 0.5 kg / plant in the third harvest, while the V5 and V6 variants presented a relatively steady accumulation of dry fresh fruit throughout the harvesting period.

Sweet pepper varieties "Buzau 10" and eggplant "Dragaica" used as biological material in the experiments, were designed and patented at SCDL Buzau and they are registered in the "Official catalog of varieties of crop plants in Romania in 2010" (Fig. 2 and 3).

Figure 2. Sweet peppers „Buzau 10” Figure 3. Eggplants „Dragaica” Conclusions

Irradiation of the plants causes at the species studied, sweet pepper (Capsicum annuum

L.) variety "Buzau 10" and eggplant (Solanum melongena L.), variety "Dragaica", changes in plant size, number of shoots formed, significantly influencing both number of fruits formed per plant and total production obtained from organic and unstressful treatment applied.;

1. As a first result, at the sweet pepper variety "Buzau 10", all doses of irradiation used determined decreasing of plant height and reducing of the number of shoots formed, the percentage decrease ranging from 7.5% in V3 and V4 and 22.6% at V2, compared to witness variant V1.

2. For sweet pepper, variety "Buzau 10", the most effective dose of radiation proved to be V6 (0.30 j/cm2), followed by V2 (0.04 j/cm2), laser radiation therapy positively influences the total production and respective the number of fruit produced per plant formed (+35.2%),

Dynamics of harvesting during the growing season – eggplants fruit production kg / plant

0.000

0.100

0.200

0.300

0.400

0.500

0.600

11.08.2010 13. 08.2010 25.08.2010 01.09.2010 10.09.2010 28.09.2010

kg/pl

V1 V2 V3 V4 V5 V6

Research regarding the influence of laser radiation upon the growth and development of some vegetable species (eggplant and sweet pepper)

32 Romanian Biotechnological Letters, Vol. 16, No. 1, Supplement (2011)

production growth recorded being with 25.7% at V6, namely 12.5% at V2 regarding V1 witness untreated.

3. For sweet peppers, variety "Buzau 10" version of treatment with laser radiation V5 (0.16 j/cm2) resulted in a significant reduction in the number of shoots formed with 20.4%, of the number of fruits formed with 12% , aggregate production was lower by 10.9% compared to the witness untreated V1.

4. At the variety of eggplants „Dragaica” treatment option with the best results was V5 (0.16 j/cm2), which led to a significant production increase of 34.6% compared to the witness variant V1, increasing of number of fruit / plant with 20.9%, of plant size with 12% and of number of shoots formed with 11.4%.

5. At the eggplants "Dragaica" the effect of irradiation on V3 (0.04 J/cm2) has resulted in a slight reduction in plant size and number of shoots formed, but without statistical significance compared to witness V1..

6. Plant irradiation at eggplants "Dragaica" determined, for V3 (0.04 J/cm2) a significant increase of 31% to total production achieved, by 20.9% in the number of fruits per plant, as for V5 (0.15 j / cm2) results being given statistically.

7. For the eggplants variety "Dragaica" irradiation dose of 0.30 J/cm2 (V6) had a positive influence, leading to statistically significant production increases of 30.6%, a significant increase in the number of fruits per plant, with 18.6 % and of the plant height by 10.2% compared to the witness variant V1.

8. Radiation dose of 0.08 J/cm2 (V4) determined in the variety of eggplants "Dragaica" a significant increase in the number of shoots per plant by 18.2% compared to the untreated witness V1.

9. For sweet peppers and eggplants species treatment with laser radiation of plants in the V6 version (0.30 J/cm2), lead to significant positive differences in the total production and number of formed fruits / plant.

Research will continue to strengthen results and identify new treatment options with laser radiation and ecological unstressful stimulating effect of growth, plant development and that allows obtaining higher production quantitatively and qualitatively.

Acknowledgements This work belongs to a national research project, PN II 52-136/2008PLANTCAMP, funded by the National Ministry of Research by CNMP. References

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