4. ESTUDIO DEL MERCADO
4.2. PLAN DE MERCADO
JURICA, M. 1, PETŘÍKOVÁ, K.1
Key words: nutritional value, organic production, conventional production, Raphanus sativus L. var. niger (Mill.), Brassicca oleracea L. conv. botrytis (L.) Alef. var. italica Plenck
Abstract
This study attempted to measure the nutritional value of broccoli and radish grown by both organic and conventional methods. The trial took place in ČZU Prague- Trója. Broccoli and radish were grown at two diff erent planting spaces, autumn culture in 2007 and spring culture in 2008. Levels of anti-oxidants (carotenoids, vitamin C) were measured, together with the levels of cations. The results have been evaluated statistically. The nutritional value of broccoli and summer radish is infl uenced mostly by the growing period (spring or autumn). The increase of nutritional value by the ecological way of growing was found out just in the content of carotenoids, however not signifi cantly. The study continues.
Introduction
In recent years, people in the more developed countries have started to take in interest in the nutritional value of their food, including fruit and vegetables. This interest is not confi ned to just nutritional and rational nutrition specialists, but is also shared by consumers. Nutritional value is infl uenced not just by the botanical species but also by the growing method, or agricultural system. This raises the question of what eff ect organic growing methods have on nutritional value. In this article are reported the outcomes of nutritional values which were measured in summer radish and broccoli grown under the organical and conventional growing system.
Materials and Methods
The fi eld experiments were carried out on the organic and conventional trial fi elds of the Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague (ČZU). The preceding crop on both the organic and conventional plots was green manure (legumen cereals). The culture of broccoli (cv. “Belstar F1“) was sown in multipots on 10.07.2007 (harvested on 30.11.2007) and 28.02.2008 (similar cv. “Lucky F1“, harvested on 16.06.2008). The summer radish – Japanese hybrid variety – cv. Jarola F1 was sown directly on 15.08.2007 (harvested 22.10.2007) and on 26.03.2008 (harvested 02.06.2008). Two diff erent plant spacing were used. The experiment was replicated three times, each with an area of 10 m2.
Treatment of organic trial fi eld: Broccoli and summer radish were grown in compliance with the legal requirements and directives laid down for organic produce (Act No.242/2000). Immediately
after sowing of radish and planting of broccoli were usednon-woven textile covering. The preparation Ferramol Schneckenkorn was used in the broccoli against slugs.
Treatment of conventional trial fi eld: On the basis of the soil analysis, the conventional plot was fertilized with P, K and Mg. In the broccoli the herbicide Stomp 400SC was used to control the weeds, Sumithion Super and Karate were used against pests and Mesurol Schneckenkorn was used against slugs. In the summer radish Gramoxone was used before sowing and Pirimor, Decis 2,5 EC, and Actellic 50 EC were used against pests.
Analyses of nutritional value: Vitamin C was determined refl ectometrically by the RQ Flex method (Merck), mineral content by capillary isotachophoresis (Boček et al.,1986), and carotenoids by quantitative colorimetry (Holm, 1954).
Statistical evaluation was done by analysis of variance with determination of signifi cance at level P=0.05 with using of statistical program Unistat (version 4.5)
Results
Average values for the antioxidants – vitamin C and carotenoids – are in Table 1 (broccoli) and in Table 2 (summer radish). The content of vitamin C in broccoli, compared with the variants of organic and conventional production, was not signifi cantly diff erent. The content of vitamin C in both the organic and conventional plots was much lower in the autumn harvest of 2007 compared to the summer harvest in 2008. Similarly, levels of carotenoids in spring sown crops were higher than those sown in the autumn of 2007, under both growing systems, both organic and conventional. Vitamin C levels in summer radish were signifi cantly higher under the conventional growing system compared to the organical growing system, and also in spring culture in 2008. The levels of carotenoids showed a similar variation, but the results are not signifi cant.
Tab. 1: Levels of dry matter, vitamin C and carotenoids (in fresh matter) in organic and conventionally grown broccoli
Year/spacing (m) Dry matter (g.kg-1) Vitamin C (mg.kg-1) Carotenoids (mg.kg-1)
E K E K E K
2007 0,6 x 0,5 150 157 690 879 5,92 3,88
0,5 x 0,5 152 152 693 954 6,13 4,28
2008 0,6 x 0,5 98 100 758 753 15,07 13,92
0,5 x 0,5 91 105 823 783 13,85 15,08
Note: E- organic production, K- conventional production, 2007- autumn culture, 2008 spring culture Tab. 2: Levels of dry matter, vitamin C and carotenoids (in fresh matter) in organic and conventionally grownsummer radish
Year/spacing (m) Dry matter (g.kg-1) Vitamin C (mg.kg-1) Carotenoids (mg.kg-1)
E K E K E K
2007 0,20x0,35 65 73 147 181 0,66 0,53
0,30x0,35 70 77 165 198* 1,14 0,55
2008 0,20x0,35 62 66 189 248* 0,78 1,15
0,30x0,35 60 64 186 232* 0,52 1,01
The average content of minerals is shown in Tables 3 and 4. In broccoli the levelsof K were signifi cantly higher in autumn culture. In spring culture the levelswere signifi cantly higher under the conventional growing system. As with the broccoli, K levels in summer radish are aff ected by the growing period, but not signifi cant.
Sodium can have high levels in food, so a high value in vegetables is assessed negatively. Higher levels were found in broccoli grown under the organic system, butin summer radish thesituation was the opposite, althoughthe results are not conclusive. Broccolialso shown conclusive higher infl uence of spring growing term on higher Na content.
Organic broccoli grown in the autumn has lower levels of Ca. In summer radish was probative infl uence of the term of growing.
The content of Mg was signifi cantly higher in broccoli and also in summer radish in autumn culture, infl uence of variants was not conclusive.
Tab. 3: Levels of minerals in organic and conventionally grown broccoli (in fresh matter) Year/spacing (m) K (mg.kg-1) Na (mg.kg-1) Ca (mg.kg-1) Mg (mg.kg-1) E K E K E K E K 2007 0,6 x 0,5 5313 5189 96 69 225 253 349 391 0,5 x 0,5 5321 5282 86 74 218 346 366 317 2008 0,6 x 0,5 3637 4332* 295 164 296 273 227 222 0,5 x 0,5 3757 4000 228 167* 271 261 210 210
*signifi cantly diff erent (P=0,05) between organic and conventional production
Tab. 4: Levels of minerals in organic and conventionally grown summer radish (in fresh matter)
Year/spacing (m) K (mg.kg-1) Na (mg.kg-1) Ca (mg.kg-1) Mg (mg.kg-1) E K E K E K E K 2007 0,20x0,35 4037 3859 153 152 246 263 184 222 0,30x0,35 3563 3833 135 197 221 240 165 198 2008 0,20x0,35 3710 3439 163 177* 177 170 116 124 0,30x0,35 3608 3492 164 177* 176 171 118 132
*signifi cantly diff erent (P=0,05) between organic and conventional production
Discussion
Woese et al.(1995) evaluated 26 studies in which the content of vitamins in organically and conventionally grown vegetables were compared. With exception of leaf vegetables, there were no conclusive diff erences in the vitamin C content. In the same way Tauscher et al. (2003) and many others have shown that levels of vitamin C can be higher in organically grown leaf vegetables. However, in our experiments, higher levels were found in those grown conventionally. The lower levels vitamin C when autumn grown can be explained by the diff erences between cultivars, but also by the lower light intensity in the autumn. Decreased light intensity was higher in the organic growing, there were plants grown under textile covering. Seung (2000) and others argue that higher light intensity during the growing period increases the content of vitamin C in plants. The published literature usually states that the content of carotenoids is higher in
organic growing systems, for example, Leclerc et al. (1991) and Pither, Hall (1990). Higher levels of carotenoids in organic produce were observed in our experiments in the autumn and spring grown broccoli and in autumn sown summer radish. The diff erences of dry matter content between the two growing systems were not signifi cant. Mineral levels, such as Fe, K, Na and Mg, are mostly higher in organic crops (Tauscher et al. 2003, Knight 1990), but in our experiments the conclusive infl uence of the growing period was shown. The diff erences between the two growing systems (organic and conventional) were minimal. Similarly, plant density had no eff ect on the nutritional values of the plants.
Conclusions
From the evaluation of the chosen nutritional components – vitamin C, carotenoids and the mineral elements K, Ca, Mg and Na for the organic and conventional growing systems we can say that the nutritional value of broccoli and summer radish is infl uenced mostly by the growing period (spring orautumn). The increase of nutritional values by the ecological way of growing was found out just in the content of carotenoids. The study continues.
Acknowledgments
This work was supported by the MSM 435100002.
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