Effect Of Organic Farming On Nutritional Profile Of Tomato Crop

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Author: Dr. K. Sreedevi Shankar and Dr.S. Sumathi

Effect Of Organic Farming On Nutritional Profile Of Tomato Crop

K.Sreedevi Shankarø and S.Sumathi øCentral Research Institute for Dryland Agriculture, Hyderabad, A.P-500 059 Post graduate and Research Centre, ANGRAU, Hyderabad, A.P-500 030

ABSRACT:

Tomato crop was grown using organic manures and chemical fertilizers and the effect of organic farming on nutritional profile, quality characteristics, toxic parameters were studied. The experiment was laid out in a randomized block design with fifteen treatments consisting of four organic manure treatments of vermicompost (VC), poultry manure (PM), farm yard manure (FYM), cow dung (CD) and recommended dose of chemical fertilizers i.e conventional farming as control. Organically and conventionally grown tomato were analysed for their nutrient composition. Application of organic manures was found to be significantly influence the nutrient content of these crops compared to conventional fertilizers. Key words : Organic farming, conventional fertilizers, tomato crop, nutritional quality. Tomato is the world's largest vegetable crop after potato and sweet potato. It is one of the most protective food. In terms of human diet, the tomato is a major component of daily meals in many countries and constitutes an excellent source of health-promoting compounds due to the balanced mixture of minerals and antioxidants including vitamin C, total carotene. The purpose of this paper is to show how the health-promoting compounds of tomato fruit may be improved through controlling conditions of production through organic farming. In the face of a global market economy and public awareness of health attributes of food, obtaining tomato fruit of very high health quality is essential for insuring health benefit and consequently consumer satisfaction. This study will then conclude on the better strategy to adopt for improvement of the health-promoting phytochemicals of tomato. Organically and conventionally grown tomato were analysed for their nutrient composition. Application of organic manures was found to significantly influence the nutrient content of these crops compared to conventional fertilizers.

Materials and Methods

Tomato crop was grown using organic manures and chemical fertilizers and the effect of organic farming on nutritional profile, quality characteristics and toxic parameters was studied. The experiment was laid in an unused land. The experimental design used was Randomized Block Design (RBD) with 5 treatments, and 4 replications each of organic manures i.e vermicompost (VC), farmyard manure (FYM), poultry manure (PM), cow dung (CD) and conventional farming as control. Tomato plots (Gross plot 240 m2 and Net plot 210 m2 (2x1.5 m2) were laid in four replications with the following treatments for each crop.

Tomato nursery raising Nursery beds were raised for tomato as per recommendations (Chadha, 2003). Organic manure was used to raise nursery beds to avoid contamination with chemical fertilizers. The nursery beds were treated with Trichoderma viridi and Pseudomonas fluorescence to protect seeds and seedlings from pests. Soon after sowing, the beds were irrigated everyday morning. Seedlings were ready for transplantation in one month after sowing. Before transplanting, the seedlings were treated with 0.1% Trichoderma viridi.

Manuring and fertilization of tomato Different organic manures and chemical fertilizers were applied to the plots as per recommendations [Vyavasaya panchagam 2005(ANGRAU)] Organic Manure (including moisture content): Vermicompost : 6.13 kg/ plot Farm yard manure : 11.43 kg/ plot Poultry manure : 7.03 kg/ plot Cow dung : 15.29 kg/ plot Chemical Fertilizers :(Recommended dose of fertilizer (RDF) N:P2O5: K2O (kg ha-1)) N - 86.06 g/ plot P2O5 - 104 g/ plot K2O - 33 g/ plot

Pest management

Endosulfan was sprayed twice to conventionally grown crops and Trichoderma viridi, Pseudomonas fluorescence and neem oil was used in organically grown crops during the period of growth to control pests.

Analysis of different nutrients Fresh crop samples and dry powders of tomato were analysed for nutrient profile (ash, mineral content, Invitro iron availablity, crude fiber, vitamin C and total carotenes (AOAC 1990)). Analysis was carried out in duplicates. Nutrient analysis carried out on fresh weight basis. Shelf life, sensory evaluation of crop samples and microbiological load of the crop were undertaken for tomato of both organically and conventionally grown crops.

Results and Discussions

Ash content of organically grown tomato was found to be significantly higher compared to conventionally grown crops. Vermicompost, farmyard manure, poultry manure application to tomato crop registered significantly higher ash content compared to conventionally grown crop. Among the organic manures tested vermicompost application to tomato crops resulted in significant increase in iron content.

Table 1 : Micromineral Content of Organically and Conventionally grown Tomato Crop Treatment Ash Iron Zinc Calcium Magnesium Kharif Rabi Kharif Rabi Kharif Rabi Kharif Rabi Kharif Rabi VC 0.2 0.22 0.6 0.67 34.4 35.95 53.82 55.5 0.51 0.55 FYM 0.2 0.22 0.54 0.64 34.4 35.95 50.21 51.75 0.35 0.39 PM 0.2 0.22 0.57 0.67 35.01 28.24 58.8 60.33 0.43 0.47 CD 0.2 0.21 0.35 0.45 23.99 25.54 35.84 37.39 0.34 0.38 Control 0.16 0.16 0.3 0.38 23.03 24.58 31.83 33.39 0.27 0.31 F value * * * NS * * * * SEM 0.002 0.003 0.01 0.02 0.14 3.68 0.14 0.1 0.01 0.01 CD(0.01) 0.01 0.01 0.02 0.05 0.15 0.43 0.31 0.17 0.02 C.V% 1.7 2 2 5.7 0.9 0.6 0.4 3 2.9

Similar results were reported by Uma Reddy. (1999) in tomato and onion crops with vermicompost application. Worthington, (2001) reported higher iron content in spinach, tomato, turnip, apple, cabbage, carrots, celery, leek, lentil, lettuce, pepper, potato, apple, pears in organically grown crops, compared to conventionally grown ones. The zinc content of all organically grown vegetables was found to be significantly higher compared to conventionally grown vegetables of both the seasons. Among the various organic manures tested in both the seasons vermicompost application resulted in significantly higher zinc content in tomato crops. Uma reddy (1999) and Anonymous (1993) reported similar increase in zinc content of organically grown vegetables. Among the organic manures tested, application of poultry manure to tomato crops registered significantly higher calcium content in both the seasons. Similar increase in calcium content in organically cultivated vegetables was reported in spinach, cabbage, carrots, beans, tomato, turnip, apple, carrots, celery, leek, lentil, lettuce, pepper, potato, apple, pears by Worthington, (2001). Magnesium content followed different trend in tomato, where poultry manure application registered in significantly higher magnesium content in kharif crop. However a non significant trend was observed with rabi grown tomato among all the treatments applied (Table 1). Increase in magnesium content of organically grown beetroot, spinach, tomato, turnip, cabbage, lettuce, spinach, carrots, apples, pears was reported by Worthington (2001). The absorption of micronutrients such as iron and zinc from the soil was significantly influenced by the application of organic manures i.e., vermicompost, poultry manure, farm yard manure and cow dung. Soil that has been managed organically has more microorganisms, which produce many compounds that influence the plant to absorb more micronutrients from soil. It is also reported that substances such as citrate and lactate combine with the soil minerals and make them more available to plant roots. For iron, in particular, this is especially important because many soils contain adequate iron but in an unavailable form. The presence of these microorganisms explains the trend showing a higher mineral content of organic food crops (Hader 1986, Henis 1986 and Mc Clintock 2004).

Poultry manure application to tomato crops registered significantly higher phosphorus content among all the organic manures applied. Similar higher phosphorus content was reported in organically grown beetroot, spinach, tomato, turnip, cabbage, lettuce, spinach, carrots, apples pears was reported by Worthington (2001). The increase in phosphorus content of organically grown vegetables may be attributed to increased availability of soil phosphorus due to the solubilizing effect of organic acids, which are produced from decomposing organic manures. Further, the organic manures also reduce the fixation of phosphorus and increase the available phosphorus concentration in soil for absorption resulting in increased content of phosphorus in all vegetables. Apart from this, the enzyme activity which may be higher in poultry manure treated plots, might have contributed to increased availability of phosphorus resulting in increased absorption of phosphorus content (Uma Reddy 1999). Among all the treatments tested, conventionally grown tomato registered significantly higher potassium content compared to organically grown vegetables. Similar higher potassium content in conventionally grown crops was reported by Hannaway et al., (1980) Conventional potassium fertilizers dissolve readily in soil water in large quantities while organically managed soils hold moderate quantities in the root zone of the plant and higher potassium fertilizer can reduce the absorption of magnesium and phosphorus content.

Table 2 : Macromineral content (g / 100 g) in organically and conventionally grown Tomato crop Treatment Nitrogen Phosphorus Potassium Kharif Rabi Kharif Rabi Kharif Rabi Vermicompost 203.23 208.28 32.25 33.80 0.28 0.32 Farm yard manure 225.10 226.68 36.56 38.13 0.24 0.31 Poultry manure 255.25 257.05 37.25 38.55 0.26 0.32 Cow dung 206.73 204.78 33.30 34.85 0.23 0.25 Control 261.45 263.00 22.45 24.00 0.30 0.33 SEM 1.03 1.00 0.27 0.29 0.001 0.002 CD(0.01) 3.17* 3.09* 0.84* 0.89* 0.003* 0.005* C.V% 1.00 0.90 1.70 1.70 0.7 1.1 * Significant at P=0.01 level Values with similar superscript are not significant in column NS - Not significant

Conventionally grown tomato registered significantly higher nitrogen content compared to organically treated crops except in kharif amaranthus crop, whereas poultry manure and chemical fertilizer application resulted in similar nitrogen content. Similar results were reported by Uma reddy (1999). Significantly lower nitrogen content was registered with cow dung application in tomato crop (Table 2). Similar results was reported by Uma reddy (1999) in tomato and onion crops. The lower absorption of nitrogen content by the crops from the organic manure i.e., FYM and CD might be attributed to the non availability of adequate nutrients throughout the crop growth period, as the slow released nitrogen from applied manures was reported by Uma Reddy (1999) in onion and tomato with FYM.

Crude fibre content of organically grown tomato crop was found to be significantly higher compared to conventionally cultivated vegetables of both seasons. Vermicompost, poultry manure and cow dung application to tomato registered significantly higher crude fibre content in kharif crop, whereas in rabi, vermicompost application registered significantly higher crude fibre content compared to conventionally grown tomato crop. Similar increase in fibre content was reported in organically grown apples compared to conventional ones (Weibel 1999).

Table 3 : Nutrient content (g/100g) of organically and conventionally grown Tomatoes

Treatment Crude fibre Vitamin C Total carotenes Kharif Rabi Kharif Rabi Kharif Rabi Vermicompost 6.10b 7.35 23.83b 25.90 0.28 0.30 Farm Yard Manure 5.00a 7.15 22.15 23.53 0.21 0.21 Poultry Manure 6.00b 7.25 20.66a 24.14a 0.25 0.25 Cowdung 6.00b 5.95 24.73b 20.89a 0.23 0.22 Control 5.00a 5.75 20.32a 18.83 0.20 0.19 SEM 0.045 0.003 0.43 0.39 0.005 0.007 CD(0.01) 0.18* 0.01 1.69* 1.54* 0.02* 0.03* C.V% 1.10 0.10 2.70 2.40 2.90 4.30 * Significant at P=0.01 level Values with similar superscript are not significant in column NS - Not significant

Vitamin C content of tomatoes was found to be significantly higher compared to conventionally grown vegetables in both the seasons. Similar increase in vitamin C was reported in organically grown vegetables (beetroot spinach, tomato, turnip, cabbage, lettuce, spinach, carrots, apples, pears) compared to conventionally cultivated crops by Salunkhe and Desai (1988); Heaton, (2001); Worthington, (2001); Asami et al., (2003); Venkat Rao, (2004); Lumpkin, (2005) and Uma Reddy et al., (2005). Among all the organic manures tested, vermicompost application to amaranthus, spinach and tomato crops in both the seasons registered significantly higher vitamin C content. Non significant trend was observed with rabi spinach among all the treatments applied.

Vermicompost application to tomato crops resulted in significantly higher total carotenes in rabi season compared to other organically cultivated crops. Cowdung application to kharif tomato crop and vermicompost application to rabi tomato registered significantly higher total carotenes. Significantly lower total carotenes were found in all crops cultivated with chemical fertilizers compared to organically grown vegetables (Table 3).

Quality Characteristics

A non significant trend was observed with total soluble solids (%) (TSS) in tomato crop grown in both kharif and rabi crops. Increase in total soluble solids (%) in onion was reported with vermicompost application compared to chemically fertilized crop reported by Uma Reddy et al., (2005); Prabakharan and Pitchai, (2002); Kumaran et al., (1988) and Lumpkin (2005) also reported increase in total soluble solids in organically grown crops.

Table 4: Quality parameters (g/100g) of organically and conventionally grown tomato crop Treatment TSS Acidity TBARS(%) Kharif Rabi Kharif Rabi Kharif Rabi Vermicompost 11.50 11.75 565.63 571.43 1.02 1.02 Farm Yard Manure 11.25 11.25 433.25 516.66 0.89a 0.89a Poultry Manure 11.25 11.75 531.25 528.57 1.26 1.26 Cowdung 10.75 10.50 522.25 502.38 0.64a 0.64a Control 10.25 10.50 387.50 469.04 0.64a 0.64a SEM 0.342 0.379 21.23 3.62 0.09 0.09 CD(0.01) NS NS 83.32* 14.19* 0.33* 0.33* C.V% 6.20 4.80 6.20 1.00 13.50 13.50 * Significant at PPoultry manure application registered significantly higher acidity in tomato crops of both the seasons compared to chemical fertilized and other organically cultivated tomato. Vermicompost application to tomato crops registered significantly higher total antioxidant activity in both the seasons. Conventionally grown crops contained significantly lower total antioxidant activity in both seasons (Table 4). Similar increase in antioxidant activity in organically cultivated crops was reported by Asami et al., (2003). Organic production methods which are limited in the use of insecticides, herbicides and fungicides compared to conventionally cultivated plants may need to synthesize their own chemical defense mechanisms, and the increase in antioxidant activity has been attributed to this need.

Vermicompost application to tomato crop cultivated in kharif and poultry manure application in rabi registered significantly higher lycopene content compared to other organically grown tomato. Lycopene content of conventionally cultivated tomato was found to be significantly lower compared to all other treatments in both the seasons(Table 5). Similar increase in lycopene in organically grown tomato was reported by Lumpkin (2005).

Table 5: Lycopene content(mg/g) of organically and conventionally grown tomato crop Treatment Tomato Kharif Rabi Vermicompost 6.41a 7.43 Farm Yard Manure 6.20 6.54 Poultry Manure 6.34a 7.77 Cowdung 6.11 5.20a Control 5.88 5.58a SEM 0.03 0.25 CD(0.01) 0.14* 0.97* C.V% 0.80 5.40 * Significant at PShelf life quality Effect of storage temperatures i.e., room temperature and refrigerated temperature on shelf life of organically and conventionally grown tomato crops was studied. Shelf life of organically cultivated tomato crop was found to be significantly higher at both room temperature and refrigerated temperature and in both the seasons compared to conventionally grown crop except kharif tomato stored at refrigerated temperature.

Table 6: Shelf life evaluation (no. of days) of tomato of organically and conventionally grown crops Kharif Rabi Room temp. Refrigerated temp. Room temp. Refrigerated temp. Vermicompost 11 15.50 12.00 16.00 Farm yard manure 10.5 14.50 11.50 15.50 Poultry manure 9 15.00 12.00 16.00 Cow dung 8.5 14.50 10.50 15.00 Control 8 13.00 9.00 14.00 SEM 0.274 0.42 0.27 0.22 CD(0.01) 1.075* NS 1.08* 0.88* C.V% 4.1 4.10 3.50 2.10 * Significant at P=0.01 level NS - Not significant

Among the organically and chemically cultivated tomato crops, vermicompost applied tomato crop, registered significantly higher shelf life when stored at room temperature in kharif season. In rabi season, tomato crop cultivated with vermicompost and poultry manure, when stored at both room temperature and refrigerated temperature registered significantly higher shelf life compared to other organically and conventionally grown crops(Table 6).

Microbiological quality of freshly harvested Tomato crops: Total bacterial count (cfu/g) of freshly harvested tomato of both organically and conventionally grown crops was studied. Cow dung application to tomato crop resulted in significantly higher total bacterial count in kharif crop and poultry manure application to rabi crop registered significantly higher total bacterial count in freshly harvested crop compared to other organically and conventionally grown crops (Table 7). The use of animal manures as fertilizer presents potential microbiological risks if the manure is not properly composted, and can thereby contaminate foodstuffs (Winter and Davis, 2006). E.coli detection rate for non certified organic lettuce produce did not show any generic E.coil (Mukherjee et al., 2004). However, differences in the microbiological safety of non certified and certified organic produce do not demonstrate that certified organic produce is at a higher microbiological risk than conventional produce (Johannessen et al., 2004). Organic animal produce are generally prohibited from using antibiotics and there is an argument that this restriction could theoretically result in increased pathogen levels and elevated neurobiological safety risks (Sato et al.2004).

Table 7:Total bacterial count of freshly harvested tomato of organically and conventionally grown crops Treatment Kharif Rabi Vermicompost 5.25x104 6x104 Farm yard manure 3x104 3.5x104 Poultry manure 5.5x104 7.5x104 Cow dung 6x104 4.75x104 Control 2.5x103 4.5x104 F value * * CV% 9.8 8.1 * Significant at PTable 8 :Sensory evaluation of tomato puree of organically and conventionally grown tomatoes Sensory attributes VC FYM PM CD Control Mean Colour&appearence 3.8abc 3.9c 3.8ab 3.6 3.7ab 3.8 Texture 3.0a 3.3bc 3.0a 3.3bc 3.4c 3.2 Taste 3.6a 3.8 3.5a 4.0 3.6a 3.7 Aroma 3.9a 3.9a 3.6b 3.6b 3.2 3.6 Overall acceptability 3.6a 3.9b 4.0b 4.0b 3.7a 3.8 Mean 3.6 3.8 3.6 3.7 3.5 F value Sem CD (0.01) C.V% For treatment(T) * 0.057 0.080 11.053 For sensory attributes(S) * 0.057 0.080 For (T x S) * 0.127 0.380 * Significant at PColour and appearance attributes of tomato puree prepared with tomato cultivated with farmyard manure and vermicompost registered significantly higher sensory score. Texture attribute of tomato puree prepared with crops cultivated with chemical fertilizer, farm yard manure and cow dung resulted in significantly higher sensory scores compared to puree prepared with other treatments. The taste component of tomato puree prepared with vegetable grown with cow dung registered significantly higher scores compared to puree prepared with other crops. Aroma of tomato puree prepared with crops grown with organic manures (VC & FYM) resulted in significantly higher sensory scores compared to conventional crop. Overall acceptability attribute of tomato puree prepared with crop grown with poultry manure, cow dung and farmyard manure was significantly different from control crop. Mean sensory scores of tomato puree prepared with the crop cultivated using farm yard manure was found to be significantly higher compared to other treatments(Table 8). Toxic parameters Nitrates in organically and conventionally grown crops: Conventionally grown tomatoes were found to contain significantly higher nitrates compared to organically grown crops. Among the organic manures, poultry manure application to tomato of both the seasons resulted in significantly higher nitrates(Table 9). Increase in nitrate levels were reported in conventionally grown crops potatoes, lettuce, leeks, spinach by FineSilver et al., (1989) and Woese et al., (1997).

Table 9: Nitrate content (mg/kg) of organically and conventionally grown tomato crop

Treatment Kharif Rabi Vermicompost 2184.33 2359.44 Farm Yard Manure 2302.07 2426.95 Poultry Manure 2420.28 2483.30 Cowdung 2277.38 2209.91 Control 2649.48 3108.93 SEM 45.20 27.45 CD(0.01) 177.43* 107.76* C.V% 2.70 105.00 * Significant at PConclusion

Organic farming is a reliable way to increase nutrients i.e micronutrients, decrease nitrate levels and also reduce exposure to pesticides through foods. Although many people in the third world do not have enough food even once a day, those in the developed countries are concerned about the quality of food. Increasing attention has been focused on chemical residues of food because of their long-term effects on human as well as environmental health. Alert notices issued by developed nations importing Indian foods with respect to the presence of pesticide residues beyond prescribed levels have already led to serious discussions on the subject of contamination of foods with pesticide residues. Reducing dietary exposure to pesticide residues is an important goal of public and environmental health. Organic farming, seems to offer a low-residue alternative to conventionally grown produce, where exposure to pesticides is minimized and one major reason why consumers are now preferring to buy organic foods. References

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