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According to the World Health Organization, consumption of table salt (being a major carrier of iodine in human diet) should be reduced of 50%. Vegetables biofortified with iodine can become an alternative source of this element for humans. Agronomic recommendations with reference to biofortification have to be developed, including the evaluation of side-effects associated with iodine application to plants. Iodine is not an essential element for plants and hence its effect on crops has not yet been diagnosed. The aim of the study has been to assess the influence of soil fertilization with KI and foliar application of KIO3 on the success of iodine biofortification as well as the mineral composition of lettuce. Lettuce cv. Melodion F1 was cultivated in a field experiment in 2008-2009. Combinations with different soil fertilization and foliar nutrition with iodine were distinguished in the research including: control (without iodine application), three combinations with presowing soil fertilization of iodine (in the form of KI) in doses of 0.5, 1.0 and 2.0 kg I ha–1 as well three combinations with four applications of foliar nutrition with iodine solution (as KIO3) in the concentration of: 0.0005%, 0.005% and 0.05% after using 1000 dm3 of working solution per 1 ha so that the following amounts of iodine were applied: 0.02, 0.2 and 2.0 kg I ha–1, respectively. In lettuce heads, the iodine content as well as the content of: P, K, Mg, Ca, S, Na, B, Cu, Fe, Mn, Zn, Mo, Al, Cd and Pb were determined using the ICP-OES technique, while N-total was assayed by Kjeldahl method. In comparison to the control, only foliar nutrition with 0.05% solution of iodine significantly improved accumulation of this element in lettuce. At the same time, a lower level of nitrogen nutrition was observed in plants from this combination. A significant increase in the N-total content was found only in lettuce plants fed with 2.0 kg I ha–1 dose of KI. In reference to the control, both foliar and soil application of iodine contributed to a higher content of K, Mg, Ca, Mn and Cd as well as a decreased level of P, Cu and Zn in lettuce. Doses, forms and application methods of iodine were found to have produced diverse effects on the content of S, Na, B, Fe, Mo, Al and Pb in lettuce plants.
In order to obtain the optimal technological parameters of lettuce vacuum osmotic dehydration, the effects of osmotic temperature, slice thickness, sucrose concentration, and vacuum degree on the vacuum osmotic dehydration were explored. The lettuce water loss rate and solid gain rate decreased with the increase of slice thickness and vacuum degree, and increased with the increase of sucrose concentration and osmotic temperature. Response surface methodology was applied to analyze the infl uence of the four infl uential factors on the evaluated parameters and the optimization of lettuce vacuum osmotic dehydration was studied. The results indicated that, within the experimental scope, the optimized technological parameters of lettuce vacuum osmotic dehydration are the temperature of 28º C, the slice thickness of 2 mm, sucrose concentration of 47%, the vacuum degree of 22 kPa, and the water loss rate and solid gain rate are 72.16% and 11.82%, respectively.
In the years 2005 and 2006, spring and autumn experiments were carried out with greenhouse lettuce ‘Michalina’ cultivar, which was fertilized with three iron chelates, i.e.: Fe-DTPA, Fe-EDTA+DTPA, Fe-AM-4 in the following doses (mg Fe·dm⁻³): 20 (control), 50, 75, 100 and 125. The objective of the work were the after effect of the mentioned chelates investigated in the autumnal experiments. Containers with peat that were used in spring experiments were stored in the greenhouse until autumn. In mid-September, lettuce seedlings were planted into the stored peat-filled containers after supplementation of the macro- and micro-elements with the exception of iron. No negative action of chelates was found. Plants yielded well without any symptoms of chelate excess which were observed in spring. After the application of the studied chelates, independent of the levels of Fe, the lettuce yields were similar. Increasing Fe levels, independent of chelates, were accompanied by a similar Fe content in leaves, by an increasing content of copper and decreasing contents of manganese and zinc.
Possibilities for using molecular markers to improve genebank efficiency are increasingly present thanks to developments in genebanks and developments in molecular genetics. These possibilities relate to all aspects of genebank management: acquisition, maintenance, characterisation and utilisation. However, two pitfalls should be avoided. The first lies in the neutrality of the most generally used markers, making them less suitable for optimising genetic diversity. The second is related to the considerable costs involved in using molecular markers. In many cases an economical analysis will have to decide if the markers can routinely be used in genebank operations. Some examples of model studies and applications of molecular markers in genebank operations will be presented, in which both genetic and economic aspects will be illustrated briefly. These examples involved existing genebank collections of wild lettuce, cabbage and wild potato.
A differentiated ability of heavy metals accumulation was found between different lettuce cultivars. In combinations with an addition of lead and cadmium grown in autumn, the least amount of lead was accumulated by Agora, Regina and Bona cvs, while the least amount of cadmium was found in Saba and Bona cvs. In spring, Syrena cv. Accumulated the least amount of lead, while Marta cv. showed the least amount of cadmium.
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