| Iodine is one of the necessary trace elements to human beings and animals. It has been well known that iodine deficiency can result in a series of physiological disorders and physiological function.If slightly,it can result in goiter but seriously it can result in immune system weakens,and this has become a global sanitation problem. So how to increase the content of iodine in food will be very meaningful. But inorganic iodine can't be well absorbed by bodies and even produces toxieity.Iodine will have wide edible valuation only when it is transformed into biological active organic iodine.In our studies,using biological enrichment,a hydroponic experiment was carried out to investigate the influence of iodine speeies(iodide and iodate), levels on iodine uptake by vegetables as well as on the growth and quality of vegetables and the influence of iodine in preservation procession.So that to provide theoretic basic for studying iodine uptake and accumulation by vegetables and chemical species analysis of iodine invegetables,and ultimately afford effective,safe and scientific approach to the prevention and cure of iodine deficiency disorders(IDD).The main conclusions we reached through our studies are as follows:1.Add different forms (IO3- and I-) and level (0.5,1,2,4,8.mg/L) of exogenous iodine in the culture medium can increase the iodine content of the rape leaf and root. When in a certain content range of iodine (0.5～8 mg/L) in culture medium, the iodine content of the rapeseed leaf and root will be increased with the increasing of the iodine content in culture medium. The iodine content in culture medium nearly 4 mg/L reached saturation, afterwards a downward trend. This shows that indoor cultivation of iodine rape is feasible.2.Add iodine in the culture medium on the growth of rape has significant effect. In a certain level of iodine, rape absorbs appropriate iodine to promote growth and increase yield. But a high concentration of iodine (iodine concentration=1 mg/L) inhibits the growth of rape. When the iodine concentration reaches 8 mg/L, the yield of rape significantly reduces. Therefore, in order to obtain higher yields and get enough iodine, iodine fertilizer should avoid excessive application.3.The rape's tolerance level of the two forms (IO3- and I-) exogenous iodine as:IO3->I-, this shows that I- is more favorable for absorption and utilization of plant than IO3-.4.It is different of vegetable's iodine absorption on the different forms of iodine. The iodine absorption of rape on the two forms of iodine is:I->IO3-. Therefore, it is recommended that choose KI in adding exogenous iodine in cultivation iodine-rich vegetables. 5.Vegetables absorb iodine mainly through root, and transport to the stems and leaves through xylem part. In this process plant organ has active the retention of iodine. In this study the iodine content in the roots is much larger than the stems and leaves (the distribution ratio of the roots and the stems and leaves approximately 2:1). It shows that transportation of iodine from the roots to the stems and leaves is limited.6.It can increase Vc content and decrease nitrate content of rape leaves in the appropriate treatment conditions of iodine ions, on the contrary in the treatment conditions of iodate ions. Therefore the adjunction of appropriate iodine ions, can improve the quality of r iodine-rich rapes.7.When add KI in the culture medium (concentration is 0.5mgI/L), the iodine content of rape roots and stems and leaves reaches the maximum value after 10 days growth. This shows that plants have a certain limit on the iodine enrichment, instead of the whole growth cycle. Therefore, in the process of cultivation iodine-rich vegetables, add appropriate iodine ions within a certain time can achieve the desired results.8.This study shows that the best method is vacuum freezing drying. It is almost no difference between drying the iodine content (60.3933mg/kg) and dry before the iodine content (61.8536 mg/kg). The other drying methods are leading to reduction of iodine content in dehydration rape. Mainly reasons of the reduction of iodine content are high temperature, light and time. Therefore, it is proposed that during processing dehydrated vegetables, using low temperature, rapid methods, such as vacuum freeze drying. It is appropriate for choosing a cool, dry place to preserve dry products. |
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