Study On Different Leaf Vegetable Resistance Under Pb Stress And The Application Of Special Resistant Vegetables In Natural Pb Polluted Soil

Leaf vegetables planted large area in suburb field, with the advantage of short growth cycle, quick and good economy returns. However, heavy traffic and heavy industrialization polluted the environment, increasing vegetables pollution, threaten human health. And there were a lot of researches showed that Pb limit-exceeding were common in suburb vegetables. Therefore, Screened lower Pb absorbing vegetables, with the theory plants intake heavy metal difference among intra- and inter-specific, planted in suburb polluted field was reasonable for vegetable safe and human health. My study valued vegetables lead contain and tolerance through seed germination and pot culture experiments, as well screened the lower and higher lead absorbing vegetables for hydroponic culture, compared physiological index, found out difference reasons. Finally planted screened vegetables in nature polluted soil in pot and field, to proving their lead absorbed character. The results showed below:1. To study Pb resistance differences of 13 leaf vegetables through seeds germination under Pb stress of 0,50,100,200,400mg/L. The results showed that Pb inhibited seed germination, and depression was much greater as Pb concentration increased. root was the most Pb sensitived index, while seed germination rate influenced the less, which means the root length is the best index to indicate Pb stress of vegetables. The Pb resistance was Brassicaceae Families vegetables much stronger than Amaranthaceae and Compositae. The vegetables, White amaranth (Amaranthus albus), leaf lettuce(Lactuca sativa var. angustata), Italy lettuce(Lactuca sativa var. ramosa Hort.), Huaya sweet-lettuce (Sonchus lingiaus), were much sensitive of Pb stress.2. A pot experiment was carried out to study the plant growth and Pb uptake of 21 kinds of leafy vegetables with the soil contaminated by Pb. The results indicated that Pb decreased biomass of majority vegetables with a few exceptions for the tested vegetables. Pb contents in shoots and roots increased significantly with the increasing of Pb in the soil, and Pb concentrations in roots were much higher than those in shoots. There was significantly difference in Pb content in shoots among three families, which were in the order of Brassicaceae< Compositae< Umbelliferae, but there was no significantly difference in roots between families. The vegetables were divided into four clusters based on Pb content and biomass inhibition. Aijiaoteqing-80-day flowering Chinese cabbage, Bilucutai flowering Chinese cabbage, Zhu mustard and Spinach were found in high biomass and low-Pb concentration, then they should be the low-Pb leafy vegetables and suitable for moderately contaminated soils. High-Pb leafy vegetables included Coriander, Huangxin celery, White amaranth and Liuye water spinach, and Huaya sweet-lettuce was a biomass sensitive type.3. A hydroponic experiment was conducted to investigate the physiological difference of three leaf vegetables (Liuye water spinach, Huaya sweet-lettuce and Bilucutai flowering Chinese cabbage) with different Pb uptake through their biomass, their proline contents, their activities of anti-oxidant enzymes under the condition of Pb stress, and their Pb tolerance analysis by subordinate function. The results showed that lead treatments had insignificant effect on shoot biomass, and lead concentration of vegetables were in the order of Liuye water spinach> Bilucutai flowering Chinese cabbage> Huaya sweet-lettuce. High Pb treatment increased significantly the proline content of Bilucutai flowering Chinese cabbage and Liuye water spinach, while increased insignificantly that of Huaya sweet-lettuce. the SOD of three vegetables increased as the increase of Pb treatments, CAT performed differently from each other, and POD changed little. Subordinate function analysis showed that the tolerance of three vegetables to Pb was in the order of Bilucutai flowering Chinese cabbage> Liuye water spinach> Huaya sweet-lettuce. Thus, the change of proline, SOD and CAT of the three vegetables are based on their tolerance to Pb, and POD was insensitive to Pb stress. Bilucutai flowering Chinese cabbage was metal exclusion type, Liuye water spinach was metal accumulation while Huaya sweet-lettuce was avoidance.4. Pb contain of specific vegetables of different season and different soil indicated that Pb contain may changed under different environment, but the contain orders among vegetables were stable, Pb contain of Zh mustard and Bilucutai flowering Chinese cabbage was much lower than Baijianye amaranth and Liuye water spinach, which means it controled by genes.5. Field culture was carried out in Xie Country Zhucun Town Panyu District on Oct.-Nov. 2009. We planted 6 kinds of vegetables, which included low Pb absorbed vegetables as Zhu mustard, Bilucutai flowering Chinese cabbage, Spinach and Huaya sweet-lettuce and high Pb absorbed vegetables as Liuye water spinach and White amaranth. The results showed that the screened low Pb absorbed vegetables are safe to grow in the light Pb pollution farm.