| With the rapid development of industry, more and more contaminants pollute the environment and heavy metals can remain in the soil and water. Heavy metals can badly damage crops and accumulate in the crops which could harm human beings' health through food cycle. It is the time to alleviate the damage of crops under heavy metals press and decrease the heavy metal accumulations of crops.Photosynthetic Bacteria is a species of bacteria which can progress photosynthesis without releasing oxygen. PSB widely exist in nature such as paddy field, lake, ocean, sludge and soil. PSB has many different functions (nitrogen fixation, dehydrogenation and sulfide oxidation) and play the important role in the cycle of carbon, nitrogen and sulfur. PSB has been successfully used in many fields and has long-range foreground. Environmental pollution and resource crisis are problems that puzzled boffins in many countries. The scientists pay attention to the exploiture of PSB which is a new microbe resource.By using water-culture medium and potted experiment, the effect of Rhodobacter sphaeroides and heavy metals in culture medium in culture progress were researched. The experiments explain the damage of crops under heavy metal press and the function of Rhodobacter sphaeroides in decreasing heavy metal accumulation in crops through growth indexes, heavy metal accumulations and several physiological-biochemical indexes.Part One: Effects of decreasing the Copper Accumulation of wheat and Cole Seedlings by Rhodobacter sphaeroidesBy using water-culture medium, the effects of Rhodobacter sphaeroides solution on the growth and copper accumulation of plants under copper stress such as wheat (Triticum aestivum) and cole (Brassica campestris) , were researched. The results showed that Cu2+ can inhibit the seedling growth. Although the cole seedling and the wheat seedling could accumulate copper, the cole seedling could accumulate more copper by comparison. Rhodobacter sphaeroides improved the inhibition effects on the seedling growth under copper press, the wheat seedlings' above-ground length ,root length, fresh weight were increased 1.2%-54.6%, 2.1%-11.1%, 0.6%-38.4% and the cole seedlings' were increased3.4%-11.3%, 2.6%-16.7%, 7.7%-49.8%, respectively. It could also reduce the copper accumulation of two seedlings on different degree, the copper accumulations of the wheat's leaf and root were decreased 5.5%-62.1% and 6.5%-32.8%, the corresponding copper accumulation of cole seedlings were decreased 32.4%-58.3% and 6.6%-30.0% respectively.Part Two: Effects of Rhodobacter sphaeroides on Plant Growth and Copper Accumulations of Cole Seedlings under Copper Stress in SoilBy using potted experiment, the effects of Rhodobacter sphaeroides solution on the growth and copper accumulation of cole seedlings under copper stress were researched. The results showed that Cu2+ can inhibit the seedling growth. Copper accumulation of the cole seedlings increased with the copper concentrations increasing. The copper accumulations of roots were more than the copper accumulations of leaves. Rhodobacter sphaeroides improved the inhibition effects on the seedling growth under copper press, the cole seedlings' above-ground length ,root length, fresh weight and dry weight were increased 0%-8.8%, 0%- 15.8%, 0.3%-11.4% and 0%-3.7%. It could also reduce the copper accumulation of two seedlings on different degree, the copper accumulations of the cole's whole plant ,leaf and root were decreased 2.8% -11.7%, 1.7% -20.3% and 6.8%-18.8%.Part Three: Effects of Rhodobacter sphaeroides on Plant Growth and Cadmium Accumulations of Wheat and Cole Seedlings under Cadmium Stress By using water-culture medium, the effects of Rhodobacter sphaeroides solution on the growth and cadmium accumulation of plants under cadmium stress, such as wheat and cole were researched. The results showed that cadmium can inhibit the seedling growth. The inhibition effects enhanced with the cadmium concentrations increasing. Low cadmium concentration could advance the growth of plants, when the cadmium concentrations were 0.5mg/L, 10mg/L, 20mg/L and the Rhodobacter sphacroides solution concentrations were 35 mg/L, 70 mg/L, the growth injury of wheat and cole were alleviated and several growth indexes were increased on different degree, the cadmium accumulations of the wheat seedlings' above-ground length ,root length, fresh weight were increased 33.2%-11.3%, 2.5%-6.9%, 11.3%-65.8% and the cole seedlings' were increased 1.0%-14.7%, 5.8%-34.4%, 3.9%-27.6%, respectively. The cadmium accumulation of the plants increased with the cadmium concentrations increasing. The cadmium accumulations of roots were more than the cadmium accumulations of leaves. The Cadmium accumulation of the plants had different levels removal, the wheat's leaf ,root ,whole plant were decreased8.3% -16.4%, 3.8%-31.7%, 3.4% - 15.0% and the corresponding cadmium accumulation of cole seedings were decreased 1.1%-12.3%, 50.6%-58.5% and 0.9%-25.2% , respectively.Part Four: Effects of Rhodobacter sphaeroides on Plant Growth and Cadmium Accumulations of Cole Seedlings under Cadmium Stress in SoilBy using potted experiment, the effects of Rhodobacter sphaeroides solution on the growth and cadmium accumulation of cole seedlings under cadmium stress were researched. The results showed that cadmium can inhibit the seedling growth. The inhibition effects enhanced with the cadmium concentrations increasing, when the cadmium concentrations were 0.5mg/L, 10mg/L, 20mg/L, using the Rhodobacter sphacroides solution, the growth injury of cole were alleviated and several growth indexes were increased on different degree, the cole seedlings' above-ground length ,root length, fresh weight and dry weight were increased 0%-9.7%, 0%-15.8%, 1.1%-11.4% and 0.8%-2.6%. The cadmium accumulation of the cole seedlings increased with the cadmium concentrations increasing. The cadmium accumulations of roots were more than the cadmium accumulations of leaves. Cadmium accumulation of the plants had different levels removal, the cadmium accumulations of the cole's whole plant, leaf and root were decreased 2.8%-26.6%, 1.7%-18.5% and 12.4%-17.3%.Part Five: Effects of Rhodobacter sphaeroides on Cadmium Accumulations and several physiological-biochemical indexes of Wheat Seedlings under Cadmium StressBy using tank farming, the combined effects of Rhodobacter sphaeroides solutions (0%, 15%) and cadmium ion (0, 0.5, 5, 10 and 20mg/L) on the cadmium concentrations in culture solutions,the cadmium accumulations of wheat seedlings and several physiological-biochemical indexes of the wheat seedlings leaves were investigated, during the growth of wheat seedlings. The results showed that the cadmium concentrations in culture solutions decreased with the culture time increasing. Especially, it decreased more visible during the early stage of the wheat growth. With the cadmium concentrations and the culture time increasing, the cadmium accumulations of wheat seedlings increased. From 7th to 10th, the increasing ranges of wheat seedlings' cadmium accumulations were the biggest. Moreover, the cadmium accumulations in roots were more than that in leaves and stems. In the groups that used the Rhodobacter sphaeroides solutions, the cadmium concentrations in culture solutions and the cadmium accumulations of wheat seedlings were lower than the contrast groups. The descending ranges were 1.9%-49.9%, 12.3%-58.1% and 8.3%-53.9% respectively. Under cadmium stress, the contents of malonyldialdehyde (MDA) and proline of the leaves of wheat seedlings increased, but the activities of superoxide dismutase (SOD) and catalase (CAT) of the wheat seedlings leaves decreased with the culture time and the cadmium concentrations increasing. Low concentration cadmium (0.5mg/L) had promotion effect on the compositions of chlorophyll a, chlorophyll b, carotenoid and total chlorophyll in 5 th, but it became inhibition effect in 11th. High concentrations cadmium (>0.5mg/L) had inhibition effects on the compositions of phytochrome, and this inhibition effects strengthen with the culture time and the cadmium concentrations increasing. Through using Rhodobacter sphaeroides solutions, the contents of MDA and proline of the leaves of wheat seedlings decreased, the activities of SOD and CAT increased and the contents of phytochrome also heightened.
|
PDF Full Text Request