| Lotus (Nelumbo nucifera Gaertn) was a specialty aquatic vegetable crop with high economic value, rich nutrition and healthy care function. The planting area and total yield among aquatic vegetables is the first. But in the current production of lotus root, the bad apparent caused of pretty rust and short preservation time largely affects the Lotus products in the domestic market sales. In the cement pits trial, energy dispersive X-ray (EDX) spectrum, scanning electron micrographs (SEM) and ICP techniques were utilized to identify rhizome characterization, the ironplaque formation and chemical composition of Fe, C, O, Al and Si on the rhizome surface of lotus root. The screened four lotus root variety were used to investigate the rhizome charaterization, rhizome biology activity, peroxidase activity, aerenchyma porosity activity and photosynthetic rate of lotus leaves on the rhizome surface, clear and definite the mechanism of iron plaque in lotus root surface. Based on this, this experiment is to study iron reducing bacteria, Phosporus and organic fertilizer, ascorbic acid and citric acid were applied to improve the quality of lotus root and iron plaque formation on the surface of rhizome, investigate effective method of lotus rhizome removal of the iron plaque in the field, which promoted the lotus root planting and promoted our province lotus industry. Specific research results are as follows:(1) Ten lotus cultivars were used to investigate the amounts and chemical composition of iron plaque on the rhizome surface. Iron formed a continuous precipitate on the rhizome surface. Jiantoubaihe had the largest amounts of total Fe on the surface of the lotus rhizomes, follow by Elian No.6 and Wenzhoushangdongou, with Elian No.7 and Jiangsuwuhua having the least total Fe. Most of the total Fe was Fe(III) (64.1%-85.8%), with a small percentage of Fe(Ⅱ) (14.2%-35.9%). Scanning electron micrographs (SEM) demonstrated that the iron plaque was unevenly distributed on the rhizome surface, and had a porous or flocculent structure. Energy dispersive X-ray (EDX) showed that the iron plaque mainly contained Fe, C, O, Al and Si. In addition K, P and Ca were also detected on the rhizome surface of Jiantoubaihe. At the same time, through the study of the iron film with high deposition and low deposition of lotus root varieties found the rhizome activity and porsity of Jiantoubahe and Helian No.6 is much higher than Donghezao’ou, and Jiangsuwuhua, it means their aerenchyma is more developed than Donghezao’ou, and Jiangsuwuhua. Fv/FM has obvious upward trend on the Jiantoubaihe and Elian No.6 leaf, when Photochemical quenching (qp) and non-photochemical quenching (NPQ) and photosynthetic rate were higher than Donghezaoou and Jiangsuwuhua.(2) In order to study the effect of iron reducing bacteria removal of lotus rhizome iron plaque, the experiment is screening of iron-reducing bacteria with the soil and water samples taking from the vegetables experimental base. By screening medium, selected for screening at PTYG, LB, iron-reducing bacteria in a liquid medium, LB medium was more suitable for the growth of iron-reducing bacteria. To study the effects of temperature and carbon source for microbial by setting different conditions of temperature and carbon source than to measure and compare of microbial reduction rate to abtain optimum temperature and optimum carbon source. Final tesults werw LF1 bacteria with the best reduction ability, and the optimum temperature and carbon were 30 ℃ and glucose. The iron-reducing bacteria were removed lotus rhizome field surface iron plaque experiments. In the applied strain 14d after iron reducing bacteria play a role, significantly reduced the total Fe content of lotus rhizome surface, the iron content of the film than the control group decreased 20.9%, that cast iron reducing bacteria can achieve the effect of membrane on the surface of lotus root iron removal.(3) Phosphorus and organic fertilizer were applied to improve the quality of lotus root (Huzhouzaobaihe) and iron plaque formation on the surface of rhizome. The protein and starch content treated by phosphorus fertilizer increased by 145.4% and 61.5% than in control rhizome, sugar and vitamin C content also induced by 48.2% and 112.7%. The iron content on the surface of rhizome was higher in phosphorus fertilizer appication that in control. Organic fertilizer application increased the protein and reducing sugar by 54.0% and 47.2%, while no siginificant effect was showed in starch and vitamin C content, and the iron plaque formation. Co-treatment of phosphorus and organic fertilizer effectively increased protein and vitamin C content. The results showed that application of phosphorus fertilizer effectively improved quality and decreased iron plaque formation.(1) Ascorbic acid and citric acid were applied to improve the quality of lotus root (Donghezaoou) and iron plaque formation on the surface of rhizome. Comparative analysis the effect of rust removal for the lotus root surface and find the best kind of reagent and the amount, and get the feasibility of spreading in the actual production process by field test. The results show that under laboratory conditions, 0.2 mol/L ascorbic acid effectively removed the iron plaque of harvested lotus in short time there than 5% citric acid. Cotreatment of ascorbic acid and citric acid improve the removal efficiency of iron film and reduce the use of reagent. And the application in the field experiment results showed,0.907 kg/ha citric acid and 12.231 kg/ha ascorbic acid of membrane on the surface of lotus root iron removal effect is the best, the percentage of lotus rhizome iron membrane area decreased by 77.8% compared with the control. The results suggested that removal effect is better when the ascorbic acid and citric acid were mixed according to a certain proportion, furthermore, the cost was lower than that ascorbic acid or citric acid was individually used. This method can be applied to the iron plaque removal in lotus root. |
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