| Selenium is one of the essential trace elements in the human body,and selenium deficiency has become a worldwide problem.It is of great practical significance to supplement selenium to the body in a suitable way to prevent and assist in the treatment of selenium deficiency-related diseases,to improve human immunity,and to delay aging.At the same time,the anti-aging effect of selenium has been used in the food industry,and consumers also favor se-rich food.Tomato is one of the fruits and vegetables in the world,which is widely grown,produced,processed and consumed.It is also an important source of dietary antioxidants.Therefore,the study on how to improve the selenium content in tomato fruit and improve tomato quality is particularly important for human health.Meanwhile,it can also provide important theoretical and practical basis for the efficient production of high-quality selenium-rich tomato.In this paper,the effect of selenium accumulation on tomato fruit was studied systematically by spraying different selenium concentration of sodium selenite and biological se solution to tomato,and correlation between activity of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)and selenium content in tomato fruit,which provide scientific basis for production of high quality fresh food selenium-rich tomato adapted to modern life.It consists of the following three parts.Part Ⅰ:The first part:the variety of tomato planted in a greenhouse is Greet.The design of the test was divided into eleven groups,each group with an area of 20m2 and three parallels.The first Group was the control group,which was sprayed with water and fertilizer,and groups numbered 2,3,4,5,and6 were sprayed with selenium,their concentrations are 25 mg/L,50 mg/L,100mg/L,200 mg/L,400 mg/L respectively,groups numbered7,8,9,10,11 were sprayed with biological selenium solution,the concentrations of selenium are25 mg/L,50 mg/L,100 mg/L,200 mg/L,400 mg/L.Color of the first node of the tomato plant began to change as the first day,and the plants were sprayedon the first,seventh,14 th,21th,28 th,and 35 th day respectively,and the tomato fruits were harvested seven days after spraying.On the 14 th day of collecting samples,groups numbered 6 and 11 has severe burning seedlings,the burning rate was 93.33% and 86.67% respectively,groups numbered 5 and 10 has light burning seedlings,and the burning rate was 20% and 3.33%respectively,the other groups are growing well.Compared with the first group,the significant analysis of the burning seedlings rate of each group showed that the difference of burning rate between group NO.6 and NO.11 was extremely significant(P<0.01),and group NO.5 and NO.10 was not significant(P>0.05).Compared with the group NO.5 and NO.10,the difference of the burning rate between group NO.6 and NO.11 was not significant(P>0.05).Therefore,sodium selenite and bioselenium with a concentration of 400 mg/L can not be used for the cultivation of selenium-enriched tomatoes.Part Ⅱ:the content of seleniumin in tomato was measured by hydride flame atomic absorption spectrometry.The results showed that both selenite and bio-selenium could increase the content of selenium in tomato,and the content reached the highest value of group NO.4 and NO.9.The selenium content in the tomato fruit of the experimental group was compared.Compared with the control group,the bioselenium group was significantly different(P<0.05)or extremely significant(P<0.01).There was no significant difference between the group NO.5 and NO.10(P>0.05).The difference between the sodium selenite group and the control group was not significant.The difference between the bioselenium group and the sodium selenite group was compared between the group NO.8,NO.3 and the group NO.9,NO.4,the results were extremely significant(P<0.01),the difference between the group NO.7,NO.2 and the group NO.10,NO.5 was not significant(P>0.05).Spraying the same concentration of different selenium,the content of selenium in tomato increased firstly and then decreased with the increasing of sampling time,the content reached themaximum value at the 28 th days.Therefore,the selenium source with a concentration of 100 mg/L of selenium was sprayed,and the selenium-enriched tomato with the highest selenium content was obtained after harvesting at the 28 th days.Part Ⅲ:Enzyme activity of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)in tomato of the control group(group NO.4 and NO.9)and the selenium concentration of 100 mg/L was mesured Correlation analysis between selenium content and enzyme activity in fruits showed that selenium content was significantly positively correlated with POD and SOD activity values,and low correlation with CAT activity value.Multiple comparisons of enzyme activities were carried out,spraying two selenium sources(P<0.01)increased the activity of SOD and POD significantly.The activity value of bioselenium group was significantly better than that of sodium selenite group.The activity value of CAT showed no significant change.The activities value of SOD,POD and CAT in the fruits of the group NO.4 and NO.9 were reached maximum earlier than those in the first group.Therefore,selenium source with a concentration of 100 mg/L was applied and harvested from the 21 th to 28 th days.The activity of POD and SOD in tomato fruit was the highest.Above all,in the cultivation of selenium-enriched tomato,the concentration of selenium is 100 mg/L and time of harvesting was from the21 th to 28 th days,the content of selenium reached the highest,and the activity of POD and SOD is the best.So,cultivation of tomato can obtain greater economic benefits and provide a scientific and feasible basis for the cultivation of high-quality selenium-enriched tomatoes. |
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