Effects of Iron and Zinc Fertilizers on Antioxidant Activity of PearJujube in Loess Hilly Region

With eight-year-old pear-jujube trees with uniform and good growth as the research object,different concentrations of iron and zinc fertilizers were sprayed to the leaves,and the changes in the contents of vitamin C,total flavonoids,enzyme,as well as the removal rates of hydroxyl radicals,1,1-diphenyl-2-trinitrophenylhydrazine( DPPH) and hydrogen peroxide by polyphenols in pear-jujube were studied,so as to explore the effects of iron and zinc fertilizers on antioxidant activity of pear-jujube in loess hilly region. The results showed that different treatments affected the content of vitamin C and significantly increased the content of total flavonoids in pear-jujube. In the treatment of 0. 6%Fe SO_4+ 0. 3% Zn SO_4( L3),the contents of vitamin C and total flavonoids were both highest,2. 86 mg/g and 3. 02 mg/g,21. 8% and105. 4% higher than CK( P < 0. 05). Different fertilization treatments effectively reduced the activities of ascorbate oxidase and polyphenol oxidase in pear-jujube. The activity of ascorbate oxidase was lowest in the treatment of 0. 6% Fe SO_4+ 0. 3% Zn SO_4( oxidized ascorbic acid0. 069 mg/( g·min) FW,75. 1% lower than CK); and the activity of polyphenol oxidase was lowest in the L3 treatment( oxidized ascorbic acid 0. 146 mg/( g·min) FW,42. 0% lower than CK). Polyphenols of pear-jujube could effectively remove hydroxyl radicals,DPPH· and hydrogen peroxide. This was more significant in L3 treatment,of which the antioxidant activity was the best.

Rules of Changes in Soil Nutrients and Enzyme Activities of Larix principis-rupprechtii in Different Forest Ages

In this study,three different ages of Larix principis-rupprechtii forests in 5,10 and 20 years were selected as the research objects,and the changes in soil nutrient and soil enzyme activities in different growth stages were analyzed. The results showed that the contents of organic matter and available phosphorus in the soil of different growth stages showed a significant downward trend with the increase of soil depth.For different forest ages in the same soil layer,the soil available phosphorus content declined with the increase of the forest age. The organic matter content of 40-60 cm in 20 years of forest age was the lowest in July,which was 4. 17 g/kg,significantly lower than that in other soil layers. Besides,the soil available phosphorus content of 5 years of forest age reached the maximum in July,with an average of 4. 44 mg/kg,which was higher than the available phosphorus content in soil in May and September,but the difference between the three months was not significant. The changes in ammonium nitrogen and nitrate nitrogen content in soil with different forest ages were consistent with the changes in the soil depth,showing a downward trend. In the new leaf stage,the ammonium nitrogen content of the L. principis-rupprechtii forest land in5 years of age at 20-40 and 40-60 cm of the soil depth was 13. 47 and 9. 09 mg/kg,respectively,which was 46. 9% and 64. 2% lower than that at 0-20 cm( 25. 36 mg/kg) of the soil depth. The soil nitrate nitrogen content of 20 years of forest age was 19. 24 mg/kg,which was25. 8% lower than that of 10 years of forest age,showing significant difference( P < 0. 05). In addition,with the increase of the age of L. principis-rupprechtii,soil catalase( CAT),alkaline phosphatase( ALP) and urease( Ure) decreased,and the decline of ALP was slow,while CAT and Ure decreased significantly. In summary,it is concluded that the soil fertility of forest land declined with the increase of forest age on the basis of change trend of soil nutrient and soil enzyme activity in the surveyed forest age.

Importance of Comprehensive Ecological Restoration of Mountains,Rivers,Forests,Farmland,Lakes and Grass:A Case Study of the Shichuan River

With China's economic development and population growth,China's ecological environment continues to deteriorate.The comprehensive ecosystem restoration of the Shichuan River aims to build an ecosystem containing"mountains,rivers,forests,farmland,lakes and grass"by determining scientific and reasonable thickness of foreign soil,pollution restoration,ecological reconstruction,safeguard measures,etc.It brings new vitality to local ecological environment remodeling and economic development.

Research Progress on the Remediation Benefits of Mineral Passivators on Heavy Metal Contaminated Soil

With the continuous development of society,the development of agricultural economy is also accelerating.Meanwhile,a large amount of sludge and waste materials enter the farmland system,and the state of soil heavy metal pollution is becoming more and more serious.In order to ensure food security and the health of people’s lives,a large number of experts and scholars have begun to look for remediation methods for heavy metal contaminated soil.At present,the use of mineral passivators in the remediation technology of heavy metal contaminated soil is a new and healthy recovery method,and has received extensive attention.