Impact of mangrove vegetation on seasonal carbon burial and other sediment characteristics in the Vellar-Coleroon estuary, India

This work quantified the total carbon and 12 other sediment characteristics at 10 soil depths, in planted and or natural mangrove forests in comparison with non-vegetated soil for four seasons of the year 2009-2010 in the Vellar-Coleroon estuarine complex, India. The sedi- ment characteristics varied significantly between mangrove-vegetated and non-vegetated habitats or seasons of analysis, but not between soil depths. The mangrove sediments were rich in total carbon and total or- ganic carbon as compared to non-mangrove sediments （p 〈0.01）. Total carbon was 98.2% higher in mature mangroves and 41.8% in planted mangroves than that in non-mangrove soil. Total organic carbon was as much as 2.5 times greater in mature mangroves and 2 times greater in planted mangroves than that in unvegetated soil. Carbon contents also varied many fold by season. Total carbon content was 8.6 times greater during pre-monsoon, 4.1 times greater during post-monsoon and 2.5 times greater during monsoon than during summer （P〈0.01 in all cases）. Similarly, total organic carbon was 5.9 times greater during pre-monsoon, 3.1 times greater during post-monsoon and 69% greater during monsoon than during summer. In general, higher levels of sediment carbon were recorded during pre and post-monsoon seasons than during other seasons. Total carbon concentration was correlated negatively to temperature, sand and phosphorus （P 〈0.01）; positively correlated with redox potential, silt, clay, C/N ratio, potassium （P 〈0.01） and nitrogen （P〈0.05）; but not correlated with soil depth, pH or salinity. This work revealed that the carbon burial was rapid at the annual rate of 2.8% for total carbon, and 6.7% for total organic carbon in mangrove-planted sediment. Cleating of mangroves can result in significantly and rapidly reduced carbon stores.Our study highlights the importance of natural and plantation mangrove stands for conserving sediment carbon in the tropical coastal domain.

Triggering the biocontrol of Botrytis cinerea by Trichoderma harzianum through inhibition of pathogenicity and virulence related proteins

This study reports a strain of Trichoderma harzianum CCTCC-SBW0162 with potential to enhance biocontrol activity against gray mold pathogen, Botrytis cinerea, and with a pivotal role in tomato(Solanum esculentum) plant growth enhancement. A total of 254 Trichoderma isolates were screened by in vitro antagonistic assay. Of these, 10 were selected for greenhouse experiments based on their greater inhibition of B. cinerea.The in vitro antagonistic assay and greenhouse experiments indicated that T. harzianum CCTCC-SBW0162 gave the highest inhibition rate(90.6%) and disease reduction(80.7%). Also, to study the possible mechanism associated with antifungal activity of CCTCC-SBW0162 against B. cinerea, molecular docking was used to assess the interactions between CCTCC-SBW0162-derived metabolites, and pathogencity and virulence related proteins of B. cinerea. The molecular docking results indicated that the combination of harzianopyridone,harzianolide and anthraquinone C derived from CCTCCSBW0162 could synergistically improve antifungal activity against B. cinerea through the inhibition/modification of pathogenicity and virulence related proteins.However, this computerized modeling work emphasized the need for further study in the laboratory to confirm the effect T. harzianum-derived metabolites against the proteins of B. cinerea and their interactions.

Bioaccumulation of trace elements by Avicennia marina

Objective:To analyze the concentrations of 12 micro-nutrients(Al,B,Cd,Co,Cr,Cu,Fe,Mg,Mn,Ni,Pb,and Zn)in different plant parts of Avicennia marina and its rhizosphere soil of the south east coast of India.Methods:The samples were acid digested,then analyzed by using inductively coupled plasma system(ICP-Optical Emission Spectrophotometer).Results:Levels of metals were found in the decreasing order:Cd>Co>Ni>Pb>B>Cr>Zn>Mg>Mn>Cu>Fe>Al.The soil held more levels of metals than plant parts,but within the permissible limits of concentration.Bark and root accumulated higher levels of trace elements in a magnitude of 10-80 folds than other plant parts.The overall bioaccumulation factor in the sampling sites of Vellar,Pichavaram and Cuddalore was 2.88,1.420.47 respectively.Essential elements accumulate high in mature mangroves forest while non-essential elements accumulate high in the industrially polluted mangroves.Conclusions:The ratio between essential and non-essential elements was found higher in young mangrove forest than that in mature mangrove forest and polluted mangrove areas.Thus,the ratio of accumulation can be used as an index of the growth and pollution status of mangroves.