Study On Salt-stress Tolerance And Characteristics Of Selenium Accumulation In Cryptotaenia Japonica

Cryptotaenia japonica Hassk (Umbelliferae), a perennial herbaceous plant.It usually favors humid eco-environment. This plant species is both an edibleand pharmaceutical plant. C. japonica is a popular vegetable in Japan andusually served as salad or prepared in soup. Its nutritious and pharmaceuticalnature are of great concerns among agriculturalists and farmers. The aromaticingredient in the whole plant also has commercial and industrial potential. Onlya few studies have been addressed to C. japonica as yet. And these studies havebeen concentrating on the nutrient elements, pharmaceutical research, foodprocessing and reproductive characteristics.The paper made detailed studies on salt-stress tolerance and characteristicof selenium accumulation in C. japonica，which could afford some basicscientific information for the industrialization. The results were as follows:1. The effects of different concentrations of NaCl, NaNO3and CaCl2onthe seed germination of C. japonica were studied. NaCl, NaNO3and CaCl2were applied at concentrations of0,50,150and200mmol/L for salt stresstreatments. The results showed that the germination percentage, relativegermination vigor, germination index as well as the root length of the C.japonica seed all declined in various degrees with the saline salinity increasing.Besides, the relative salt damage rate raised, the germinating time of the seedbegan to postpone and the germination process extended. The fit saltconcentration for C. japonica seed germination was97.78mmol/L NaCl,103.38mmol/L NaNO3, and69.12mmol/L CaCl2, and the half-lethalconcentration and fatal concentration of NaCl, NaNO3and CaCl2were162.04mmol/L and264.87mmol/L,176.05mmol/L and292.33mmol/L,113.76mmol·/L and185.19mmol/L, respectively. Through the linear regression between relative germination percentage of C. japonica seed and salt stress, theinhibition effect was CaCl2had greater effects than NaCl and NaNO3on seedgermination of C. japonica.2. Salt tolerance of C. japonica was researched by measuring the SODactivity, POD activity, CAT activity, the contents of MDA, proline, chlorophyll,soluble protein and soluble suger under treatments of0,50,150and200mmol/L NaCl solutions. The results showed that:(1) Injuries symptom of C.japonica increased and above-ground fresh weight decreased as the NaClconcentration of solution increased.(2)As stress time prolonged, the activitiesof antioxidant enzymes increased under lower NaCl concentration, underhigher NaCl concentration they increased at beginning, and then decreased.(3)MDA content and proline content increased with increase NaClconcentration and time.Chlorophyll content decreased with increase NaClconcentration and time. Soluble protein and soluble suger content increasedunder lower NaCl concentration, under higher NaCl concentration theyincreased at beginning,and then decreased. C. japonica had a certain tolerancewith lower NaCl concentration.3. In the range of application of Se on C. japonica by pot experiment toexamine the effect of Se on growth characteristics, quality and biologicalcharacteristics. The results showed that the highest C. japonica’s growth factors(plant height, leaf area, stem diameter, length of longest root, fresh and dryweight of plant, fresh and dry weight of root, fresh and dry weight of stem,fresh and dry weight of leaf) were observed at0.5mg/kg of Se. Seleniumtreatments significantly increased the total Se content in C. japonica plant. Inthe range of application of Se in this experiment, Se content of C. japonica inroot, steam and leaf was0.15ug/g~64.37ug/g,0.06ug/g~26.45ug/g and0.13ug/g~62.35ug/g. Se content of C. japonica had marked positivecorrelations with soil application of Se. The contents of soluble protein andsoluble sugar of CK were more than other treatments; meanwhile seleniumapplication increased K, Mg, inhibited absorption of Cu and the absorption ofNa, Ca, Zn, Mn and Fe to different extents. Using special concentration of selenium on C. japonica increased MDA, CAT, SOD, POD, chlorophyll andproline to different extents. Comprehensive considering the effects of seleniumapplication on growth, biological characteristics, the selenium content as wellas food safety for human health, the appropriate application rate of Se is0.5mg/kg.