Effect Of Different Salinities And Exogenous Thiamin&Pyridoxine On Two Genotypical Maize Seedlings

Maize(Zea mays L.)is one of the valuable food crops in China as well as for whole world.Meanwhile,it has been indicated that salt concentration will be increased all over the world owing to global climate change.Salt is most destructive factor for reproductive and vegetative stages during maize development and growth.Salt is a major factor of limiting maize growth and biomass production on morphological,physiological and biochemical responses and activities.The aim of this study is to evaluate the effects of salt stress plus thiamin and pyridoxine on eco-physiological responses of two maize genotypes,in order to better understandthe morphological,physiological and biochemical mechanisms of salt tolerance.Part I: salty stress1.The fresh shoot biomassesof Jinyu 819 and Jindan 999 significantly declined under the salty treatments(Na Cl,KCl,Na2SO4,K2SO4,Na NO3,and KNO3)as compared to controls,however,the salty stress resulted in a non-significant decreases for the dry shoot and root biomasses of Jinyu 819 and Jindan 999.The treatments of Na NO3 and KCl caused significantly decreases of Fv/fm in Jinyu 819 and Jindan 999.In general,the shoot responses were more sensitive than that of root in genotypes Jinyu 819 and Jindan 999.2.The foliage catalase,peroxidase,and superoxide activities in Jinyu 819 and Jindan 999 enlarged with different rates under the treatments of Na Cl,KCl,Na2SO4,K2SO4.Na NO3 and KNO3.3.Foliage Ca2+ and K+concentrations in Jinyu 819 and Jindan 999 notably decreased under the Na Cl,KCl,Na2SO4,K2SO4,Na NO3 and KNO3 treatments,whereas the all salty treatments caused significant increase of foliage Na+ concentration in Jinyu 819 and Jindan 999.The foliage Cl–,SO42–,NO3–concentrations in Jinyu 819 and Jindan 999 were significantly increased with the corresponding salty stress.Part II: salty stress plus thiamin4.The salty stress(Na Cl,Na2SO4,KCl,and K2SO4)plus thiamin significantly declined the fresh shoot and root biomass,but non-significant decreased for dry shoot and root biomass,indicating the responses of fresh and dry biomass showed a relatively large differencesunder this treatment.5.The foliage enzyme activities of catalase,peroxidase,superoxide,hydrogen peroxide,arginine decarboxylase,diamine oxidase,polyaminoxide,and ethylene as a whole increased with a various extent in Jinyu 819 and Jindan 999 under the salty stress plus thiamin;This treatment tellingly decreased the foliage hydrogen peroxide and superoxide in Jinyu 819 and Jindan 999;The K+ salty stress(KCl and K2SO4)plus thiamin brought about significant decrease of catalase,peroxidase,superoxide,hydrogen peroxide,and diamine oxidase activities.6.The salty application with thiamin significantly reduced the foliage Ca2+ concentration in Jinyu 819 and Jindan 999;The salty application of Na Cl and Na2SO4 plus thiamin significantly lessened K+and enhanced Na+ content in leaves,while the salty application(KCl and K2SO4)with thiamin significantly increased the foliage K+ and reduced foliage Na+in Jinyu 819 and Jindan 999;The foliage Cl–,SO42–,NO3–concentrations in Jinyu 819 and Jindan 999 were significantly increased with the corresponding salty stress(Na Cl,Na2SO4,KCl,and K2SO4)with thiamin.Part III: salty stress plus pyridoxine7.The salty stress(Na Cl,Na2SO4,KCl,and K2SO4)plus pyridoxine only significantly increased the fresh shoot biomass for Jinyu 819 but not for Jindan 999;The treatments increased the dry shoot biomass and decreased the dry root weight in Jinyu 819 and Jindan 999 with different rates.These results indicated that the pyridoxine application can help the growth of maize seedlings to relieve the salty stress.8.The treatments significantly enhanced foliage catalase,superoxide diamutase,hydrogen peroxide,arginine decarboxylase,polyaminoxide,and ethylene activities in Jinyu 819 and Jindan 999;there were non-significant differences between the K+ and Na+salty stress on Jinyu 819 and Jindan 999.9.The significant decrease of foliage Ca2+ concentrationsalso were observed in Jinyu 819 and Jindan 999 under the salty application with pyridoxine;The significant changes of foliage K+ and Na+ contents in Jinyu 819 and Jindan 999 were opposite with the treatments of salty stress and pyridoxine;The Cl–,SO42–,NO3–salty application significantly increased the corresponding foliage Cl–,SO42–,NO3–concentrations in Jinyu 819 and Jindan 999.10.The application of 50 m M Na2SO4 caused significant up-regulations of gene expression Sultr-1,Sultr-1,2,Sultr-2,1,Sultr-3,1,Sultr-3,3,Sultr-3,4,Sultr-3,5,and Sultr-4,1 in Jinyu 819 and Jindan 999.In conclusion,there were no significant differences on salty tolerance for Jinyu 819 and Jindan 999 in response to the thiamin and pyridoxine application,which can reduce the damage of salty stress.Na+ salt was easier to impact on maize biomass of Jinyu 819 while Jindan 999 was much easier to affect by K+ salt.There existed large enzymatic-response differences under the thiamin and pyridoxine application in both Jinyu 819 while Jindan 999.Those results implied that application of Jinyu 819 and Jindan 999 should be paid great attention in saline types,and verify its real effect for maize cultivation.