Identification Of Salt Tolerance Of Peanut Varieties At Seedling Stage And Physiological-Biochemical Evaluation

Salinization of land is an important environmental problem in the world.Salt stress in agricultural production has become one of the main factors limiting the productivity of land.Peanut?Arachis hypogaea L.?which has certain saline-alkali resistance belong to medium salt-tolerance crop.The development of peanut production in saline-alkali land plays an important role in improving the productivity of saline-alkali land.In this research,soil and hydroponics culture were used to systematically research on salt tolerance identification and physiological evaluation.The main results are as follows:1.With the increasing of salt concentration,water absorption ratio and rate,seedling emergence ratio and rate,most of the indexes at seedling stage were stressed greatly.0.3%can be used as a suitable salt concentration treatment to identify the salt tolerance of peanut varieties.In addition,it was found that the seed sizes of peanut varieties was significantly correlated with salt tolerance,and the correlation coefficient was 0.614.In non-salt or low-salt environments,the selection of.small size seeds.is conducive to water-saving.In order to ensure emergence and seedlings were robust,in high-salt environment,it is more appropriate to choose.varieties with large size seeds.2.Through comprehensive analysis,the peanut varieties can be divided into five types which were as follows:Highly salt-tolerant type:Fenghua 5,Zhongfeng;Salt-tolerant type:Jihua 2,Shanyou 2,Fenghua 6,Huayu 25,Jihua 13,Yueyou 200,Lu Hua 12;Intermediate type:Luhua 10,Yuyou 16,Haihua 2,Liaohua 5,Lianhua 3,Yuyou 101,Huayu 33;Salt-sensitive:Fuhua 11,Qinglan 2,Zhongkaihua 2,Zhongkaihua 6,Huayu 20,Zhongkaihua 1,Daqinglan,Huayu 23,Jinhua 1012,Haihua 1,Weihua 6,Huayu 32;Highly salt-sensitive type:Huayu 28,Shanyou 27.The predictive equation of testing salt tolerance of peanut varieties was established by stepwise regression,F=2.694 RPH+1.34RPW+2.539 REV-3.353?R²=0.958?.Relative values of seedling emergence rate,plant height and dry weight can be used as the main parameters for identifing salt tolerance.at seedling stage.3.Under 0.1%low salt stress,the net photosynthetic rate of HY25 when accept above600?mol·m^-2·s^-11 light intensity and LH12 when accept above 1000?mol·m^-2·s^-1 light intensity increased respectively.When the salt concentration increased to more than 0.2%,the net photosynthetic rates of LH12 and HY20 when accept above 200?mol·m^-2·s^-11 light intensity decreased significantly,and the net photosynthetic rates of HY25 and HH1 were significantly decreased no matter how strong the light is.The physiological changes of different varieties under different salt concentration were different.Under 0.3%high salt concentration treatment,the relative water content,stomatal conductivity,transpiration rate,SOD and CAT activity and MDA content of salt-tolerant varieties were generally lower than those of salt-sensitive varieties.The increase of proline and soluble sugar content was higher than that of salt sensitive varieties.Under the same salt stress concentration,SPAD value of salt-tolerant varieties decreased lower than that of salt-sensitive varieties.4.Under 150mM high salt stress,compared with HH1 and HY20,the expression of AhNHX1,AhSAMDC and LEA3 genes in HY25 and LH12 was higher,the decrease of AhNHX1 expression was lower,and the increase of AhSAMDC and LEA3 expression was higher.High salt concentration treatment can inhibit the photosynthetic rate of leaves thus affecting the photosynthetic parameters,decrease leaves water content resulted in the decrease of stomatal conductance and transpiration rate,inhibit the anti-oxidation ability and accumulate more MDA made membrane lipid peroxidated,accumulate osmotic substances for resisting to salt environment.but most physiological indexes of salt-tolerant varieties were less inhibited than that of salt-sensitive varieties under salt stress.Salt-tolerant varieties accumulated more osmotic substances than salt-sensitive varieties.At the same time,the expression of salt-tolerant genes of salt-tolerant varieties was higher than that of salt-sensitive varieties.The results can provide reference for selection of peanut varieties and improve.high-yield cultivation techniques a in saline-alkali soil.