Agronomical And Physiological Traits Responses To Salinity Of Different Oat (Avena Sativa L.) Genotypes

Targeting to select accurate salt stress tolerant phenotype on the bases of their agronomic and physiological responses remains a bottleneck in breeding.This study tends to examine the responses of six Chinese oat（Avena sativa L.）cultivars against four levels of saline stress(1.8,8,16 and 24 dS m^-1).The main objective of this research was to determine the most informative agronomical and physiological traits on genotypic performance in diverse salinity stresses.Stable isotopes compositions of nitrogen(δ¹⁵N)and carbon(δ¹³C)were analyzed in dry matter to quantify the genotypic performances under saline condition.Physiological traits including photosynthetic parameters,glutamine synthetase（GS）&nitrate reductase（NR）enzymes activities,Ion concentrations(Na⁺,K⁺,Ca²⁺,Mg²⁺&P),C and N concentrations were also studied.A clear depiction of significant changes in g_s,δ¹³C_shoot,δ¹³C_root,δ¹⁵N_root,N_shoot,chl,RGR and NR activities were observed between genotypes.Salinity stress applied caused significant decreases in leaf net photosynthetic rate（P_n）,stomatal conductance（g_s）,transpiration rate（T）,intrinsic water use efficiency（WUE_i）,GS,NR,RGR,RWC,carbon concentration in shoot(C_shoot),δ¹⁵N and N concentration both in shoot and roots,whileδ¹³C（shoot and roots）increases as the stress increased.Nevertheless,osmotic stress and ion toxicity effects plant growth by limiting transpiration stream.Similarly,salinity significantly decreases the concentrations of K⁺,Mg²⁺and Ca²⁺,while Na⁺and P concentration increased with rising NaCl concentration in both shoot and root parts.In terms of shoot biomass,25%,40%and 55%reduction were recorded by 8,16 and 24 dSm^-1 salinity levels.Baiyan 7 had the highest shoot biomass across treatments,while Tianyan had the highest SB at 16dS m^-1,as compared to other genotypes.Biomass was positively correlated with gas-exchange traits（P_n&g_s）,enzymes activity（GS&NR）,δ¹⁵N_shoot and N_shoot,while negatively correlated withδ¹³C_shoot and Ion（Na⁺）.The variations observed by oat genotypes under different saline stress levels were associated withδ¹³C,which correlated negatively with biomass across treatments.Our study concludes the involvement of these physiological traits(Lowδ¹³C_shoot,g_s&Na⁺)and(high N_shoot)may provide crucial information regarding genotypic tolerance and their adaptability to salinity.