Response Of Glycine Soja, Glycine Max And Its Hybrid Descendants To The Chloride (Salt) Stress

The Glycine soja populations {BB52 (the salt tolerant) and N23232 (the saltsensitive)}, the Glycine max cultivars{ Lee68 (the salt tolerant) and N23674,Jackson (the salt sensitive)} and hybrid F4 generation BJ185(BB52×Jackson) wereused as the experimental materials. The seeds and seedlings of those materials weretreated with iso-osmotic (-0.53MPa) PEG-6000, NaCl, Na⁺ -salt, Cl⁺ -salt solutions.The results are as follows:The germination rate of both Glycine max and Glycine soja was declinedsignificantly under NaCl stress. There was no significant difference betweenPEG-6000 and control in the germination rate of Glycine max and Glycine soja, butit can be found that Glycine soja has more flexible adaptation to osmotic stress. Asfor the Na⁺ -salt and Cl^- -salt treatments, the germination rate was declined moresignificantly under Na⁺ -salt treatment. The relative electrolytic leakage and MDAcontents in leaves of Glycine soja were increased obviously in the seedlings ofGlycine max and Glycine soja under NaCl stress, however, the Fv/Fm and ETRvalue of chlorophyll fluorescence were decreased evidently. The changes were notobvious or less under PEG-6000 stress. The change trend of above physiologicalindexes under Na⁺ -salt and Cl^- -salt treatments was basically in line with that underNaCl stress. The changes in Glycine soja were more distinct under Na⁺ -salttreatment than Cl^- -salt treatment, but the changes in Glycine max were more evidentunder Cl^- -salt treatment than Na⁺ -salt treatment.Net photosynthesis rate (Pn) of Glycine max was decreased evidently underNaCl stress. Pn was decreased to a smaller extent under PEG-6000 than under NaClstress. Pn values under Na⁺ -salt and Cl^- -salt treatment were between PEG-6000 andNaCl stress, with the value under Na⁺ -salt treatment being higher than Cl^- -salttreatment. The decline of stomatal conductance (Gs) under NaCl, Na⁺ -salt andCl^- -salt treatment was accompanied by intercellular CO₂ concentration (Ci) increase.However, both the Gs and Ci under PEG-6000 were decreased. No significantdifference in Rubisco activity of Glycine max was found between iso-osmotic PEG-6000 and control. Rubisco activity under NaCl, Na⁺ -salt and Cl^- -salt treatmentwas decreased obviously, of which Rubisco activity under Cl^- -salt were decreased toa larger extent than that under Na⁺ -salt treatment. The accumulative effect of Cl^- andNa⁺ was found under the NaCl treatment. The total contents of Cl^- and Na⁺ inchloroplasts under Cl^- -salt were higher than that under Na⁺ -salt treatment. The totalcontents of Na^- under Cl^- were the highest under NaCl treatment. Theses resultsindicated that the Glycine soja was more sensitive to Na⁺ than to Cl^- and Glycinemax was more sensitive to Cl^- than to Na⁺.Jackson (the salt sensitive, Glycine max), BB52(the salt tolerant, Glycinesoja) and hybrid F4 generations BJ185 (BB52×Jackson) were treated with 50, 100and 200mmol/L NaCl. It was found the changes of relative electrolytic leakage,chlorophyll and MDA contents in F4 generations BJ185 were between its twoparents with the increasing NaCl concentration. Relative electrolytic leakage andMDA contents of BJ185 were declined most obviously under iso-osmotic Na⁺ -salttreatment as BB52. It was more evident that free Put contents were increased inBB52 and BJ185 under Na⁺ -salt treatment than Cl^- -salt treatment, while free Spdcontents were increased more significantly under Cl^- -salt treatment. The value of(Spd+Spm)/Put under Cl^- -salt treatment was higher than that under Na⁺ -salttreatment in BB52 and BJ185. Bound Put contents were enhanced more markedlyunder Cl^- -salt treatment, but there were no diversity in bound Spm and Spd contentsbetween Na⁺ -salt and Cl^- -salt treatment. Theses results indicated that the salttolerance of hybrid F4 generation BJ185 was increased by salt tolerant Glycine sojahybridizing with Glycine max. As for the ionic toxicity under NaCl stress, it was thesame as the BB52 that BJ185 showed more tolerance to Cl^- than to Na⁺. It waspossibly related that higher (Spd+Spm)/Put value was maintained and more boundPAs were accumulated in BB52 and B J185 under Cl^- -salt treatment.