Identification Of Saline-alkaline Tolerance And Physiological And Biochemical Response Mechanisms Of Different Oat Genotypes

In order to explore the saline-alkaline tolerance of different oat cultivars and screen the cultivars which are suitable for Songnen Plain to grow.This research carried out a study on 49 major oat cultivars from home and abroad with germination and hydroponics experiments and physiological and biochemical response mechanisms of salt-tolerant cultivars Zhangyan 7,Bayou 4,salt-sensitive cultivars Bayou 18,Dingyan 2 with NaHCO₃ stress simulating saline-alkali condition in Songnen Plain.Main results are as followings:By principle component analysis,subordinate function analysis and clustering analysis,comprehensive assessments on 49 major oat cultivars were carried out at germination and seedling stage.Germination potential?GP?,root fresh weight?RFW?,root length?RL?are the three identification indexes for germination stage with underground fresh weight?X4?,aboveground water content?X₇?,underground water content?X8?are the three identification indexes for seedling stage.Zhangyan 7,Bayou 4 are salt-tolerant cultivars,Bayou 18,Dingyan 2are salt-sensitive cultivars.High concentration of NaHCO₃ stress enhanced the relative electrical conductivity but decreased the ?-amylase activity of oat cultivars.The higher the concentration,the greater the variation.All the oat cultivars show severe growth inhibition under 200 mmol·L-1 NaHCO₃ stress.The activity of SOD,POD and CAT of oat cultivars under NaHCO₃ stress firstly increased and then decreased,while MDA content gradually increased.The research shows that salt-tolerant varieties have stronger antioxidant protection system and active oxygen scavenging ability,which can minimize the damage caused by salt-alkali stress to plants,while salt-sensitive varieties have greater degree of membrane peroxidation and greater damage to plasma membrane under adverse conditions.Saline-alkali stress has significant inhibiting to photosynthesis of oats.Low NaHCO₃ concentration can increase the chlorophyll content of oat seedlings,while high concentration can reduce the chlorophyll content.Net photosynthetic rate?Pn?,stomatal conductance?Gs?,transpiration rate?Tr?,chlorophy?fluorescence parameters?Fv/Fm?gradually decreased with the increase of saline-alkali concentration while the intercellular CO₂?Ci?concentration gradually rised.High concentration of NaHCO₃ stress can damage the photosynthetic system of oat seedlings,and the main limiting factors for photosynthesis are non-stomatal factors.At the same saline-alkali concentration,the content of soluble sugar,soluble protein and proline of Zhangyan 7 and Bayou 4 were significantly higher than those of Bayou 18 andDingyan 2.This indicates that salt-tolerant varieties Zhangyan 7 and Bayou 4 can resist osmotic stress by accumulating more osmotic regulating substances,so as to alleviate the damage caused by saline-alkali stress to plants.The Na⁺ content in oat leaves and roots was positively proportional to salt and alkali stress concentration,while K⁺ content was inversely proportional.The Na⁺ content in leaves of all cultivars was significantly lower than that in roots,while K⁺content was significantly higher than that in roots.And at the same stress concentration,Zhangyan 7 and Bayou 4 maintained lower Na⁺content and higher K⁺content than Bayou18 and Dingyan 2.This indicates that salt-tolerant varieties Zhangyan 7 and Bayou 4 have stronger selective ion absorption capacity.The selective absorption and localization of ions are one of the important physiological and biochemical response mechanisms of oat to salt and alkali stress.