Alleviative Effect of Exogenous SA and PGPB on the Growth Physiology of Antirrhinum majus Under Low Temperature and Weak Light Stress
Antirrhinum majus was used as the test material,normal temperature and light(25 ℃,light intensity 600 μmol·m-2·s-1)as the control,A.majus was treated under low temperature and weak light conditions(5 ℃,light intensity 100 μmol·m-2·s-1).The effects of different concentrations of salicylic acid(SA)and plant growth promoting bacteria(PGPB)on the growth physiology of A.majus seedlings were studied,in order to provide reference for the cultivation of A.majus low temperature and weak light stress.The results showed that under low temperature and weak light stress,the growth of A.majus was inhibited,photosynthesis decreased,and the ASA-GSH cycle was hindered.However,under low temperature and weak light stress,the addition of various concentrations of SA and SA+PGPB had a significant promoting effect on the growth of A.majus,significantly improving its plant height,stem diameter,leaf area,total biomass,and root vitality.Under low temperature and weak light stress,the content of chlorophyll a,chlorophyll b,total chlorophyll(a+b),and carotenoids in A.majus treated with 2 mmol·L-1SA+PGPB increased by 162.1％,128.6％,149.0％,and 102.3％,respectively,compared to the control treatment.The Fv/Fm,Fv/Fo,and ΦPS Ⅱ increased by 136.4％,57.4％,and 200.0％respectively compared to the control,while NPQ decreased by 47.6％.The gas exchange parameters Pn,Tr,and Gs of A.majus increased by 107.7％,237.5％,and 91.8％,respectively,while Ci decreased by 30.4％.Under low temperature and weak light stress,2 mmol·L-1SA+PGPB showed the best effect on the improvement of ASA,GSH,ASA/DHA,and GSH/GSSG in A.majus,while the activities of ascorbate peroxidase(APX),dehydroascorbate reductase(DH AR),monodehydroascorbate reductase(MDHAR),and glutathione reductase(GR)also reached the level under normal temperature and light treatment.The results showed that under low temperature and weak light stress,treatments with SA or SA+PGPB at various concentrations could promote plant growth by increasing chlorophyll content,improving root vitality,improving plant photosynthetic characteristics and chlorophyll fluorescence parameters,enhancing ASA-GSH related antioxidant substances and enzyme activity.Among them,2 mmol·L-1 SA+PGPB had the best effect in alleviating low temperature and weak light stress on A.majus.
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