Effects And Mechanism Research Of Iso-osmotic Potential NaCl And PEG Stress On Seed Germination And Seedling Growth Of Lycium Ruthenicum

Salt and Drought are the most important abiotic stress factors affecting plant growth and crop yield,Drought stress and Salt stress have become the main factors restricting plant growth.Seed germination and Seedling growth are the most vulnerable and critical stages in the process of plant life history.They determine the establishment and renewal of plant population,and the distribution and continuation of plant population as well.Lycium ruthenicum is a perennial shrub,in recent years,excessive logging has aggravated the destruction of wild resources of Lycium ruthenicum.The natural distribution area of Lycium ruthenicum has been gradually reduced,degraded seriously,and even died in pieces.In order to further understand the effects of Drought and Salt stress on Seed germination and Seedling growth of Lycium ruthenicum,it is recommended to exploit and utilize this valuable wealth fully and reasonably.This is an important subject in the field of research and development of Lycium ruthenicum.In this paper,the seedlings of Lycium ruthenicum were studied under the same osmotic potential and different gradients of NaCl and PEG-6000 solution to simulate the Salt and Drought stresses of osmotic potential.Analyzed the similarities and differences of Drought stress and Salt stress.Discussed the damage mechanism of drought stress and salt stress on Seed germination and Seedling growth of Lycium ruthenicum,which provided theoretical basis for seed reproduction and cultivation of Lycium ruthenicum.The results show the following:?1?Salt stress and Drought stress had obvious inhibiting effect on Seed germination of Lycium ruthenicum,and low concentration of salt had certain promoting effect on Seed germination.When the osmotic potential was-0.24 MPa,the germination peak of Lycium ruthenicum seeds treated with NaCl was 5th day,which was 1 day earlier than that treated with PEG and Control.When the osmotic potential was-0.74 MPa,the seeds of Lycium ruthenicum stopped germinating under PEG treatment,but still germinated under NaCl treatment,which indicate that Lycium ruthenicum seed germination was sensitive to drought stress and had a certain tolerance to salt stress.?2?Salt stress and Drought stress inhibited the survival and growth measurement of Lycium ruthenicum seedlings.When the osmotic potential was-0.74 MPa,the seedlings of Lycium ruthenicum died under NaCl treatment,but no death occurred under PEG treatment.when the osmotic potential was-1.48 MPa,the survival rates of Lycium ruthenicum seedlings under isotonic NaCl and PEG treatment were only 76.67%and 80%of the control,respectively.Under NaCl treatment was significantly lower than control,indicating that Lycium ruthenicum seedlings were sensitive to salt stress and tolerant to drought stress.?3?Salt stress and Drought stress affected the physiological and biochemical characteristics of leaves of Lycium ruthenicum seedlings.Under isotonic NaCl and PEG treatments,the Relative Conductivity and Malondialdehyde?MDA?content of Lycium ruthenicum leaves increased with the decrease of osmotic potential,and the Relative Conductivity and MDA content,Pro content of leaves under isotonic NaCl treatment were higher than those under PEG treatment.SOD,POD and CAT activity increased first and then decreased with the decrease of osmotic potential.SOD,POD and CAT activity in leaves of Lycium ruthenicum under isotonic NaCl treatment were higher than PEG treatment,which indicated that the damage degree of leaves of Lycium ruthenicum under Salt stress was stronger than Drought stress.?4?Salt stress and Drought stress damaged the ion balance of Lycium ruthenicum leaves.Under isotonic NaCl and PEG treatments,Na⁺ion content in leaves increased with osmotic potential decreasing,K⁺,Ca²⁺ion content decreased,Na⁺/K⁺,Na⁺/Ca²⁺ratio increased,and Na⁺ion content in leaves under isotonic NaCl treatment was significantly higher than that under PEG treatment.It showed that Lycium ruthenicum was not only damaged by osmotic stress,but also mainly accumulated by inorganic ions induced ionic toxicity.