Study On The Effects Of Salt Stress On The Physiological And Biochemical Characteristics Of Seed Germination And Photosynthesis Of Blue Honeysuckle(Lonicera Caerulea L)

Honeysuckle(Lonicera caerulea L)is an excellent economic tree species that consolidates the achievements of poverty alleviation and promotes rural revitalization.It is famous for its high nutritional and healthcare value and is an excellent representative of the third generation of fruit trees.Currently,the area of soil salinization in China is 1.48 billion acres,which poses a huge threat to plant production.Blue honeysuckle itself does not have strict soil requirements,but high concentration of salt stress is also detrimental to growth.In actual production,it is not clear how much salt concentration the seeds and plants of indigo fruit will suffer.This study was conducted in the rain shelter of Northeast Agricultural University from Mid-April to early June 2022.The seeds and potted seedlings of blue honeysuckle were used as test materials,and different concentrations of NaCl were applied to determine the photosynthetic characteristics,growth characteristics,seed germination,etc.of blue honeysuckle under different concentrations of salt stress.The salt tolerance mechanism of blue honeysuckle was explored,to provide theoretical basis and technical support for determining the salinity of the land required for planting blue honeysuckle.The main results are as follows:1.Salt stress inhibited the germination of blue honeysuckle seeds,and the embryo and radicle gradually decreased with the increase of salt concentration.The radicle under 50mmol/L NaCl stress was 14.73%higher than the control,while the embryo was 20.27%lower than the control.Therefore,the salt tolerance of the embryo was greater than that of the embryo.Blue honeysuckle seeds have weak salt tolerance during the germination stage.2.This experiment studied the effects of salt stress on osmoregulation,reactive oxygen species system,and cell membrane system of blue honeysuckle.Salt stress forced a significant increase in the relative electrical conductivity and MDA of blue honeysuckle seeds.SOD gradually increased with the increase in salt concentration,while POD and CAT significantly decreased,with SOD occupying a dominant position in the active oxygen system.Soluble sugar,soluble protein,and proline first increased and then decreased,so blue honeysuckle seeds have a certain self-defense mechanism under low concentration salt stress(50,100 mmol/L NaCl).High concentration salt stress(150,200 mmol/L NaCl)can damage the seed cell structure,and then affect the seed osmoregulation,active oxygen system,and cell membrane system.3.Salt stress inhibits the growth trend of blue honeysuckle,causing its new shoot growth to slow down,leaf area to decrease,and leaves to become narrow and elongated,gradually decreasing with increasing salt concentration.Low concentration salt stress(50 and 100 mmol/L NaCl)has little effect on the growth status of blue honeysuckle.The length of new shoots is 22.22%and 27.55%lower than the control,and the leaf area is 9.52%and 15.63%lower than the control,respectively.The leaf shape status is not significantly different from the control.High concentration salt stress on leaves(150,200 mmol/L NaCl)seriously affects their growth and even causes plant death.The length of new shoots is 45.78%and 45.10%lower than the control,and the leaf area is 28.32%and 40.95%lower than the control,respectively.The leaf shape is narrower than the control.4.Salt stress forced the leaves to curl and turn yellow,resulting in an overall decrease in chlorophyll content and damage to the ultrastructure of chloroplasts.At the first and second weeks,under 50mmol/L NaCl stress,the chlorophyll and carotenoids in the leaves of blue honeysuckle were all higher than those of the control,reaching the lowest value at 200 mmol/L in the fourth week.Pn,Tr,G_S,and Ci gradually decreased with the increase of salt concentration,and reached their lowest values under 200 mmol/L NaCl stress in the fourth week,which were 63.76%,81.08%,85.71%,and 76.14%lower than the control,respectively,with significant differences.From this,it can be seen that stomatal factors limit photosynthesis during stress.