Effects Of Foliar Application Of Selenium On Physiological Characteristics And Selenium Enrichment Of Oil Peony ’Fengdan’

Selenium is one of the essential micronutrients for organism.Human body can’t synthesize selenium by itself and can only get it from daily food.In recent years,many researchers have studied selenium and made some progress.Previous studies have shown that exogenous selenium application can effectively achieve the goal of selenium enrichment in edible animals and plants.Peony is a small deciduous perennial woody shrub of Paeoniaceae,which is native to China.Oil peony is a new high-quality woody oil crop in recent years.Peony seed can extract seed oil,which has high nutritional value and is one of its main edible products.At present,the researches on oil peony are mainly focused on genetic breeding,tissue culture,medicinal value,composition analysis and extraction technology of peony seed oil,but there is no report on selenium enrichment of oil peony.In this study,oil peony "Fengdan" was used as the experimental material,and different concentrations of nano selenium were sprayed on the leaves of UAV,respectively: CK(control),S1(100mg / mu),S2(200mg / mu),S3(400mg / mu),S4(550mg / mu).To study the effects of different selenium concentration on the photosynthetic characteristics,physiological and biochemical characteristics and selenium enrichment effect of Fengdan.The results show that:(1)Effect of Selenium Application on Photosynthetic Characteristics of ’Fengdan’The results showed that different treatments significantly increased the photosynthetic rate of’Fengdan’(P < 0.01).The daily change of net photosynthetic rate of ’Fengdan’ under different treatments showed a ’double peak’ pattern,and the high peak appeared at 10:00 and 16:00respectively,showing a significant photosynthetic ’noon break’.However,under CK treatment,the photosynthetic rate of ’Fengdan’ leaves showed a small peak at 10:00,and then the net photosynthetic rate of leaves decreased rapidly.During the period of 12:00-18:00,the photosynthetic rate of ’Fengdan’ leaves was at a low level,and there was no significant peak.At10:00 p.m.,the net photosynthetic rate of ’Fengdan’ leaves reached the peak in a day,which was significantly higher than CK under different treatments,and there was no significant difference between them(P < 0.01);at 16:00 p.m.,there was a second smaller peak in the net photosynthetic rate of leaves under selenium treatment,but there was no significant peak in the net photosynthetic rate of leaves under CK treatment.Under different treatments,the average daily change of net photosynthetic rate of ’Fengdan’ was: S3 > S2 > S1 > S4 > CK.The diurnal variation of intercellular CO2 concentration in Fengdan is generally U-shaped.With the increase of ambient temperature,the intercellular CO2 concentration decreases.During the period of 12:00-16:00,the intercellular CO2 concentration keeps at a low level.With the decrease of ambient temperature,the intercellular CO2 concentration increases slightly.16: At00:00,the CO2 concentration in leaves of S3 and S4 treatments was significantly higher than that of other treatments(P < 0.01).The results showed that there was a significant positive correlation between Se content in seeds and net photosynthetic rate and transpiration rate of leaves(P < 0.05),and the correlation coefficient increased with the increase of spraying concentration.(2)Effects of foliar application of selenium on resistance physiology and osmoregulation of FengdanCompared with the control,the content of soluble sugar,protein and pro in Fengdan were significantly increased(P < 0.01),the activity of superoxide gasifying enzyme(SOD)and peroxidase(POD)were significantly increased(P < 0.05),and the content of malondialdehyde(MDA)was significantly decreased(P < 0.01).There was no significant difference in chlorophyll content,soluble sugar,soluble protein content,superoxide gasifying enzyme(SOD)and malondialdehyde(MDA)among different treatments(P < 0.05);the activity of pod in leaves of S3 treatment was significantly higher than that of other treatments(P < 0.01);the content of proline in leaves of S1 treatment was significantly lower than that of other treatments(P < 0.05),S4 treatment The content of soluble sugar and protein was the highest under the treatment,and the content of malondialdehyde was the lowest under the treatment of S4(P < 0.05).3)Effect of foliar se application on Se enrichment in different organs of FengdanCompared with the control,different treatments significantly increased the selenium content in organs of Fengdan(P < 0.01).With the increase of treatment concentration,the selenium content in organs of Fengdan increased significantly(P < 0.05).The leaf transport coefficient of S1 treatment was significantly higher than that of other treatments(P < 0.01),and the order of leaf absorption coefficient was: S1 > S2 > S3 > S4;the grain transport coefficient increased with the increase of concentration,and the number of grain transport lines of S3 treatment was significantly higher than that of S1 treatment,but the difference was not significant(P < 0.05).The content of selenium in different organs was different,the lowest in roots and the highest in leaves.There was no significant difference between the selenium content in roots and the control(P < 0.05);the selenium content in stems of S1 treatment was significantly lower than that of other treatments(P < 0.05);the selenium content in leaves of S4 treatment was significantly higher than that of S1 and S2 treatment(P < 0.01).Under S1 and S2 treatments,the Se content in different organs of ’Fengdan’ was in the order of leaf > kernel > stem > testa > root,and under S3 and S4 treatments,the Se content in different organs of ’Fengdan’ was in the order of testa > leaf >kernel > stem > root.In conclusion,the photosynthetic characteristics of ’Fengdan’ were the strongest under S3(400mg / mu)treatment,followed by S4(550mg / mu)treatment.Under the treatment of S3(400mg / mu)and S4(550mg / mu),the physiological growth of ’Fengdan’ was more favorable;under the treatment of S4(550mg / mu),the selenium content in organs of ’Fengdan’ was the highest,followed by the treatment of S3(400mg / mu).Therefore,combining the photosynthetic,physiological characteristics and selenium enrichment effect of ’Fengdan’ after applying selenium fertilizer,we can see that under the treatment of S3(400mg / mu)and S4(550mg / mu),the higher photosynthetic and physiological characteristics of ’Fengdan’ can be ensured,and the better selenium enrichment effect can be achieved at the same time.