Alleviation Effect Of Silicon On Salt Stress Of Peach Seedlings And Evaluation Of Silicon Application Effect In Peach Orchard

As one of the four deciduous fruit trees in China,Peach tree plays an important role in the production of fruit trees.However,the high salt content of some peach producing areas restricts the development of peach industry.Silicon has a role in alleviating plant salt damage,but there were few reports on peach application research.To this end,a 1-year-old seedling[Prunus persica Stoke.]was used as a test material.Salt stress was simulated by 50mmol/L NaCl,and three concentrations of silicon fertilizer(0.3,0.8,1.5mmol/L)were applied on it to study the alleviation effect and physiological mechanism of silicon application on salt damage of peach seedlings.Blank control,salt stress treatment and treatments of applying different concentrations of silicon fertilizer on the basis of salt damage were represented by CK,Na,Si1+Na,Si2+Na,and Si3+Na,respectively.The potted 2-year-old’Rui pan 21/peaches’[Prunus persica(Carr.)Franch.]was used as a test material to study the effect of silicon fertilizer combined with nano-carbon/potassium fulvic acid(CK:no silicon fertilizer control;T1:potassium silicate;T2:diatomaceous earth;T3:potassium silicate+nanocarbon;T4:diatomaceous earth+potassium fulvic acid)on soil physical and chemical properties and peach growth.The main findings were as follows:(1)Compared with the control,salt stress significantly reduced the pigment content,stomatal conductance,intercellular carbon dioxide concentration,net photosynthetic rate and transpiration rate of peach seedlings;Compared with salt stress treatment,the chlorophyll a,chlorophyll b,carotenoid content and net photosynthetic rate of the leaves treated with Si3+Na increased by 45.2%、50.0%、57.1%and 40.9%,respectively,and the difference was significant.Compared with the control,salt stress increased the relative conductivity,soluble sugar and proline content,sodium ion concentration,superoxide anion content,SOD,POD activity and phenolic content of the leaves.Under salt stress,the increase of the above physiological indicators of peach leaves treated with silicon fertilizer was significantly reduced compared with the treatment without silicon fertilizer(except for the content of proline and phenolic substances treated by Si1+Na).However,compared with the control,salt stress increased the sodium ion concentration and superoxide anion content in the roots significantly,while the soluble sugar content,potassium ion content,K~+\Na~+,SOD,POD activity and phenol content were all significantly reduced;Under salt stress,the sodium ion content and superoxide anion content treated with silicon fertilizer decreased significantly compared with no silicon treatment,and the SOD,POD activity and phenol content treated with silicon fertilizer increased significantly compared with the treatment without silicon fertilizer.(2)Under the conditions of simple application of silicon or salt stress,the expression of silicon transporter-encoding genes in leaves showed a trend of decreasing first and then increasing at 0-48h after processing,and then began to increase after 24h and 48h,respectively.Applying silicon fertilizer under salt stress conditions,the expression of the silicon transporter-encoding gene in the leaf was the same as that of the simple application of silicon fertilizer or salt stress,but the expression trend was more moderate and maintained at a relatively stable level.Silicon application under salt stress could significantly increase the silicon content in peach seedlings.(3)In the potted peach test,compared with the control,diatomaceous earth+potassium fulvic acid treatment increased redox potential of soil by 13.6%,increased soil water content by 15.9%,and decreased soil bulk density by 19.4%,the difference was significant;soil urease,catalase,sucrose activity were significantly increased by 41.9%,31.0%,and 80.4%,respectively;The content of alkaline nitrogen and available phosphorus in soil increased by15.9%and 17.2%.The content of available potassium and available silicon in soil under potassium silicate+nanocarbon treatment increased by 25.0%and 18.7%,respectively,and the difference was significant.(4)The application of silicon treatment increased the total nitrogen content of leaves and collaterals of potted peaches,increased the total phosphorus and total potassium content of leaves and roots,and the root silicon content of T3(potassium silicate+nanocarbon)significantly increased by 99.5%;The T3 and T4 treatments increased the net photosynthetic rate and root-shoot ratio by 14.7%,15.1%and 18.5%,23.6%,respectively,with significant differences.