The Salt Resistance Selection Of Capsicum Root Stock And The Research On The Effect Of Grafting To Relieve Salt Stress

Pepper?Capsicum annuum L.?,Solanaceae,and herbaceous plants,are both nutritious and color-enhancing in making food,so their cultivation surfaces are also growing year by year.However,due to the improper cultivation and management of fertilization and other reasons,the soil salinization caused severe damage to the roots of the pepper,so the leaves turn yellow,wilting,and biomass decreased or even died.Therefore,the evaluation and screening of salt-tolerant varieties of pepper and the use of grafting technology are important for improving the salt resistance of pepper and improving the yield and quality of pepper.In this study,four pepper rootstock varieties and four pepper scion varieties were tested with morphological and relative electrical conductivity,and salt-tolerant rootstock varieties‘rh'and salt-tolerant scion varieties‘bj'were selected,and digital image technology was used for correlation analysis on R,G,B values reflecting changes in leaf color and salt damage index;taking‘bj'graft to‘rh',compared with self-rooted seedlings,with 250 mmol/l NaCl treatment,by studying the ion content,relative expression of root NHX1 gene,changes in root ultrastructure,and other indexes of different treatments on different times,to explore the effect of grafting to relieve salt stress.The result is as follows:1.Salt-tolerant rootstock‘rh'and salt-free scion cultivar‘bj'are selected,the half-lethal NaCl concentration of‘bj'was 250mmol/l.2.In 20 days for salt treatment,R value,R/B,G value,G/R and salt damage index have a linear positive correlation at different NaCl concentrations.3.After 250 mmol/l NaCl concentrations,the root activity of‘bj'gradually decreases with time,and MDA content increased gradually;due to the effect of root stock‘rh',the root activity and MDA content of‘jj'changed generally lower than‘bj',indecated that it is processble to graft to pepper to relieve salt stress.4.The Na⁺content,Na⁺/K⁺,and Na⁺/Ca²⁺of‘jj'are generally lower than‘bj',and K⁺content,limited Na⁺ability,and Mg²⁺content of leaf is generally higher than‘bj'.These show that grafting can reduce plant salt damage by regulating ion poisoning and ion balance,thereby increasing plant growth potential.5.The relative expression level of NHX1 gene in‘jj'was lower than‘rh',but higher than‘bj'.Compared with‘bj',the ion regionalization ability on the vacuole membrane of‘jj'was enhanced,then the salt resistance of‘jj'increased.Through the exchange of roots with grafting,NHX1 gene expression was upregulated,leading to the regulation of ion balance was enhanced,which could relieve salt stress.6.The root structure of‘bj'was the most damaged,and‘jj'was relieved because of the change of roots'structural resistance form‘rh'.The strong root structure of‘jj'is able to withstand and alleviate salt damage.7.The overall content of osmotic adjustment substances in‘jj'is higher than‘bj',indicating that stronger ability of osmotic adjustment of‘jj'can relieve salt stress.