Effects Of New Anti-cracking Agent On The Pericarp Strength,Fruit Quality And Express Of Caspase-9,EXPA4 In ’Huping’ Jujube

Jujube fruit cracking is an important problem affecting the development of jujube industry.In this study,‘Huping’ jujube,a crackable fruit,was used as materials,to study the effects of new anti-cracking agents on the tensile mechanical properties,the changes of cell wall related substances and enzyme activities,the quality of fruit and the express of Caspase-9 and EXPA4 by spraying different new anti-cracking agents(T1,T2,T3 and T4 were sprayed with new anti-cracking agents I,II,III and IV respectively),to analyze the mechanism of jujube fruit cracking and the effect of new anti-cracking agent on jujube fruit cracking,it provides a reliable theoretical basis for whether the new anti-cracking agent can regulate the factors affecting the cracking characteristics of jujube fruit.The results show:1.The study of tensile mechanical properties of jujube pericarp,it’s results show: With the development of jujube fruit,the tensile strength and elasticity modulus of the peel in the transverse and longitudinal directions gradually increase,the transverse elasticity modulus of jujube peel varies from12.81 to 323.27 MPa,the longitudinal elasticity modulus varies from 12.34 to 350.65 MPa,the results show that the stiffness of mature specimens is much larger than that of young fruit sample,the failure strain gradually decreases,the smallest is on 25 th September,it indicates that the extensibility of the peel fruit sample is stronger than that of the mature sample.T3 and T4 treatment can effectively reduce the elastic modulus of jujube pericarp and increase the fracture strain of jujube pericarp.2.The results of changes in cell wall structure material content of jujube pericarp showed that the content of cellulose and hemicellulose in the pericarp gradually decreased with the development of jujube fruit,the cellulose content decreased significantly by 25.70% from 15 th August to 25 th August,T2 and T3 treatment can effectively increase the cellulose content in jujube pericarp;the hemicellulose content decreased significantly by 42.83% from 25 th August to 5th September,different anti-cracking agent treatment can effectively increase the hemicellulose content in jujube pericarp;the pectin content in jujube pericarp is gradually increasing.With the development of jujube fruit,the cellulase activity in jujube pericarp is gradually increased,different treatments effectively reduced cellulase activity in each period.The PG activity in jujube pericarpl first increased and then decreased,it was the highest on 5th September.The pectinase activity in jujube pericarp increased first and then decreased,pectinase activity was the highest on 5th September,different treatments effectively reduced the activity of Pectinase in different periods.3.The results of RT-PCR analysis showed that: During the development of jujube fruit,the expression levels of caspase-9 and EXPA4 in the pericarp increased first and then decreased,the highest relative expression was found on 25 th August.The relative expression of Caspase-9 gene in T1 and T4 treatments was higher than that in control;the relative expression of EXPA4 gene in T3 and T4 treatments was lower than that in control.4.The contents of soluble sugar,reducing sugar and monosaccharides in different parts of the jujube fruit,namely the vertical upper part(P1),the longitudinal middle part(P2),the longitudinal lower part(P3),the lateral outer part(P4),the horizontal middle part(P5)and the horizontal inner part(P6),were determined,it’s results show: On the longitudinal gradient,on the longitudinal gradient,the soluble sugar content in the control group was the highest in P3 and the lowest in P2,they were 7.38% and 6.11%respectively,and the difference was significant,the soluble sugar content of the four treatments at P1,P2 and P3 was higher than that of the control;on the lateral gradient,the sugar content of P6 was the lowest,and the sugar content of P5 was the highest,they were7.05% and 9.31% respectively,and the difference was significant,the sugar content of the four treatments in the P4 and P6 parts was higher than that in the control,the T3 treatment sugar content in the P5 area increased significantly,and the other treatment contents did not change significantly.On the longitudinal gradient,the content of reducing sugar was the lowest in P1 and the highest in P3,which were 4.49% and 5.10% respectively,but the difference was not significant,there was no significant change in the content of reducing sugars in the four treatments at P1,P2 and P3;on the horizontal gradient,the content of reducing sugars was the lowest in P6,and the content of P5 was the highest,which were 4.71% and 5.19% respectively,the difference of sugar content in different parts was not significant.The content of reducing sugar in the four treatments of P6 was lower than that of the control,but there was no significant change in the content of reducing sugar in the four treatments of P4 and P5.The results of three monosaccharides in jujube fruit showed that: The content of sucrose was the highest in different parts,but there was no significant difference between the content of glucose and fructose.T2 and T4 treatments effectively increased the content of glucose and fructose in different parts of jujube fruit.5.The titratable acid content in the jujube pericarp is higher than that of the flesh in the ripening period,the titratable acid content in the pericarp and pulp of different treatments increased,but the difference was not significant.The content of organic acids in jujube pulp increased with different treatments,and the treatment of T3 and T4 significantly decreased the content of organic acids in jujube pericarp.The Vc content in jujube pulp was significantly higher than that in the pericarp during the ripening period,and the different treatments significantly reduced the Vc content in the pericarp.6.The correlation analysis shows that: The tensile strength of the pericarp was significantly positively correlated with the elastic modulus and negatively correlated with the strain at break.The elastic modulus of the peel was negatively correlated with the cellulose and hemicellulose content.The fracture strain of the peel was positively correlated with the cellulose and hemicellulose content.