Study On The Relationship Between Grape Berry Quality And Vascular Structure And Function Mechanism Under Different Gibberellin Treatments

In production,exogenous gibberellic acid(GA3)is normally applied to regulate the fruit growth of grapevine(Vitis vinifera L.),to acquire seedless berries with larger size and higher quality.The vascular bundle in grape berries is the pathway of water and nutrient transport and plays an important role in berry growth and sugar accumulation,so the changes in berry size and berry inner quality are closely related to the structure and function of the vascular tissue of grape berries.In this study,10-year-old ’Shine Muscat’ and ’Summer Black’ was used as the experimental material,and four experimental treatments were set up according to the using methods for GA3 in grapevine production:elongating cluster+seedless+expanding(T1),seedless+expanding(T2),expanding(T3)and water(CK).The effects of several gibberellin treatments on berry quality,vascular tissue structure,and function were studied by paraffin sectioning,dye tracing,and berry cup.The following results were obtained:1.The diameter,weight,and volume of grape berries increased significantly after exogenous gibberellin treatment,which lead to earlier veraison for ’Summer Black’.Moreover,gibberellin treatment increased the soluble solid content of ’Shine Muscat’ and ’Summer Black’,and significantly increased the titrable acid content of‘Summer Black’.In terms of comprehensive characters,T2 of ’Shine Muscat’ had the best effect.T1 and T2 treatment could promote the expansion and growth of ’Summer Black’ and improve berry quality.2.Through statistical analysis of the vascular bundle area under cross-sectional microstructure,it was found that the central vascular bundle area in the equatorial part of the berry is the largest,while the peripheral vascular bundle area in the upper part is the largest.Compared with water treatment,the area of the vascular bundle,xylem,and phloem increased significantly after gibberellin treatment,and the number of vessels in the xylem increased,which was conducive to the differentiation of vascular tissue.The area of the central vascular bundle and the area of the peripheral vascular bundle after the softening stage were the largest under T2.3.By using the dye tracing method to analyze the water transport rate in the ducts,it was found that the water transport capacity of berries showed a pattern of first rapid growth stage>second rapid growth stage>veraison.During the first rapid growth stage,water transport was mainly carried out through the central vascular bundle vessels,while during the second rapid growth stage,water transport was mainly completed through the peripheral vascular bundle phloem;After entering veraison,the water transport rate of berry under gibberellin treatment was significantly higher than that of the control,and the water transport capacity of berry vascular bundle was enhanced.The sugar offloading of berries in veraison and the second rapid growth stage was measured by the berry cup method.It was found that under T2,the sugar offloading amount in the phloem of berries was the highest,significantly higher than that of the control,and its water transport capacity in the vessels was also the best.The above results showed that gibberellin treatment promoted the growth and development of grape berries,was conducive to berry coloring,advanced berry ripening,improved fruit flavor,enhanced berry commerciality,and increased economic benefits.Moreover,gibberellin treatment promoted vascular bundle differentiation increased xylem and phloem area,and enhanced water transport capacity and sugar unloading capacity of berry.T2 had the best effect,which significantly promoted the development of vascular bundle and phloem of berry,enhanced the water transport capacity after veraison,and increased sugar accumulation and sugar unloading in the phloem.