人工脱涩处理对广西野生柿种质果实贮藏性的影响

Effects of artificial deastringency treatment on storability of Diospyros germplasms from Guangxi

关键词:  柿种质, 脱涩处理, 贮藏, 软化, 酶活性

Key words:  Diospyros germplasm, deastringency, storage, softening, enzymatic activity

摘要:

为研究广西野生柿种质资源果实采后软化机制,该研究以广西特有的野生柿种质‘油柿'(YS)、‘农家栽培柿'(ZP)和主栽品种‘恭城月柿'为材料,分析了人工脱涩乙烯利处理的果实采后贮藏中可滴定酸含量、可溶性糖含量、硬度、乙烯生物合成量、色差、可溶性单宁含量、果胶及细胞壁降解酶活性的变化。结果表明:(1)与‘恭城月柿'相比,‘油柿'可滴定酸含量高,可溶性糖含量低,转色缓慢,果实易软化。其中,YS-4最不耐贮藏,乙烯利处理后,贮藏第4天硬度降至1.620 N,第6天可溶性单宁含量下降至2.398 mg·g^-1,整个贮藏期原果胶含量下降最慢,末期可溶性果胶值最低,为0.832%; YS-2最耐贮藏,乙烯利处理第8天硬度为YS-4的3.6倍,贮藏末期硬度在所有‘油柿'中最高。(2)‘农家栽培柿'中乙烯利处理贮藏末期ZP-2可滴定酸含量最高,可溶性糖含量低,转色最缓慢,原果胶降幅最小,可溶性果胶含量最高; 相反ZP-3果实转色快且易软化,可滴定酸含量最低,可溶性糖含量低,原果胶降幅最大,可溶性果胶含量低。(3)‘恭城月柿'PG酶活性和Cx酶活性远远高于‘油柿',各‘油柿'种质的果实软化程度与细胞壁降解酶活性的相关性不同,β-D-Gal酶和Cx酶在‘农家栽培柿'贮藏前期起作用,PG酶在贮藏前期和后期对果实软化起作用,说明不同柿种质品种在软化过程中起主导作用的酶不同。综上认为,与‘恭城月柿'相比,‘油柿'耐贮性差,其中YS-4极不耐贮藏,而‘农家栽培柿'ZP-2极耐贮藏,这为研究柿果实软化机制提供了基础的种质材料。

Abstract:

In order to investigate the softening mechanism of putharvest fruits of Diospyros germplasm, Diospyros oleifera, cultivated persimmon and the main cultivar ‘Gongcheng persimmon' in Guangxi were used as experimental materials to analyze the changes of titratable acid content, soluble sugar content, firmness, ethylene biosynthesis, total chromatism, soluble tannin content, pectin content and cell wall degrading enzyme activities in postharvest storage of artificially dehydrated ethephon. The results were as follows:(1)Compared with ‘Gongcheng persimmon', the Diospyros oleifera had high titratable acid content, low soluble sugar content, slow color change and easy softening of fruits. Among them, YS-4 was the most resistant to storage. After ethephon treatment, the firmness decreased to 1.620 N on the 4th day, and the soluble tannin content decreased to 2.398 mg·g^-1 on the 6th day. The pectin content decreased the most slowly during the whole storage period. The soluble pectin content value was the lowest at the final phase(0.832%); while YS-2 was the most resistant to storage, the firmness of ethephon treatment was 3.6 times than that of YS-4 on the 8th day, and the firmness at the end of storage was the highest among all persimmon germplasms.(2)The titratable acid content of ZP-2 was the highest, the soluble sugar content was low, the change of color was the slowest, the decline of original pectin was the least, and the content of soluble pectin was the highest after the end of storage period of ethephon treatment. On the contrary, ZP-3 fruit color changed quickly and softened easily, the titratable acid content was the lowest, the soluble sugar content was low, the original pectin content was the biggest, and the soluble pectin content was low.(3)Polygalacturonase(PG)and cellulase(Cx)of ‘Gongcheng persimmon' were much higher than D. oleifera during the ripening period after fruit softening. The relationship between the softening degree and the cell wall degradation enzyme activity was different among all the persimmon germplasms. β-D-galactosidase(β-D-Gal)and cellulase(Cx)played an important role in the early stage of storage, while poly galacturonase(PG)played an important role in fruit softening at the early and late stage of storage. The results suggest that different persimmon germplasms have different enzymes that play major roles in fruit softening progress. In general, compared with ‘Gongcheng persimmon', the storage tolerance of D. oleifera, in which YS-4 was extremely intolerant to storage, and ZP-2 was extremely tolerant to storage. These results may provide a basis for the study of fruit softening mechanism of persimmon germplasm materials.