外源赤霉素(GA3)对不同桃品种(系)果实品质的影响

陈 鸿1,2,杜金华1,2,马瑞娟2,张圆圆2,丁 辉2,张斌斌2*,俞明亮2*

1南京农业大学园艺学院,南京 210095;2江苏省农业科学院果树研究所·江苏省高效园艺作物遗传改良重点实验室,南京 210014)

摘 要:【目的】探究外施不同浓度赤霉素(GA3)对不同桃品种(系)果实生长发育及品质的影响,筛选适宜浓度。【方法】以DB2-9、霞晖8号和霞脆桃为试材,分别自盛花后48、50和46 d起,每隔10 d喷施50(T2)、100(T3)和150(T4)mg·L-1的GA3,以喷施等量清水为对照(T1)。在硬核期、膨大期和成熟期比较果实的内外品质及糖酸组分含量。【结果】外施50、100 mg·L-1 GA3显著提高3个品种(系)成熟期果实的单果质量。外施100、150 mg·L-1 GA3显著降低霞脆成熟期果实的果形指数,对DB2-9和霞晖8号成熟期果实的果形指数无显著影响。外施150 mg·L-1 GA3显著提高DB2-9成熟期果实的a*值和a*/b*值,外施100、150 mg·L-1 GA3对霞脆成熟期果实着色的抑制效应较霞晖8号显著。外施100、150 mg·L-1 GA3显著提高霞晖8号成熟期果实的去皮硬度和霞脆成熟期果实的带皮硬度,对DB2-9成熟期果实的硬度无显著影响。对于果实口感而言,外施50~150 mg·L-1 GA3能提高DB2-9成熟期果实的可溶性固形物、总糖含量和糖酸比,外施50、150 mg·L-1 GA3能提高霞晖8号和霞脆成熟期果实的可溶性固形物、总糖和总有机酸含量。【结论】不同桃品种(系)对GA3的反应不同,提高DB2-9、霞晖8号和霞脆成熟期果实品质的外施GA3适宜质量浓度分别为100、50和50 mg·L-1

关键词:桃;GA3;需冷量;果实品质

在中国落叶果树中,桃的栽培面积仅次于苹果、梨,居第3 位[1]。果实品质是决定果品商品价值的关键因素。在生产上,提高果实品质的技术包括套袋、施用外源物质和进行肥水管理等[2-4]。其中,外源植物激素处理是一项重要的提质增效技术[5]

植物激素是一种植物自身生成的信号分子,能够在极低浓度下发挥作用,有无毒、高效且对环境友好的特点,在调控果实发育方面应用广泛。赤霉素是一种酸性二萜类化合物植物生长调节剂,参与种子萌发、茎干伸长、叶片扩展、花和果实发育等过程,其中GA3是一种生产上常用的活性赤霉素。在使用GA3调控果实生长发育方面,前人已在葡萄坐果[6]、苹果果实着色[7]和推迟桃果实成熟[8]等方面开展了研究。相关研究表明,采前叶面喷施GA3可以使桃果实体积增大[9-11],但质量浓度大于100 mg·L-1时,果实质量不再增加[12]。但也有研究发现在硬核期对桃树喷施GA3不能显著影响成熟果实的大小[13]。此外,喷施GA3还会使苹果果实拉长,影响外观品质和贮运特性[14-15]。外施GA3(GA 制剂)会推迟果实成熟,进而推迟或抑制果实成熟色泽的显现[16-18]。Ozkan 等[19]发现采前喷施GA3能够提高樱桃成熟期果实的果肉硬度。外施50、100 和150 mg·L-1 GA3显著提高椰枣果实的可溶性固形物含量[20]。此外,采前外施GA3(GAC)能够提高果实中可滴定酸和可溶性糖含量[21-22]。赵滨涛[23]研究表明,低需冷量桃品种的果实糖酸比显著低于中、高需冷量桃品种,果实总酸含量显著高于中、高需冷量桃品种,这可能与内源激素尤其是GA3的含量有关,还可能与果实所处的生长发育阶段相关[24]。因此,外源GA3可能对需冷量不同的桃果实品质影响有差异。目前,尚未见外源GA3对不同需冷量桃果实品质的影响报道。此外,在全球气候变暖及桃产业南延发展的背景下[25],低需冷量桃的花果管理技术研究也急需加强。多数低需冷量桃成花量高[26],可通过栽培技术手段调控花芽分化,进而减少疏花疏果方面的用工。笔者在本研究中拟以低、中、高需冷量桃为研究对象,探讨外源GA3对果实品质的影响,进而筛选适宜的外源GA3浓度。

1 材料和方法

1.1 材料与处理

试验于2023 年在江苏省农业科学院桃试验园进行。试验材料为DB2-9品系、霞晖8号和霞脆,各品种(系)桃物候期和需冷量如表1所示。树形为两主枝“Y”形,株行距2 m×5 m,南北行向,起垄栽培,生草覆盖,按常规方式进行田间土肥水管理和病虫害防治。

表1 不同桃品种(系)需冷量与物候期
Table 1 Chilling requirement and phenological period of different peach varieties(strains)

注:表中所示的日期为相应物候期的样品采集日期。
Note:The date shown in the table is the sample collection date of the corresponding phenological period.

品种(系)Variety(strain)需冷量Chilling requirement/h DB2-9霞晖8号Xiahui 8霞脆Xiacui取样时间(年-月-日)Sampling time(year-month-date)盛花期Blooming stage 2023-03-04 2023-03-11 2023-03-15成熟期Ripening stage 2023-06-12 2023-07-29 2023-07-05 200 546 606硬核期Hard core stage 2023-05-10 2023-06-03 2023-06-03膨大期Expansion stage 2023-05-18 2023-07-16 2023-06-20

根据预试验结果和物候期观测数据,在盛花后48、50 和46 d 分别对DB2-9、霞晖8 号和霞脆喷施GA3,喷施质量浓度均设为50(T2)、100(T3)、150(T4)mg·L-1,以喷施等量清水作为对照(T1)。喷施时以叶面滴液为度,每隔10 d 喷施1 次,共4次。每处理3株树,生长势一致,单株小区。

在每个品种(系)的果实硬核期、膨大期和成熟期采集果实样品,用于品质指标测定。样品采集时,每处理每树按东、西、南、北4个方位随机采取树体中上部无病虫害、无机械损伤的果实各10 个,迅速带回实验室,每处理随机选取20 个果实,用于相关指标的分析测定,3次生物学重复。测定完大小、单果质量、色差、硬度和可溶性固形物含量的果实用削皮器去皮,削取果肉,剁碎混匀,液氮速冻,置于-80 ℃冰箱保存,用于测定可溶性糖和有机酸含量。

1.2 指标测定

1.2.1 果实大小测定 用精确度为0.01 mm的电子数显卡尺(桂林广陆数字测控股份有限公司)测定果实纵径、横径,纵径和横径的比值即为果形指数。

1.2.2 单果质量测定 用分度值为0.1 g 的JA5003型电子天平(中国舜宇恒平公司)测定单果质量,以g表示。

1.2.3 色差测定 用ColorQuest XE 色差计(HunterLab,美国),采用Hunter Lab表色系统测定果实赤道部位4 个点的外果皮亮度值(L*)、红色饱和度(a*)及黄色饱和度(b*),并计算色饱和度(C),C=(a*2+b*21/2

1.2.4 硬度测定 用TA.XT Plus质构仪(Stable Micro Systems,英国)测定果实缝合线两侧腹部的带皮硬度和去皮硬度,因不同生长发育期果实的硬度不同,硬核期和膨大期果实使用的探头直径为2 mm,成熟期果实使用的探头直径为8 mm,以利于探头贯入果实,测试深度5 mm,贯入速度1 mm·s-1[27],以N为单位。

1.2.5 可溶性固形物含量(SSC)测定 果实SSC用手持式便携数显折光仪PAL-1(ATAGO,Itabashiku,东京,日本)测定。测定位置为果实两侧腹部中果皮[27],以%为单位。

1.2.6 可溶性糖和有机酸含量测定 用高效液相色谱(Agilent 1260 infinity ii)测定果肉的蔗糖、葡萄糖、果糖、山梨醇、苹果酸、柠檬酸和奎尼酸含量,所用标准品均为色谱纯,购自Sigma公司。

可溶性糖含量的测定使用Transgenomic 的CARBOSep CHO-620 CA 柱(10 μm 粒径,6 mm×250 mm),流动相为ddH2O,双侧柱温80 ℃,使用VWD 检测器。有机酸含量的测定使用Agilent 的ZORBAX SB-Aq 柱(4.6 mm×250 mm ID,5 µm),RID 检测器,λ=214 nm。以上进样均3 次重复[28]。总糖含量=蔗糖含量+葡萄糖含量+果糖含量+山梨醇含量,总有机酸含量=苹果酸含量+柠檬酸含量+奎尼酸含量,以mg·g-1为单位。以总糖含量和总有机酸含量的比值计算糖酸比。

1.3 数据处理与分析

采用SPSS 22.0(SPSS Inc.,美国)进行方差分析。以LSD法分析不同处理间的差异显著性,采用Excel软件制图。

2 结果与分析

2.1 果实外在品质

2.1.1 果实质量 如图1 所示,不同质量浓度GA3处理的3个桃品种(系)的单果质量在硬核期已表现出差异,从硬核期至成熟期,各品种(系)果实的生长速率均存在差异。对于成熟期果实的单果质量,DB2-9 以T2、T3 处于较高水平且二者差异不显著,但显著高于T1、T4(图1-A);霞晖8 号和霞脆各处理果实的单果质量排序为T2>T3>T4>T1(p<0.05)(图1-B、C)。可见,不同质量浓度的GA3处理对不同品种(系)桃的单果质量有较大影响,外施50、100 mg·L-1 GA3可起到增大果个的作用,质量浓度过高则会延缓果实膨大速率。

图1 不同质量浓度外源GA3对不同需冷量桃单果质量的影响
Fig.1 Effects of different concentrations of exogenous GA3 on single fruit mass of peaches with different chilling requirements

2.1.2 果形指数 从图2 可知,外施不同质量浓度GA3对3个品种(系)膨大期果实的果形指数影响存在较大差异,而对DB2-9 和霞脆硬核期果实的果形指数无显著影响。对于成熟期果实的果形指数,DB2-9 处理间差异不显著(图2-A);霞晖8 号以T2处于最低水平(p<0.05),而其他处理差异不显著(图2-B);霞脆各处理排序为T1、T2>T3>T4(p<0.05)(图2-C)。可见,不同质量浓度GA3对不同品种(系)桃的果实形状影响不一,50 mg·L-1 GA3可显著降低霞晖8号成熟期的果形指数;100、150 mg·L-1 GA3可显著降低霞脆成熟期的果形指数。

图2 不同质量浓度外源GA3对不同需冷量桃果形指数的影响
Fig.2 Effects of different concentrations of exogenous GA3 on fruit shape index of peaches with different chilling requirements

2.1.3 果实着色 图3 表明,不同质量浓度GA3对霞晖8 号和霞脆硬核期果实L*值无显著影响,对3个品种(系)膨大期L*值的影响不一。对于成熟期果实的L*值,DB2-9各处理间差异不显著(图3-A),霞晖8 号以T2 显著高于其他处理(图3-B),霞脆各处理排序为T1>T2>T4>T3(p<0.05)(图3-C)。

图3 不同质量浓度外源GA3对不同需冷量桃果皮色差的影响
Fig.3 Effects of different concentrations of exogenous GA3 on peel colour difference of peaches with different chilling requirements

不同质量浓度GA3对3个品种(系)的硬核期和膨大期果实a*值的影响有差异。对于硬核期果实的a*值,DB2-9和霞脆T3>T1(图3-D、F);霞晖8号T4 显著低于其他处理(p<0.05)(图3-E)。对于成熟期果实的a*值,DB2-9 各处理排序为T4>T1>T3、T2(p<0.05),霞晖8号各处理间无显著差异,霞脆各处理排序为T1>T2>T4>T3(p<0.05)。

DB2-9各处理在膨大期和霞晖8号各处理在硬核期果实C 值的差异不显著(图3-G、H);对于硬核期果实的C 值,DB2-9 的T4 显著低于其他处理;在膨大期,霞晖8号和霞脆T1显著高于其他处理(p<0.05)(图3-H、I)。对于成熟期果实的C 值,DB2-9和霞脆为T3、T4<T1(p<0.05),而霞晖8 号各处理间差异不显著。

外施不同质量浓度GA3对3个品种(系)果实a*/b*值的影响存在差异。在硬核期和膨大期,DB2-9 的T3、T4显著高于T1(图3-J);而对霞晖8号的影响相反(图3-K);霞脆T2 显著高于T1(p<0.05)(图3-L)。对于成熟期果实的a*/b*值,DB2-9 和霞晖8 号各处理排序为T4、T3>T1>T2(p<0.05);霞脆各处理间差异不显著。

总体上看,与对照(T1)相比,外施150 mg·L-1 GA3有利于DB2-9 成熟期果实着色,不同质量浓度GA3对霞晖8 号成熟期果实的色泽影响较小,高质量浓度GA3不利于霞脆成熟期果实着色。

2.2 果实内在品质

2.2.1 硬度 由图4 可知,不同质量浓度GA3处理的3个桃品种(系)的带皮硬度在硬核期已表现出差异,从硬核期至成熟期,各品种(系)果实的硬度降低速率也不相同。对于成熟期果实的带皮硬度,DB2-9各处理间无显著差异(图4-A);霞晖8号各处理排序为T4、T1>T2、T3(p<0.05)(图4-C);霞脆为T3、T4>T2、T1(p<0.05)(图4-E)。

图4 不同质量浓度外源GA3对不同需冷量桃果实硬度的影响
Fig.4 Effect of different concentrations of exogenous GA3 on fruit firmness of peaches with different chilling requirements

外施GA3对霞晖8号和霞脆硬核期和成熟期果实的去皮硬度影响较大。对于3个品种(系)成熟期果实的去皮硬度,DB2-9各处理间无显著差异(图4-B);霞晖8 号各处理排序为T4>T3>T1、T2(p<0.05)(图4-D);霞脆T2>T1(p<0.05),T3、T4 处理的去皮硬度略低于T2,差异不显著(图4-F)。可见,不同质量浓度GA3对不同品种(系)桃的果实硬度影响不一,与对照(T1)相比,100 和150 mg·L-1 GA3处理可提高霞晖8号成熟期的去皮硬度和霞脆成熟期的果实硬度;3 种质量浓度的GA3对DB2-9 成熟期的果实硬度无显著影响。

2.2.2 可溶性固形物含量 如图5所示,不同质量浓度外源GA3能提高DB2-9在3个时期果实的可溶性固形物含量(SSC),霞晖8 号和霞脆各处理下果实SSC的变化趋势均存在差异。对于3个品种(系)成熟期果实的SSC,DB2-9各处理排序为T4、T3>T2>T1(p<0.05)(图5-A);霞晖8 号为T2>T4>T3>T1(p<0.05)(图5-B);霞脆T4处理显著高于其他处理(图5-C)。由此可知,与对照(T1)相比,150 mg·L-1 GA3均能显著提高3个品种(系)成熟期果实的SSC。

图5 不同质量浓度外源GA3对不同需冷量桃果实可溶性固形物含量的影响
Fig.5 Effects of different concentrations of exogenous GA3 on soluble solids content of peach fruits with different chilling requirements

2.3 糖酸组分含量

2.3.1 可溶性糖含量 图6表明,不同质量浓度GA3对3个桃品种(系)果实的蔗糖含量影响明显,在3个时期内,各品种(系)不同处理间的变化趋势不尽相同。对于成熟期果实的蔗糖含量,DB2-9各处理排序为T3、T4>T2>T1(p<0.05)(图6-A);霞晖8 号T2处理显著高于其他处理(p<0.05)(图6-B);霞脆T3处理显著低于T1、T2和T4(p<0.05)(图6-C)。

图6 不同质量浓度外源GA3对不同需冷量桃果实可溶性糖含量的影响
Fig.6 Effects of different concentrations of exogenous GA3 on soluble sugar content of peach fruits with different chilling requirements

从硬核期至成熟期,不同质量浓度GA3处理的3个品种(系)果实的葡萄糖含量变化趋势有所不同。对于硬核期和膨大期果实的葡萄糖含量,DB2-9的3种质量浓度GA3处理组均高于T1(图6-D);而霞脆与之相反(图6-F)。对于成熟期果实的葡萄糖含量,DB2-9 各处理组排序为T3>T4、T2>T1(p<0.05);霞晖8号和霞脆各处理间差异不显著(图6-E、F)。

不同质量浓度GA3处理的3个品种(系)果实的果糖含量变化趋势差异较大,对硬核期和膨大期果实的果糖含量影响显著。对于成熟期果实的果糖含量,DB2-9 各处理排序为T4、T3>T2>T1(p<0.05)(图6-G);霞晖8 号和霞脆各处理间差异不显著(图6-H、I)。

不同质量浓度外施GA3显著降低了3 个品种(系)硬核期果实的山梨醇含量,对各品种(系)膨大期果实的山梨醇含量也有较显著的影响。对于成熟期果实的山梨醇含量,3个品种(系)的3种质量浓度GA3处理组均显著高于T1(p<0.05)(图6-J、K、L)。

不同质量浓度外源GA3对3个品种(系)硬核期和膨大期果实总糖含量的影响不一。对于成熟期果实的总糖含量,DB2-9 各处理排序为T3、T4>T2>T1(p<0.05)(图6-M);霞晖8 号为T2、T3>T4、T1(p<0.05)(图6-N);霞脆各处理间差异不显著(图6-O)。

综上所述,50、100 mg·L-1 GA3 能显著提高DB2-9和霞晖8号成熟期果实的可溶性糖含量,3种质量浓度的GA3对霞脆成熟期果实可溶性总糖含量的影响不显著。

2.3.2 有机酸含量 通过对3个品种(系)果实有机酸含量变化的分析,发现不同质量浓度GA3处理的3个品种(系)果实的奎尼酸含量降低速率存在差异(图7)。对于成熟期果实的奎尼酸含量,DB2-9 各处理排序为T3、T4>T2>T1(p<0.05)(图7-A);霞晖8 号T4 处理显著高于其他处理(图7-B);霞脆T3处理显著高于其他处理(图7-C)。

图7 不同质量浓度外源GA3对不同需冷量桃果实有机酸含量的影响
Fig.7 Effects of different concentrations of exogenous GA3 on organic acid content in peach fruits with different chilling requirements

外施不同质量浓度GA3对3个品种(系)硬核期果实苹果酸含量的影响存在显著差异。膨大期各品种(系)T4 处理的苹果酸含量均最高(p<0.05)。对于成熟期果实的苹果酸含量,DB2-9 各处理间差异不显著(图7-D);霞晖8 号和霞脆的T1 处理均显著低于其他处理(p<0.05)(图7-E、F)。

从硬核期至成熟期,不同质量浓度GA3处理的3 个品种(系)果实柠檬酸含量变化趋势存在差异。对于成熟期果实的柠檬酸含量,DB2-9 各处理排序为T4>T2>T1>T3(p<0.05)(图7-G);霞晖8号为T3、T1>T4、T2(p<0.05)(图7-H);霞脆为T2>T1>T3>T4(p<0.05)(图7-I)。

从硬核期到成熟期,不同质量浓度GA3处理的3 个品种(系)果实总有机酸含量降低速率有所差异。对于成熟期果实的总有机酸含量,DB2-9 各处理排序为T4>T3、T2>T1(p<0.05)(图7-J);霞晖8 号为T4、T3>T2、T1(p<0.05)(图7-K);霞脆为T3>T2>T4>T1(p<0.05)(图7-L)。可见,外源喷施50~150 mg·L-1 GA3可提高3 个桃品种(系)成熟期果实中的有机酸含量。

2.3.3 糖酸比 如图8所示,不同质量浓度GA3处理的3个品种(系)从硬核期至成熟期果实糖酸比增长速率不尽相同。对于成熟期果实的糖酸比,DB2-9的T3处理显著高于其他处理(图8-A);霞晖8号各处理间差异不显著(图8-B);霞脆各处理排序为T4、T1>T2>T3(p<0.05)(图8-C)。外施50~150 mg·L-1 GA3可提高DB2-9 膨大期和成熟期果实的糖酸比,而外施50和100 mg·L-1 GA3可降低霞晖8号和霞脆硬核期和膨大期果实的糖酸比。

图8 不同质量浓度外源GA3对不同需冷量桃果实糖酸比的影响
Fig.8 Effects of different concentrations of exogenous GA3 on sugar-acid ratio of peach fruits with different chilling requirements

3 讨 论

3.1 不同品种(系)桃果实外观品质受外源GA3调控

在桃生产过程中,提高果实综合品质是一个关键环节。而外源赤霉素在调控果实发育和提高果实品质方面有着重要作用[29]。前人研究发现外源赤霉素对果实大小、形状、单果质量、色泽、硬度和糖酸含量等方面均有影响[30-32]。GA3能够提高与细胞壁松弛的相关酶活性[33],并提高参与细胞伸长生长相关基因的转录水平[34],从而使得果实增大并拉长。赤霉素可以通过激活糖代谢相关酶而调控源库关系及库容量,从而提高果实质量[35-37]。外施50 mg·L-1 GA3使兔眼蓝莓成熟果实纵径和横径显著增加,且提高了果实的果形指数[38]。Li 等[39]研究表明,外施1.25 mmol·L-1 GA4+7能够提高桃的单果质量。笔者在本研究中发现,外施GA3对霞晖8 号和霞脆3 个时期单果质量的影响与Li等[39]研究结果一致,但外施100、150 mg·L-1 GA3会降低DB2-9在硬核期和膨大期果实的单果质量。外施GA3会抑制桃花芽分化[40],且低需冷量桃品种花芽开始分化的时间较中、高需冷量桃品种早[41]。本研究中有关外源GA3对不同需冷量桃成花的影响与前人研究结果一致。因此,推测外源GA3影响了DB2-9 早期花芽的发育,导致植物营养分配紊乱,同化物从叶片向果实的运输受阻,影响了低需冷量桃果实的前期发育。此外,外源GA3能显著提高DB2-9 在膨大期果实的果形指数,这与前人的研究结果一致[34],而外施50 mg·L-1 GA3处理的霞晖8号3个时期和不同质量浓度外源GA3处理的霞脆成熟期果实的果形指数与前人[34]的研究结果不一致。不同蓝莓品种果实的形状差异与果实在发育过程前期的平周分裂和中后期的垂周分裂有关,垂周分裂持续的时间越长则果形指数越大[42]。DB2-9果实由硬核期发育至膨大期的时间较短,推测外源GA3通过促进DB2-9 果实细胞的垂周分裂而提高果形指数。霞晖8号和霞脆果实发育过程中硬核期更长,推测外源GA3能够促进霞晖8号和霞脆果实细胞的平周分裂而降低果形指数。

施加外源GA3会抑制果实类胡萝卜素的合成,不利于果实的着色[43]。张颖[44]研究表明外施GA3不利于成熟期桃果实红色的显现,且外施浓度越高,a*值和b*值越小。还有研究表明,喷施赤霉素不能显著改变桃成熟期果实的色泽[45]。笔者在本研究中的结果表明,外源GA3对霞脆桃成熟期果实着色也具有抑制效应,且这种作用随需冷量的升高而增强。在樱桃转色期(35 DAFB)外施GA3会延迟中熟品种成熟色泽的显现,而降低了早熟品种成熟果实的IAD;外源GA3抑制了早熟樱桃品种UFGTs基因的转录上调,而促进了中熟品种ANR 基因的表达[46]。推测外源GA3对不同需冷量桃品种(系)也存在相似的影响。糖是花青素苷合成的底物,并作为花青素苷合成的能量来源[47]。不同浓度外源GA3能提高DB2-9和霞晖8号成熟期果实的总糖含量。推测外源GA3促进低、中需冷量桃成熟期果实的可溶性糖积累,因此减弱了外源GA3对成熟期果实着色的抑制作用。

3.2 不同品种(系)桃果实内在品质对外源GA3施用反应的敏感性不同

前人有关外源GA3对果实发育和品质的影响研究多集中在成熟期,而缺乏对果实生长发育期的研究。研究发现,外源GA3处理能提高果实的细胞壁与细胞体积比,增加果实细胞壁物质,增大细胞壁中纤维素的比例[45,48],提高果实的硬度。Kuhn等[46]的研究表明,在樱桃转色期(S2 期)喷施GA3能够提高早熟及中熟樱桃品种成熟果实的硬度。笔者在本研究中发现,外源GA3对DB2-9 成熟期果实硬度无显著影响,而外施150 mg·L-1 GA3能够提高霞脆膨大期和成熟期的果实硬度。硬质桃在成熟期生长素(IAA)合成受阻导致乙烯不能正常释放[49],且外施GA3能降低樱桃果实发育过程中果实的IAA含量[50]。推测外施150 mg·L-1 GA3能抑制霞脆桃成熟期乙烯的释放,且这种作用对霞脆较DB2-9 强,造成了外源GA3对两个品种(系)成熟期果实硬度的不同影响。

采前外施GA3能够提高兔眼蓝莓果实的SSC[51]。本研究结果表明,外施GA3能提高DB2-9 和霞晖8号膨大期和成熟期果实的SSC,外施150 mg·L-1 GA3的霞脆成熟期果实SSC 显著高于其他各处理。本研究结果与前人的研究较一致。外源GA3能够提高果实库强,并提高果实中SDH 和SS 等糖代谢相关酶活性,从而提高果实中可溶性糖含量[52]。前人研究发现,对果树喷施GA3在提高成熟期果实可溶性糖含量的同时也会提高有机酸的含量[52-53]。一方面,外施GA3提高了DB2-9和霞晖8号成熟期果实总糖含量及3个品种(系)成熟期果实总有机酸含量,这与前人的研究结果一致。另一方面,在硬核期,3个品种(系)外施50、100 mg·L-1 GA3下果实的总糖含量低于对照(T1)、150 mg·L-1 GA3。同化物在苹果新梢速生期主要分配给新生的枝条和叶片[54],且较低浓度GA3能够促进果树的新梢生长[55],推测外源GA3抑制了同化物在硬核期向桃果实的运输,从而降低了果实的总糖含量。外施100、150 mg·L-1 GA3能显著提高3个品种(系)成熟期果实的总有机酸含量,这与前人的研究结果一致。外施GA3对3个品种(系)成熟期果实的糖酸比影响较小,这与外源GA3既能提高果实的可溶性糖含量又能提高有机酸含量有关。

4 结 论

不同桃品种(系)对外源GA3的响应不同,一定质量浓度的外源GA3能够显著提升不同桃品种(系)成熟期果实外观及内在品质(单果质量、总糖含量等)。DB2-9、霞晖8 号和霞脆的适宜外施GA3质量浓度分别为100、50和50 mg·L-1,研究结果将为外源GA3应用于桃果实品质提升方面提供理论依据和实际参考。

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Influence of exogenous gibberellin (GA3) on fruit quality in different peach varieties(strains)

CHEN Hong1,2, DU Jinhua1,2, MA Ruijuan2, ZHANG Yuanyuan2, DING Hui2, ZHANG Binbin2*, YU Mingliang2*
(1College of Horticulture, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China;2Institute of Pomology, Jiangsu Academy of Agricultural Sciences/Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement,Nanjing 210014,Jiangsu,China)

Abstract:【Objective】Exogenous GA3 is widely used to regulate fruit growth and development,which is closely related to fruit quality.The sensitivity of exogenous GA3 varies among different fruit tree species. The aim of this study was to investigate the effects of exogenous GA3 at different concentrations on single fruit mass, fruit shape index, colour values, firmness, soluble solids content (SSC), soluble sugar content, organic acid content, and sugar-acid ratio of different peach varieties (strains).【Methods】Peaches of DB2-9,Xiahui 8 and Xiacui were used as experimental materials.The experiment included 4 treatments:T1 (spraying water),T2 (50 mg·L-1 GA3),T3 (100 mg·L-1 GA3), and T4 (150 mg·L-1 GA3), and each treatment included three trees that were sprayed four times at intervals of 10 d, starting from 48, 50, and 46 d after full bloom, respectively. Twenty fruits were randomly collected from each treatment(three replications)at the hard core stage,expansion stage and ripening stage for the determination of external and internal fruit mass indexes.All data were statistically analyzed.【Results】In this study, the mass of single fruit of Xiahui 8 and Xiacui in T2 treatment was significantly higher than in the other treatments during the expansion and ripening stages; during the ripening period, the mass of single fruit of DB2-9 under T2 and T3 was significantly higher than under T1 and T4.During the expansion period, the shape index of DB2-9 and Xiacui in T1 was significantly lower than those in the other treatments;and during the three periods,the fruit shape index of Xiahui 8 in T2 was significantly lower than in the other treatments. During the expansion period, the L* value of DB2-9 and Xiacui in T3 and T4 was significantly lower than in T1;during the expansion and ripening periods,the L*value of Xiahui 8 in T2 was significantly higher than in T1.In the entire periods,the a*value of DB2-9 in T4 was significantly higher than in T1 and T2; at the ripening stage, the difference in the a* value of Xiahui 8 between treatments was not significant, and the a* value of Xiacui under T1 was significantly higher than under the other treatments.At the ripening stage,the C value of DB2-9 and Xiacui in T3 and T4 was significantly lower than in T1,while the differences among treatments were not significant in Xiahui 8.At the ripening stage,the a*/b*value of DB2-9 and Xiahui 8 under T3 and T4 was significantly higher than under T1 and T2,while the differences among treatments were not significant in Xiacui.During the ripening period,there was no significant difference in fruit firmness with skin and firmness without skin of DB2-9 among the treatments;during the expansion period,the firmness with skin and firmness without skin of Xiahui 8 in T4 was higher than in T1;during the three periods,the firmness with skin of Xiacui in T3 was significantly higher than in T1.The soluble solids content of Xiacui in T1 was higher than in the other treatments at the hard core and expansion stages, while the soluble solids content of DB2-9 and Xiahui 8 in T1 was significantly lower than in the other treatments at the expansion and ripening stages.The soluble sugar content of DB2-9 under T1 was significantly lower than under the other treatments during the expansion and ripening periods; the sucrose content, sorbitol content and total sugar content of Xiahui 8 under T2 were significantly lower than under T1 during the hard core stage, while they were significantly higher than under T1 during the ripening period;the soluble sugar content of Xiacui under T2 and T3 was lower than under T1 during the expansion period,while at the ripening stage,there was no significant difference in the glucose content, fructose content and total sugar content among the treatments in Xiacui.At the ripening stage, the quinic acid content and total acid content of DB2-9 under T1 were significantly lower than under the other treatments;at the hard core stage,the organic acid content of Xiahui 8 under T1 was significantly lower than under the other treatments,whereas the quinic acid content, malic acid content and total acid content of Xiahui 8 under T4 were significantly higher than under T1 at both the expansion and ripening stages; and at the ripening stage, the quinic acid content,malic acid content and total acid content of Xiacui in T3 and T4 were higher than in T1. In the expansion and ripening periods, the sugar-acid ratio of DB2-9 under T3 was significantly higher than under T1; in the ripening period, there was no significant difference in the sugar-acid ratio among the treatments in Xiahui 8;and the sugar-acid ratio of Xiacui under T2 and T3 was significantly lower than that under T1 and T4 in the three periods.【Conclusion】The application of 100 mg·L-1 GA3 significantly increased the mass of single fruit, SSC, total sugar content and sugar-acid ratio of DB2-9 at the ripening stage, while it had no significant effect on the pigmentation of the fruits; the exogenous application of 50 mg·L-1 GA3 increased the single fruit mass and SSC of Xiahui 8 at the three periods,as well as the total sugar content and sugar-acid ratio at the ripening stage, and significantly increased the L* value of the fruits at ripening; and the exogenous application of 50 mg·L-1 GA3 increased the mass of single fruit and firmness with skin of Xiacui in the three periods,as well as SSC and total sugar content in the ripening stage. Overall, the exogenous application of 100 mg·L-1 GA3 can improve the overall quality of fruits of DB2-9;the exogenous application of 50 mg·L-1 GA3 can improve the overall quality of fruits of Xiahui 8 and Xiacui.

Key words:Peach;GA3;Chilling requirement;Fruit quality

中图分类号:S662.1

文献标志码:A

文章编号:1009-9980(2025)04-0775-15

DOI:10.13925/j.cnki.gsxb.20240392

收稿日期:2024-08-07

接受日期:2025-01-13

基金项目:国家现代农业产业技术体系建设专项(CARS-30);江苏省现代农业产业技术体系建设项目(JATS[2023]387)

作者简介:陈鸿,男,在读硕士研究生,研究方向为桃栽培生理。E-mail:3223648874@qq.com

*通信作者Author for correspondence. E-mail:binbin1714@163.com;E-mail:mly@jaas.ac.cn