Variation in Shiraz berry size originates before fruitset but harvest is a point of resynchronisation for berry development after flowering

Background and Aims:  Asynchronous berry development results in variation in berry size and berry composition. Variation in berry size affects vineyard yield, wine quantity and berry composition, while variation in berry composition affects fruit flavour and wine quality. The objective of this study is to identify when variation in berry size begins.
Methods and Results:  Shiraz bunches were sampled at seven stages throughout the growing season and the development of individual berries was characterised by measurements of weight, volume, surface area, deformability, seed number and seed weight. Coefficients of variation with respect to berry weight, volume and surface area were elevated throughout the post-flowering period but declined as the berries approached harvest ripeness.
Conclusions:  Variation in berry size originates prior to berry set, most probably during differentiation in the floral primordium at budburst. Harvest represents a point of resynchronisation in berry development when a number of physiological changes become synchronised between berries and within the bunch.
Significance of the Study:  Variation in berry size is presumed by the wine industry to have a negative impact on crop level, fruit composition and wine quality. Much of this presumption is scientifically unsubstantiated. The findings of this paper should encourage grapegrowers and winemakers to modify the timing of the harvest to coincide with a reduction in variation in berry size.     

The relationship between the expression of abscisic acid biosynthesis genes, accumulation of abscisic acid and the promotion of Vitis vinifera L. berry ripening by abscisic acid

Background and Aims:  Grapevines ( Vitis vinifera L.) are considered to have non-climacteric fruit, but the trigger initiating ripening (veraison) is poorly understood. This study aimed to further investigate the role of abscisic acid (ABA) during berry ripening.
Methods and Results:  In field-grown grapes over three seasons, free ABA levels increased at veraison then subsequently declined to low levels. Bound ABA increased as the free ABA level decreased after 10–11 weeks post-flowering (wpf), but ABA must also be degraded and/or exported. The absence of a large pool of bound ABA before veraison makes it unlikely that the increase in free ABA is due to the mobilization of conjugated ABA. The expression pattern of genes crucial for ABA synthesis, zeaxanthin epoxidase and two 9-cis-epoxycartenoid dioxygenases (NCEDs) indicates that berries may have the potential to synthesize ABA in situ . However, the expression profile of these genes did not correlate well with ABA levels indicating that ABA accumulation is under more complex control. The application of (+)-ABA advanced ripening as measured by colour formation, berry size increase and to a lesser extent sugar accumulation and altered the expression of one of the NCED genes.
Conclusions:  The changes in berry ABA levels around the time of veraison, which influence the timing of ripening, are under complex developmental control.
Significance of the Study:  The improved understanding of the control of berry ripening is vital to attempts to successfully manipulate this process.     

Changes in susceptibility of grape berries to splitting are related to impaired osmotic water uptake associated with losses in cell vitality

Background and Aims: High rainfall events after the onset of ripening commonly cause the skin of grape berries to split. The aim was to verify the suggestion, based on vineyard observations, that the susceptibility of grapes to splitting decreases during ripening, and to establish the role of cell vitality in this process. Methods and Results: The susceptibility of detached, ripening berries, cv. Shiraz, to splitting was assessed by immersing them in sucrose solutions or deionised water. At the onset of ripening, susceptibility to splitting was highest and decreased only slightly over 30 days. Thereafter, susceptibility decreased greatly until becoming negligible about 30 days later. Cell vitality within the pericarp, as determined by nitroblue tetrazolium staining, decreased from the onset of ripening. Conclusions: The reduction in the susceptibility of grape berries to splitting is attributed to a decrease in turgor-generating capacity within the berry as an increasing proportion of pericarp cells lose vitality. The loss of cell vitality corroborates previous evidence of this phenomenon, and indicates that this is a general feature of grape ripening. Significance of the Study: This study demonstrates the proportion of vital cells within the pericarp is the driver of turgor-induced splitting, in contrast to previous models in which the whole berry, enclosed in a semi-permeable skin, has been regarded as the osmotically functional system.     

圆叶葡萄种子发育过程中多酚积累特性

以栽培于广西地区2 个圆叶葡萄品种‘Noble’和‘Carlos’为实验材料,以真葡萄品种‘赤霞珠’和‘雷司令’为对照,使用超高效液相色谱-串联三重四极杆飞行时间质谱,分析其种子发育过程中多酚组成和积累特性。结果表明：在4种葡萄发育过程的种子样品中共检测到106种多酚,包括48种鞣花酸及前体物、24种黄酮醇、20种羟基苯甲酸、9种黄烷-3-醇、3种芪类和2种羟基肉桂酸。鞣花酸及前体物（主要是前体物）和黄烷-3-醇（主要是没食子酰化体和单体）分别是圆叶葡萄和真葡萄种子中最主要的多酚类型,但其含量在不同年份和品种间具有较大差异。前体物含量在圆叶葡萄‘Noble’幼果期种子中较高,然后逐渐下降,完全转色后再次上升;‘Carlos’则在浆果转色前种子中含量较高,随后略有下降。黄烷-3-醇在真葡萄‘雷司令’种子中2013年随着浆果发育含量显著升高,转色时含量达到最高,随后有所下降,2014年不受发育期的影响;‘赤霞珠’则分别在2013年幼果期和2014年果实完熟时的种子中含量最高。     

Grapevine fruit set: Physiology of the abscission zone

Effects of ethylene and of 'anti-ethylene' compounds on the floral pedicel abscission zone in grapevines were analysed via a laboratory model consisting of isolated flowers held in Petri dishes. Our model permitted precise determination of abscission and enabled us to test a range of physiologically-active compounds including ethylene precursors, and antagonists of ethylene action. For example, a precursor of ethylene, 1-aminocyclopropane-l-carboxylic acid, had the same effect as ethylene in promoting abscission. Conversely, an inhibition of ethylene action by silver thiosulfate or an inhibition of ethylene synthesis by amino-oxyacetic acid both strongly inhibited abscission zone function. The same type of effect can be obtained by increasing the proportion of auxin with regard to ethylene. The abscission zone of the isolated flower pedicel of grapevine conforms to the classic model of hormone-mediated operation of a pre-existing abscission zone. Our definition of hormone regulation holds practical implications for viticulture and offers new possibilities for controlling berry drop.     

Suitability of pre‐dawn and stem water potential as indicators of vineyard water status in cv. Tempranillo

Background and Aims: Irrigation management requires the collection of up‐to‐date information that allow growers to make rapid decisions, water potential being one of the most used parameters in irrigation scheduling. The goal of this research was to determine whether predawn (Ψpd) and stem (Ψs) water potential can be used equally well, quantifying the effect external factors have on the relationship between them. Methods and Results: Ψpd, mid‐morning (Ψs‐m) and noon (Ψs‐n) stem water potential were measured at seven cv. Tempranillo vineyards. Climatic conditions, vine growth and fruit load affected daily water potential dynamics. A greater decline of Ψs occurred when temperatures were higher and there was no dew formation, as well as under larger canopies and fruit load. While the relative impact of these variables on water potential was not particularly high, it was by no means negligible. Conclusions: Data collected in this study did not favour Ψpd, Ψs‐m or Ψs‐n as a preferred measure to evaluate plant water status. It is important to remark that similar Ψpd values do not necessarily indicate the same level of deficit, and that similar Ψs values do not always mean similar water availability. Therefore, a straightforward interpretation of Ψpd and Ψs can sometimes be misleading. Significance of the Study: The results obtained provide significant explanation to the lack of agreement in the literature regarding the most suitable time to measure water potential. Vineyard managers and scientists should select it according to the level of stress expected, climatic conditions and irrigation frequency.     

上海地区主栽葡萄品种品质评价与分析

目的 评估上海地区主栽葡萄品种的品质差异, 明确关键品质指标。方法 本研究选取了上海地区7家种植企业的10个主要葡萄品种, 共采集34批次样品。通过分析穗质量、粒质量、果糖、葡萄糖、总酸、维生素C、氨基酸、花青素等12项指标, 从外观物理性状、内在营养品质和综合品质3个方面对葡萄品质进行评估。结果 葡萄品种在外观物理性状、内在营养品质及综合品质方面存在显著差异(P<0.05)。阳光玫瑰在糖酸平衡方面表现突出, 醉金香具有较高的维生素C和综合营养品质, 巨玫瑰在葡萄糖含量上优势明显, 申园的氨基酸总量最高, 但其氨基酸比例需优化。综合分析表明, 糖酸比例、氨基酸组成和果实重量是决定葡萄品质差异的主要因素。结论 上海地区主栽葡萄品种在品质特性上各具优势, 阳光玫瑰、醉金香和巨玫瑰适宜推广作为高端鲜食葡萄。研究结果为葡萄品种选育、种植管理及市场定位提供了科学依据, 并为消费者健康及功能性食品开发提供参考。