Response of fruitset and other yield components to shoot topping and 2-chlorethyltrimethyl-ammonium chloride application

Abstract

Background and Aims:We investigated the effectiveness of shoot topping and 2-chlorethyltrimethylammonium chloride (CCC) application on the control of fruitset and other yield components on the grapevine varieties Cabernet Sauvignon, Chardonnay and Tempranillo at two sites over two or three seasons. Methods and Results: Treatments were applied before and during the flowering period. Fruitset and yield per vine increased in response to both shoot topping and CCC treatment, especially when shoot topping was applied between E-L stages 19 and 23, and when CCC was applied 1 week before flowering. All varieties at both locations responded to shoot topping to some degree: from 20 to 57% relative to the control for fruitset and from 16 to 97% for yield per vine. Conclusions: Fruitset, and, thus, yield, can be improved by cultural practices in all seasons, but the magnitude of the response may be greatest in those seasons when fruitset is lower than the average. Neither berry number per bunch nor the visual appearance of the bunches were reliable indicators of fruitset performance. Significance of the Study: Optimal timing of shoot topping and CCC application as cultural practices is critical to maximise the response. The 'Coulure Index' and the 'Millerandage Index', which are described for the first time, are novel and useful indicators of fruitset that have been developed to quantify the reproductive performance of grapevines. AbbreviationsCCC 2-chlorethyltrimethyl-ammonium chloride; CI Coulure Index; LGO live green ovary; MI Millerandage Index Keywords: CCC, Coulure Index (CI), fruitset, Millerandage Index (MI), shoot topping 256 Fruitset response to shoot topping and CCC

Differential fruitset between grapevine cultivars is related to differences in pollen viability and amine concentration in flowers

“…The proportion of flowers that abscise from an inflorescence before turning into a berry or a live green ovary (LGO) directly impacts fruitset and can be quantified using the coulure index (CI) (Collins and Dry ). The proportion of LGOs and seedless berries relative to seeded berries affects wine composition and is quantified using the millerandage index (MI) (Collins and Dry ). A higher level of coulure and millerandage commonly occurs in cultivars showing poor reproductive performance (Dry et al .…”

Assessment of flower number per inflorescence in grapevine by image analysis under field conditions

“…2 The reproductive performance, conducive to poor or good fruit set, has been reported to be variety and clone dependent 1,3,4 and impacted by physiological, environmental and pathological factors. 5 Fruit set rates have been estimated in various studies evaluating the effects of viticultural practices since the 19th century, 1,6 including late pruning, 7 shoot tipping, 8 topping, 9 early defoliation, 10 girdling 11 and spray applications of growth regulators 9,12 and nutrients. 13,14 In most of these studies, berry number per cluster was used to estimate fruit set and a sample of clusters was measured assuming that initial flower number per inflorescence was invariable between treatments.…”

Shoot topping of ‘Niagara Rosada’ grapevine grafted onto different rootstocks

“…The cluster fresh mass, length and width from the 'Karasakiz' (V. vinifera L.) were not influenced by the grapevine shoot topping (Dardeniz et al, 2008). In the same way, shoot topping showed no effect over the cluster fresh mass from 'Merlot' (V. vinifera L.) (Mota et al, 2010) and over the berries fresh mass from 'Chardonay' (V. vinifera L.) as well (Collins and Dry, 2009).…”

“…However, in some cases, this characteristic may increase significantly as a result of shoot topping in later cycles. The use of this practice in a productive cycle can affect the beginnings of inflorescence and, thus, the number of clusters during the next cycle (Collins and Dry, 2009).…”