Net CO₂ Assimilation and Carbohydrate Partitioning of Grapevine Leaves in Response to Trunk Girdling and Gibberellic Acid Application

Abstract

Leaf net CO2 assimilation rate (A), stomatal conductance (g,), carboxylation efficiency, and foliar nonstructural carbohydrates were measured on mature, field-grown Vitis vlnffera L. (cv Thompson Seedless) vines that had been trunk girdled, sprayed with gibberellic acid, or both, shortly after anthesis. Girdling reduced A, g9, and carboxylatfon efficiency when measured 2 weeks after imposition of the treatments. Diumal measurements indicated that A of girdled vines was less than that of control vines between 1000 and 1800 hours. Gibberellic acid mitigated the depressing effect of girdling on g. during the same diumal measurements. The concentrations of foliar carbohydrates were greatest for the girdled vines, followed by the combination treatment and were lowest for the control vines. Foliar carbohydrates were greater for girdled vines 4 weeks after the treatments were imposed, however, by this time there was no significant difference in A between the control and girdled vines. Two and 4 weeks after the experiment was initiated root carbohydrate concentrations were less for the girdled vines when compared to the control vines. The data indicate that the reduction in A of girdled grapevines is not associated with the accumulation of leaf nonstructural carbohydrates following the girdling treatment.Alteration of the plant's source/sink relationships commonly occurs in the production of perennial horticultural crops. This is especially true for the production of seedless table grapes in California. Cultural practices used for table grape production include the use of GA3 sprays at anthesis which reduces the number of flowers that set and then an additional GA3 spray shortly thereafter which will increase berry size. Trunk girdling (the removal of a ring of phloem) also is utilized shortly after anthesis to increase berry size or later in the season to enhance fruit maturity (earlier berry coloration or accumulation of sugar). Other practices include the removal ofentire clusters or portions ofindividual clusters which will increase the size of remaining berries. Many times girdling and GA3 sprays are used together shortly after anthesis as they have a synergistic effect on increasing berry size (9). These types of results indicate that the grapevine would be an excellent system in which to study the effects of source/sink '

Physiological responses of kiwifruit vines (Actinidia chinensisPlanch. var.chinensis) to trunk girdling and root pruning

“…Correctly applied girdles should not cause substantial damage to the xylem and should therefore not directly affect hydraulic conductance. In grape, reductions in stomatal conductance have been observed following trunk girdling (Roper & Williams 1989;Williams et al 2000), although this was not associated with reductions in leaf water potential (Williams et al 2000), which suggests a photosynthetic rather than hydraulic response. In oak, however, trunk girdling reduced xylem sap flux within 2 days of treatment (De Schepper et al 2010).…”

Effects of cane girdling on yield, fruit quality and maturation of (Vitis vinifera L.) cv. Flame Seedless

“…Vines are girdled in an attempt to improve fruit setting, maturation, quality and yield parameters [7,[17][18][19]. Girdling practices cut the movement in the phloem and change the hormonal balance [12].…”

“…Increment in berry size owing to girdling is result of better carbohydrate nutrition above the girdle because the transport of sugars from leaves to the root system is blocked by girdling treatment [7]. Also changes in the hormonal balance of the grapevine after girdling may cause an increament on berry size [12].…”

“…There are so many factors which affects grape quality directly during the grape growing; such as pruning, crop load, thinning, girdling, topping, pinching and using of plant growth regulators [7]. In other words quality, quantity and nutritoanal value of grape is under the influence of some agricultural practices and techniques.…”

“…It has been practiced for many years to provide bigger berries in terms of table grape production or to provide fruit maturity by enhancing berry coloration or accumulation of sugar [7][8][9]. Also physical characteristics of grapes such as colour, form and shape are so important attributes for consumers [10,11].…”