Grapevine (Vitis vinifera, cultivar: Crimson Seedless) canes were collected from the 9-year-old Vitis vinifera Crimson Seedless block of the Laborans farm of the JD Kirsten Trust (Paarl, South Africa). The vineyard uses the open gable trellis design, and all Crimson Seedless vines are grafted onto Ramsey rootstocks.
Table 3.3.1. Vineyard block details for the Crimson Seedless block on the Laborans (Paarl, South Africa).
| Characteristics | Laborans Farm | Welgevallen Farm |
|---|---|---|
| Block number | 92 | ? |
| GPS coordinates | -33.666784; 18.944941 | ? |
| Cultivar | Crimson Seedless | Crimson Seedless |
| Rootstock | Ramsey | Ramsey |
| Year planted | 2016 | ? |
| Area | 6ha | ? |
| Spacing | 1735 vines/ha | ? |
| Trellis system | Gable | Gable |
| Irrigation | Micro-sprinkler | ? |
| Overhead nets of plastic | No | ? |
Dormant canes in E-L stage 1 were collected from two middle rows (row 25 and 26) of the CS block on the 2nd of May 2025. At the date of sampling, 15.5 CUs were accumulated. Canes were transported and temporarily maintained in plastic bags with their “feet” kept in tap water. Sixty canes were sampled – thirty from row 25 and thirty from row 26. From each row, three canes per vine were sampled for ten vines (vines 1, 7, 13, 19, 25, 31, 37, 43, 49, 55). Each vine was located 6 vines after the previous vine. From each vine, one cane was selected as a biological replicate for metabolic and cell wall analyses. The remaining two canes per vine were used as biological replicates for forced bud break assays where one cane acted as negative control (distilled water was used as breaking agent during the assay) and the other for treatment with hydrogen cyanamide (HC 3%).
Local weather data were acquired from the 200 4G weather station (Hortec, Somerset West, Western Cape, South Africa, https://www.hortec.co.za/) (accessed on 22 September 2022, which is located on Môrewag farm, Paarl (approx. 3.6 km from the experimental site). Sampling dates for 2025 were determined by assessing the total accumulated chilling by vineyards as chill units that were calculated using the Infruitec model. This model is commonly used by local farmers and industry experts in the Western Cape, South Africa.
All canes were cut into ten single-node-cuttings (SNCs) per cane, thus producing a total of 400 SNCs. Importantly, each SNC cutting represents a compound bud and when referring to treatments of SNCs hereafter, it is implied that the actual compound buds received the same treatment, unless stated otherwise. The position of the bud along the cane were . SNCs were dipped in contact fungicide (Sporekill – 1 ml/L tap water) and drained for a few minutes. The exposed buds were then either dipped in tap water or Dormex (HC 3%) before being placed in stryfam supports that were floated on tap water in plastic trays at a bud-break forcing temperature of 25 oC, with a 16’8 h light/dark photoperiod and light intensity of 35 µmol/m2/2. Temperature was monitored with Tinytag TGP-4500 loggers. For each vine, the two canes used for negative and positive controls, were grouped next to each other, and all ten SNCs per vine were positioned from the bottom to tenth bud from bottom to top of the support.
The location of biological replicates of different vines experiencing different chilling accumulation were randomised along the horizontal plane of the Styrofoam supports. In total, there were 16 supports each having 7 dual-columns with 10 SNCs for negative control in one sub-column and the 10 SNCs for Dormex in the adjacent sub-column. The water in the trays were replaced every 7 days. All laboratory equipment were rinsed with Sporekill before use. The SNCs were monitored for bud-break daily, with the bud-break date being defined as the date at which green tissue became visible underneath the bud scales. More, specifically, this is defined as E-L stage 3 and E-L stage 4.