Impacts of climate change on accumulated chill units at selected fruit production sites in South Africa

Tharaga, P.C.; Steyn, A. Stephan; Coetzer, G.M.

doi:10.17660/actahortic.2016.1130.9

Cited by 5 publications

(4 citation statements)

References 95 publications

(201 reference statements)

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“…Rising global winter temperatures due to climate change are an increasing threat to agricultural practices globally, continuously introducing abiotic stress at a pace too rapid to allow for evolution and adaption [69]. Average winter temperatures have increased annually and are predicted to continue rising all over the world, including grape-producing regions in South Africa [8,13,70,71]. This is in accordance with the lower CUA accumulated in 2022 than in 2021 in the experimental site, which was in the Berg River table grape- Together, the abovementioned components should ideally induce dormancy-release and aid in cell recovery in the following ways.…”

Section: Discussionmentioning

confidence: 99%

“…Regardless of cold accumulation in South Africa, farmers apply HC to guarantee high bud-break percentages and rapid and uniform dormancy release in their vineyards [4]. The need for the use of HC by fruit growers is predicted to increase with the effects of climate change and a general warming of growing regions [13]. HC is toxic, and its use has either already been banned or is predicted to be banned in several countries [14].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Plant Biostimulants Enhance Bud Break in Vitis vinifera Crimson Seedless Using Combination Treatments

Venter,

Avenant,

Kotze

et al. 2024

Horticulturae

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The rest-breaking agent, hydrogen cyanamide (HC), can substitute insufficient chill unit accumulation in Vitis vinifera and induce uniform bud-break; however, due to its toxicity it is being banned. In South Africa, red seedless grapes, including V. vinifera Crimson Seedless (CS), are the largest table grape export group; therefore, replacing HC in V. vinifera CS is crucial. This study aimed to confirm the molecular triggers induced by HC and assess the bud-break-enhancing abilities of commercial plant biostimulants. Forced bud-break assay experiments using V. vinifera CS single-node cuttings and a small-scale field trial were performed. Results demonstrated that increased chill unit accumulation (CUA) reduced HC efficacy. Bud-break started between 10 and 20 days after treatment, irrespective of final CUA. The small-scale field trial found that HC 3% and biostimulants were similar to the negative control. The treatment of dormant grapevine compound buds with nitric oxide (NO), hydrogen peroxide (H2O2), and hypoxia trigger dormancy release to a certain extent, supporting the molecular models proposed for HC action. NO, H2O2, and hypoxia, in combination with PBs, may potentially replace HC; however, this needs to be confirmed in future experiments.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Plant Biostimulants Enhance Bud Break in Vitis vinifera Crimson Seedless Using Combination Treatments

Venter,

Avenant,

Kotze

et al. 2024

Horticulturae

View full text Add to dashboard Cite

show abstract

“…Rising global winter temperatures due to climate change are an increasing threat to agricultural practices globally, continuously introducing abiotic stress at a pace too rapid to allow for evolution and adaption [69]. Average winter temperatures have increased annually and are predicted to continue rising all over the world, including grape-producing regions in South Africa [8,11,70,71]. This is in accordance with the lower CUA accumulated in 2022 than in 2021 in the experimental site, which was in the Berg River table grape-producing region of South Africa (Figure S4).…”

Section: Discussionmentioning

confidence: 99%

Plant Biostimulants Enhance Bud Break in Vitis vinifera Crimson Seedless

Venter,

Avenant,

Kotze

et al. 2024

Preprint

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The rest-breaking agent, hydrogen cyanamide (HC), can substitute insufficient chill unit accumulation in Vitis vinifera and induce uniform bud-break; however, due to its toxicity it is being banned. In South Africa, red seedless grapes, including V. vinifera Crimson Seedless (CS), are the largest table grape export group; therefore, replacing HC in V. vinifera CS is crucial. This study aimed to confirm the molecular triggers induced by HC and assess the bud-break-enhancing abilities of commercial plant biostimulants. Forced bud-break assay experiments using V. vinifera CS single-node cuttings and a small-scale field trial were performed. Results demonstrated that increased chill unit accumulation (CUA), reduced HC efficacy. Bud-break started between 10 and 20 days after treatment, irrespective of final CUA. The small-scale field trial found that HC3 % resulted in a slightly delayed bud-break rate, whilst biostimulants were similar to the negative control. The treatment of dormant grapevine compound buds with nitric oxide (NO), hydrogen peroxide (H2O2), and hypoxia trigger dormancy-release to a certain extent, supporting the molecular models proposed for HC action. NO, H2O2, and hypoxia, in combination with PBs, may potentially replace HC; however, this needs to be confirmed in future experiments.

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“…Apple cultivars with a high chilling requirement also have a high heat requirement, which may be advantageous in avoiding late frost damage after bud break in spring [27]. Chilling requirements (Table 1) differ between different cultivars [28], but they also vary significantly between cultivars originating in different parts of the world [20].…”

Section: Introductionmentioning

confidence: 99%

Climate Change Impacts on Temperature and Chill Unit Trends for Apple (Malus domestica) Production in Ceres, South Africa

2021

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Climate is an essential part of crop production, determining the suitability of a given region for deciduous fruit products such as apples (Malus domestica). It influences the yield and quality of fruits. There is strong evidence of global and regional-scale climate change since the advent of the industrial era. In South Africa, mean surface temperatures have revealed a warming trend over the last century. This study aimed to assess the impact of climate change on temperature and chill unit trends for apple production in Ceres, South Africa. The daily positive Utah chill units (DPCU) model was used as frequent high temperatures can lead to a high negation volume. Historically observed (1981–2010) and future projected (2011–2100) temperatures were obtained from the South African Weather Service (SAWS) and three ensemble members of the Cubic-Conformal Atmospheric Model (CCAM), respectively. The latter employed the RCP8.5 pathway. Linear trends were calculated for temperature and accumulated PCUs for the historical base period. The probability of accumulating specific threshold PCU values for both historical and future periods was assessed from cumulative distribution functions (CDFs). The historical change in minimum temperatures showed no significant trend. Ceres revealed a warming trend in maximum temperatures over the historical period. By the 2080s, the probability of not exceeding a threshold of 1 600 PCUs was exceptionally high for all ensemble members. Future projections showed a decline in the accumulated PCUs of 2–5% by the 2020s, 7–17% by the 2050s, and 20–34% towards the end of the 20th century. Based on these results, it is clear that winter chill units are negatively influenced by climate change. The loss in yield and fruit quality of apples due to climate change can negatively impact the export market, leading to significant economic losses for apple production in the Ceres area.

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Impacts of climate change on accumulated chill units at selected fruit production sites in South Africa

Cited by 5 publications

References 95 publications

Plant Biostimulants Enhance Bud Break in Vitis vinifera Crimson Seedless Using Combination Treatments

Plant Biostimulants Enhance Bud Break in Vitis vinifera Crimson Seedless Using Combination Treatments

Plant Biostimulants Enhance Bud Break in Vitis vinifera Crimson Seedless

Climate Change Impacts on Temperature and Chill Unit Trends for Apple (Malus domestica) Production in Ceres, South Africa

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