Articles
The effect of weather on the quality, productivity, and growth of pomegranates in the Mediterranean climate of the Western Cape in South Africa
Article number
1464_43
Pages
309 – 316
Language
English
Abstract
Pomegranate trees have a unique phonological character concerning flowering as compared to other deciduous fruit trees.
The flowering occurs three times, with the first flush, second, and third flush of the flowering period.
The three flowering periods are driven by weather variables such as temperature, relative humidity, radiation, and wind.
The harvesting is also dependent on the flowering timing, and this is also driven by the amount of chill units accumulated and the amount of heat units accumulated during the blooming period.
The fruit development is mainly dependent on radiation and temperature.
The fruits are more subjected to sunburn and therefore they are more sensitive to radiation.
The individual tree growth was determined based on the growth rates of new shoots on the trees over the 2022/23 and 2023/24 growing seasons for both young and full-bearing orchards.
The correlation between the daily tree individual growth rate and the most important weather variables was conducted on weekly campaigns.
The daily growth rates of shoots increased with increasing Rn, Tmax, Tmin, and VPD. A nonlinear trend described the relationship between leaf transpiration and VPD. The coefficient of determination for the nonlinear trend was 7.9 and 6.5% better compared to the linear trend for the young and full bearing orchard, respectively.
Growth rate for both orchards initially increased at a fast rate up to VPD of 1 kPa, after which it gradually decreased and tended to level off even more when the VPD became 3 kPa.
Detailed quality evaluation of fruit from the first and second flush harvests during 2023 for the young and full-bearing pomegranate orchards at Avontuur and Welgemoed, respectively, showed significant differences in terms of fruit weight, length, diameter, skin colour lightness, red colour, chroma, hue°, aril, total soluble solids, total titratable acidity, and pH are indicated.
Fruits on young trees were highly affected by the sun, as most of the fruits were barely covered or hidden by the leaves, as compared to the mature orchard.
It is recommended that pomegranate fruits be harvested for the export market mainly from full-bearing trees.
The flowering occurs three times, with the first flush, second, and third flush of the flowering period.
The three flowering periods are driven by weather variables such as temperature, relative humidity, radiation, and wind.
The harvesting is also dependent on the flowering timing, and this is also driven by the amount of chill units accumulated and the amount of heat units accumulated during the blooming period.
The fruit development is mainly dependent on radiation and temperature.
The fruits are more subjected to sunburn and therefore they are more sensitive to radiation.
The individual tree growth was determined based on the growth rates of new shoots on the trees over the 2022/23 and 2023/24 growing seasons for both young and full-bearing orchards.
The correlation between the daily tree individual growth rate and the most important weather variables was conducted on weekly campaigns.
The daily growth rates of shoots increased with increasing Rn, Tmax, Tmin, and VPD. A nonlinear trend described the relationship between leaf transpiration and VPD. The coefficient of determination for the nonlinear trend was 7.9 and 6.5% better compared to the linear trend for the young and full bearing orchard, respectively.
Growth rate for both orchards initially increased at a fast rate up to VPD of 1 kPa, after which it gradually decreased and tended to level off even more when the VPD became 3 kPa.
Detailed quality evaluation of fruit from the first and second flush harvests during 2023 for the young and full-bearing pomegranate orchards at Avontuur and Welgemoed, respectively, showed significant differences in terms of fruit weight, length, diameter, skin colour lightness, red colour, chroma, hue°, aril, total soluble solids, total titratable acidity, and pH are indicated.
Fruits on young trees were highly affected by the sun, as most of the fruits were barely covered or hidden by the leaves, as compared to the mature orchard.
It is recommended that pomegranate fruits be harvested for the export market mainly from full-bearing trees.
Authors
P.C. Tharaga, M. Ravuluma, R.L. Kgaphola, T. Volschenk
Keywords
quality, harvest, sunburn, fruit colour, flash flowering
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