List of Titles

Study on the effect of shade net on internal and external quality parameters and chilling injury of fruits of citrus species in the Eastern Cape Province of South Africa

- Moabelo, Phillipine https://orcid.org/0000-0001-9040-1390

Authors: Moabelo, Phillipine https://orcid.org/0000-0001-9040-1390
Date: 2021-11
Subjects: Fruit-culture , Horticulture , Citrus fruits
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10353/22622 , vital:52600
Description: Pre-harvest technology of shade net is environmental friendly and was found previously to improve fruit growth and yield. In addition, it reduces wind blemishes and sunburn, and effectively act as a buffer against climate fluctuations, such as excessive light, wind and hail damages. However, commercial shade nets are capital intensive; therefore, it is important for farmers to understand its impact on fruit quality that is desired for export market and assess whether the investment is profitable to the industry or not. It was brought to attention that several citrus cultivars grown in Addo, Eastern Cape under 20percent commercial shade net shows sensitivity to chilling injury (CI); however. no information is yet documented about the impact of this technology on fruit quality. To determine the efficacy of 20percent-shade net technology in relation to the control (no shade net), the present study was designed with the objective to compare internal and external quality parameters of ‘Washington and Cambria’ navels, ‘Valley Gold’ mandarin, and ‘Eureka’ lemon fruit grown in shade netted orchards and stored at low temperatures (4 and -0.6°C) for 30 days in Addo area, Eastern Cape. Internal quality attributes assessed includes juice content, °Brixpercent, titratable acid (TA), °Brix:acid ratio and average number of seeds. External quality data assessed include rind colour, and fruit size, firmness/texture and fresh weight loss. For chilling injury, fruits were evaluated by examining the degree of rind pitting and assigning levels of severity namely 0, 1, 2 or 3 where 0 = no pitting detected, 1 = 1 pit, 2 = 2 or more pitting detected and 3 = severe pitting detected. The post-harvest experiments were done on fruits harvested from commercial citrus orchards in Sundays River Valley, between Kirkwood and Addo (33° 34' 0" South, 25° 41' 0" East), in the Eastern Cape Province of South Africa, over two harvesting seasons (2018 and 2019). The ‘Eureka’ lemon and ‘Washington navel’ fruit were collected from Allendale farm; the ‘Cambria’ navel fruits from the Nuwelande and Olifantsbos farms; and the ‘Valley Gold’ mandarin fruits from the Dunbrody/Unifruitti farm. The quality attributes were recorded in the Laboratory of the Citrus Research International (CRI), Port Elizabeth, Eastern Cape, South Africa during Season 1, and in the Horticulture lab of the University of Fort Hare (UFH), Alice, Eastern Cape, South, Africa during Season 2. The experimental layout was a typical pseudo randomised completely block design (RCBD) (not truly randomised) whereby treatments tested were subjected over time (pre-test, post-test). The two treatments i.e. shade vs. control (no shade net) could not be randomly allocated to orchards due to the practical issue of working on a commercial farm, . The sub-factor consisted of three postharvest treatments: Ambiemt temperature (at 0 days storage), 4°C and -0.6°C storages for 30 days. Secondly, an experiment to evaluate the impact of petroleum-based wax mixed with 2-(4-thiazolyl) benzimidazole [thiabendazole (TBZ)] (TBZ: 500 mg.L-1) on shade net vs control fruits was conducted. The fruits were stored at 4°C and - 0.6°C (coated) for 30 days and were evaluated after 7 days storage at room temperature. Shade net did not significantly affect the internal quality attributes of citrus fruits. The 20percent- shade net promoted size of ‘Washington’, ‘Cambria’ navels and ‘Valley Gold’ mandarin, whilst rind colour was not affect. Firmness loss was higher on ‘Eureka’ lemon and ‘Washington’ navel, regardless of the growing conditions and cold storage duration. Rind firmness of ‘Cambria’ navel and ‘Valley Gold’ mandarin were not significantly affected by shade net and storage duration. ‘Eureka’ lemon was found to be more sensitive to CI. However, the application of wax+ TBZ eliminated CI on all 4-cultivars. Therefore, it is recommended to apply wax+ TBZ in packline to eliminate CI and fungal development. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
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Date Issued: 2021-11

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Horticultural propagation of the threatened species, Syncarpha revurvata (L.f.)B. Nord

- Swart, Pierre André

Authors: Swart, Pierre André
Date: 2006
Subjects: Horticultural crops -- Propagation , Plant propagation , Horticulture
Language: English
Type: Thesis , Masters , MSc
Identifier: vital:10624 , http://hdl.handle.net/10948/613 , Horticultural crops -- Propagation , Plant propagation , Horticulture
Description: Syncarpha recurvata (L.f.) B. Nord. (Asteraceae, Gnaphalieae) is listed as a vulnerable (intermediate priority) species. The propagation methods of achene germination, stem cuttings, air layering and micropropagation were investigated to obtain an efficient propagation method. Smoke water dilutions of 1:100, 1:50 and 1:10 significantly increased germination, with the 1:100 smoke water dilutions showing the highest germination percentage (22.4 percent). Achenes collected between August and October 2005 showed higher germination and viability than achenes collected between May and July 2006. Fifty percent of the stem cuttings and 32 percent of the airlayered branches rooted. Embryo culture was the only successful culture type out of the four attempted. Two embryos germinated and four became photosynthetic. Two of the germinated embryos also produced callus cells, a medium supplemented with 5 μM IAA may be used to test for a suitable plant regulator for organogenesis or embryogenesis. Syncarpha recurvata plants were also transplanted into pots and 60 percent survived. A growth rate of 1.466 mm y-1 was obtained from total shoot length measurements. In this study, it was found that air-layering branches of transplanted Syncarpha recurvata plants is the most efficient propagation method.
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Date Issued: 2006

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