Effect of Nitrogen application , leaf age, and drying method on growth, yield and quality of sweet potato
- Authors: Joko, Lungisa Banathi https://orcid.org/0000-0002-6369-7146
- Date: 2023-05
- Subjects: Nitrogen in agriculture , Sweet potato leaves , Sweet potatoes -- Harvesting
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/28244 , vital:73957
- Description: Root crops, such as sweet potatoes, are important sources of carbohydrates in the pacific region where soils are generally of inferior quality. Sweet potato leaves are said to be more nutritious when compared with storage roots, therefore can be used as a source of nutrition by human beings. Sweet potatoes like other vegetables are perishable and therefore they need to be processed in order to increase storage life. The shelf life of perishable vegetables can be increased by the use of drying methods. This brings an opportunity area for research to realize the full potential of sweet potatoes. Sweet potatoes can be developed as a sustainable crop for diverse nutritionally enhanced and value-added food products to promote human nutrition. Thus, the study sought to develop nitrogen level that could result in maximum yield of tubers while the green leaves are harvested for human consumption. The study also sought to find the best suitable drying method to extend the shelf life of orange-fleshed sweet potatoes OFSP leaves. The research was conducted at the University of Fort Hare glasshouse, Alice, in the Eastern Cape Province of South Africa. OFSP plants were grown at the UFH research farm, harvested and sorted according to their different age groups. The leaves were then taken to the glasshouse for the experiment to be conducted. The first experiment followed CRD 4x3 factorial replicated 3 times, with 4 levels of leaf age (upper, middle, lower, basal) and 3 levels of drying sun, shade, oven. The second experiment followed a RCBD replicated five times, with 4 levels of N 50 100 150, and 200 kgha randomly allocated. All the nutritional analysis was done based on the recommendations by the Association of Official Chemists A.O.A.C. Statistical analysis was done using SAS, Version 9.1. Where a significant difference was detected, variable means were separated using Fisher’s protected least significant difference p 0.05. , Thesis (MSc) -- Faculty of Science and Agriculture, 2023
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- Date Issued: 2023-05
Effects of sustained elevated CO2 concentration and Nitrogen nutrition on wheat (Triticum aestivum L. cv Gamtoos)
- Authors: Kgope, Barney Stephen
- Date: 2000
- Subjects: Wheat -- Growth , Wheat -- Nutrition , Nitrogen fertilizers , Nitrogen in agriculture
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4205 , http://hdl.handle.net/10962/d1003774 , Wheat -- Growth , Wheat -- Nutrition , Nitrogen fertilizers , Nitrogen in agriculture
- Description: There is consensus that high CO2 results in enhanced growth and yield for most crop plants. However, most of these studies were carried out in the presence of adequate nutrients, which is also the case in agricultural systems (managed ecosystems). About 20% of the earth’s land mass have sufficiently low levels of nutrients to cause some kind of stress to plants. On the other hand, elevated [CO2] decreases foliar nutrient elements in plants and as a result partitioning of certain nutrient elements in plants is altered. Little data is available on the partitioning of most nutrient elements in plants, and this will definitely impact on growth and yield. To investigate this, wheat (Triticum aestivum L. c.v. Gamtoos) was grown in controlled environment cabinets at 360 and 700 µmol mol -1 CO2. The full Long-Ashton nutrient solution comprising of three-nitrogen concentrations ([N]) viz. (4,6 and 12 mM) was used to water plants everyday. The measurement of net assimilation rate (NAR), stomatal conductance (gs), transpiration rate (E), water use efficiency (WUE), foliar [N], nitrogen use efficiency (NUE) and growth parameters (total plant biomass (TPB), total plant height (TPH), leaf area (LA), shoot and root dry weight) were made 7 days after germination (7 DAG) till the onset of flowering. The increase in nitrogen supply in the order of 4, 6 and 12mM resulted in an increase in NAR, g_s_ , WUE and a decline in E under elevated [CO2]. Under elevated [CO2] NAR was observed to increase during the first two weeks reaching its maximum at 14 DAG, thereafter followed by a decline reaching its maximum at 28 DAG. This was later followed by an increase at 35 DAG onwards. Under elevated [CO2], NAR was increased significantly between the nitrogen regimes during the first (7-14 DAG) and the last two (35-42 DAG) weeks. The response of assimilation as a function of internal [CO2] (Ci), showed a decrease with age at ages 14, 28 and 35 DAG. This negatively affected the initial slope and the CO2 saturated photosynthetic rates under all treatments. This suggest that acclimation may have been as a result of both stomatal and biochemical limitations. All the photosynthetic pigment levels (chl_a_, chl_b_, chl_(a+b)_, and C_(x+c)_ ) increased with an increase in nitrogen supply from 4 to 6mM [N]. A 12mM [N] resulted in a significant decline in the photosynthetic pigment levels compared to a 6mM [N]. Chla remained higher than chlb under all treatments. Also, NAR was seen to increase and decrease concomitantly with the photosynthetic pigment levels. Foliar [N] was seen to decrease with an increase in nitrogen supply from 4 to 6 mM [N] under elevated [CO2] and the effects were adverse under the 4mM [N]. Under the 6mM N regime foliar [N] was positively correlated to NAR for elevated [CO2] grown plants. Similarly, E was positively correlated to foliar [N] under the same conditions. Elevated CO2 and increase in nitrogen supply had a pronounced effect on total plant height (TPH), total plant biomass (TPB), leaf area (LA), shoot and root dry weight and nitrogen use efficiency (NUE). The effects were more pronounced under a 6mM [N] as a result of high NUE. However, under 12mM [N] growth was not as expected as a result of lower NUE. Under all treatments shoot dry weight (SDW) was positively correlated to NUE. Anatomical studies revealed that total leaf and midrib thickness was significantly increased with an increase in nitrogen supply under elevated CO2 to support the larger leaf areas. There were no significant changes in the chloroplast ultrastructure as a result of the increase in nitrogen supply and CO2 enrichment. Starch grain surface area was seen to decline with an increase in nitrogen under both ambient and elevated CO2. Elevated CO2 and increase in nitrogen supply significantly increased total grain dry weight per plant by 47 and 46% respectively under 6 and 12mM [N]. In contrast, the increase was by about 21, 61 and 67% respectively under 4, 6 and 12mM [N] between the CO2 regimes.
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- Date Issued: 2000