Theses and Dissertations
https://hdl.handle.net/13049/10
2024-03-28T14:35:32ZEffect of nitrogen fertilizer and planting density on the growth and yield of intercropped sorghum and cowpea under rainfed conditions
https://hdl.handle.net/13049/724
Effect of nitrogen fertilizer and planting density on the growth and yield of intercropped sorghum and cowpea under rainfed conditions
Mosupiemang, Marang
Cereal-legume intercropping can be an alternative for smallholder farmers to mitigate the effects of climate change and to promote sustainable agricultural production. A field experiment was conducted at BUAN gardens during the 2015/2016 planting season to assess the effect of nitrogen fertilization, planting density and cropping system on the growth, yield and nutrient uptake of sorghum and cowpea. The experiment was arranged in a split-split plot design with five levels (0, 50, 75, 100, 125 kg N/ha) of lime ammonium nitrate (LAN) fertilizer as the main plot (with plants that received 0 kg N/ha being control plants), three cropping systems (sole cowpea, sole sorghum and intercrops) as sub plots and three planting densities (40 000, 53 333 and 66 667 plants/ha) as sub-sub plots. The results have shown that LAN application had little effect on the growth, yield and nutrient uptake of cowpea. The control cowpea plants had significantly (p ≤ 0.01) higher photosynthetic rates irrespective of planting density and cropping system. They also exhibited the highest stomatal conductance, WUE, nodule number, nodule biomass, root and shoot biomass and therefore higher nutrient uptake. Planting at a density of 53 333 plants/ha significantly (p ≤ 0.01) increased photosynthetic rate in cowpea. Intercropped cowpea had significantly lower nodule biomass, lower WUE and increased transpiration rates. Planting cowpea at a higher density of 66 667 plants/ha significantly (p ≤ 0.05) increased its WUE but decreased the uptake of some nutrients. In sorghum N application increased growth, yield and nutrient uptake. Nitrogen application rate of 50 kg/ha increased shoot and root biomass, NUE and nutrient uptake in sorghum. Intercropped sorghum had significantly higher photosynthetic rates and lower NUE than monocropped sorghum. The control sorghum plants showed significantly higher photosynthetic rates with intercropped plants exhibiting higher values. However, there were no significant differences in the yield of sorghum whether it is among the various levels of LAN applications, between the cropping systems or among different planting densities. Similar to sorghum, all treatments did not lead to any increase in the yield of cowpea grain. In conclusion, the 2015/2016 cropping season was not a normal one due to the extreme soil temperature. Thus, increased growth, biomass yield and nutrient uptake in cowpea and sorghum caused by the interaction between LAN application and planting density did not translate to increased grain yields. Intercropping sorghum with cowpea was efficient than monocropping in resource utilization as shown by LER value that is greater than one. It is recommended that more leguminous plants with high nitrogen fixing capability should be included to fix more nitrogen and reduce fertilizer cost by smallholder farmers. Modelling should be included to help policy makers in planning to assist farmers on improving crop production to increase food security in a sustainable manner.
2017-11-01T00:00:00ZEffect of compost amendments on soil physicochemical properties, plant growth and efficient use of water, nitrogen and phosphorus in maize (zea mays l).
https://hdl.handle.net/13049/723
Effect of compost amendments on soil physicochemical properties, plant growth and efficient use of water, nitrogen and phosphorus in maize (zea mays l).
Ndubo, Orata Tshomarelo
Compost is used across the world to sustain soil fertility and crop yield. This investigation consists of two experiments, which were conducted at BUAN greenhouses and farmers field in the Central District of Botswana in the period November 2018 to April 2019 involving maize (Zea mays.L). The experiments were carried out to test the hypotheses that soil amendments with compost as organic fertilizer improved soil physico-chemical properties, plant growth, WUE, NUE and PUE of maize under irrigated and drought stressed conditions. A completely randomized block design was used with the following treatments; (1) Soil + Urea (SU), (2) Soil + Urea + Compost (SUC), (3) Soil + Compost (SC), (4) and Soil (Control) replicated four times. The treatments for greenhouse trial comprised of two levels of irrigation, (W1= stressed at flowering stage, W2= irrigated). Data was collected on soil physico-chemical properties, plant growth, water use efficiency (WUE), nitrogen use efficiency (NUE) and phosphorus use efficiency (PUE). The results showed that compost amendments significantly increased soil pH, EC, CEC, total carbon, total N, available P and cation exchange capacity (CEC). This study also revealed that WUE improved in stressed plants compared to irrigated plants; drought stressed treatments were more water use efficient than the irrigated treatments. PUE and NUE in SC and SUC were maintained higher than in control and SU under both conditions. The highest NUE 24.66kg/kg was exhibited for SUC treatments under irrigated condition as compared to the rest of the treatments. Moreover, SUC and SC recorded the highest PUE 210.35kg/kg and 141.89kg/kg under irrigated condition and 24.71kg/kg and 20.37/kg/kg under drought stressed condition respectively. In conclusion combination of compost and urea fertilizer significantly enhanced NUE, PUE and WUE in maize. These could decrease the amount of fertilizer and water-use required for the sustainable production in maize under unstressed and stressed environment
2023-05-01T00:00:00ZFarmers’ knowledge of the carmine spider mite, Tetranychus cinnabarinus Boisduval (Acari: Tetranychidae), its susceptibility to acaricides and activities of detoxifying enzymes in Botswana
https://hdl.handle.net/13049/722
Farmers’ knowledge of the carmine spider mite, Tetranychus cinnabarinus Boisduval (Acari: Tetranychidae), its susceptibility to acaricides and activities of detoxifying enzymes in Botswana
Legwaila, Mosimanegape Mitch
Tomato (Solanum lycopersicon L.) is an important vegetable due to its nutritional and economic value. It’s production has become very difficult and costly due to the prevalence of pests and diseases. Spider mites are among the most damaging pests of tomato in Botswana. The overarching objective of this study was to assess farmers’ knowledge of the carmine spider mite, Tetranychus cinnabarinus Boisduval (Acari: Tetranychidae), its susceptibility to acaricides and activities of detoxifying enzymes in Botswana. An oral questionnaire was used to evaluate farmers’ knowledge, perceptions and management of the carmine spider mite (CSM) on tomato in Botswana. The second study evaluated the effectiveness of selected pesticides for the control of CSM in Botswana. In a third study, the economic injury levels and yield loss were assessed for CSM on tomato. The fourth study evaluated pesticide detoxification enzyme activities in CSM strains collected from different locations in Botswana. The results of the survey showed that most farmers (75.7%) identified spider mites as a major constraint to profitable tomato production. Spider mites reduce the quality and quantity of tomatoes resulting in loss of income. The red form of the spider mites was more prevalent in farms across the country. All the farmers interviewed had prior knowledge of spider mites and their sources of pest information were personal experiences, agro-traders and fellow farmers. Demographic characteristics did not have a significant effect on the seriousness of the spider mite problem. The use of chemical pesticides was the most common method of controlling spider mites. An array of pesticides are applied, some of which are not in the list of chemicals recommended for spider mite control. Some farmers report reduced effectiveness of some of the pesticides used for its control. This has made its control very difficult since most farmers are resource poor and can not afford the cost associated with controlling spider mites. The second study evaluated the efficacy of abamectin, methomyl and vii chlorfenapyr against CSM eggs and adults in the laboratory. The treatments were each replicated three times. The toxic effect was evaluated in the laboratory bioassay after 24, 48, 72 and 96 h of application of pesticides. Chlorfenapyr and methomyl were highly effective in the control of eggs and adult spider mites. Although abamectin required longer exposure periods to achieve effective control of both eggs and adults it did not need to achieve high mortalities to offer adequate protection to the tomato crop. The study showed that the pesticides evaluated can be used as part of an integrated management programme to reduce resistance development by using one pesticide. The third study was conducted over two cropping seasons, 2018/2019 and 2019/2020, to evaluate the economic injury level and assess yield loss for carmine spider mite on tomato in Botswana. Tomato plants were infested with adult spider mites for periods of 0 (no exposure), 1, 2, 3, 4, 5, 6 and 7 weeks (complete exposure). The corresponding treatments were 7, 6, 5, 4, 3, 2, 1 and 0 sprays with abamectin. The results showed a significant reduction in the spider mite populations per plant as the frequency of spraying increased. An inverse relationship between spider mite exposure and yield was also observed following three weeks exposure. Yield loss increased to more than 50% when the pesticide was not applied to control spider mites. Economic decision levels are important components of cost saving integrated pest management programs and can be effective tools for making decisions about the application of pesticides against carmine spider mite in Botswana. The fourth study was conducted to establish pesticide metabolism enzymes activity among CSM strains collected from tomato fields in seven geographical locations of Botswana. Activities of metabolic enzymes, namely, esterases (α and β- esterases), cytochrome P450 monooxygenases and glutathione-S-transferases were estimated. The highest levels of α-esterase activity (nmol/min/mg of protein-1 ) were observed in the Bela-bela strain (1.966 nmol/min/mg of protein-1 ), followed by Sikwane (1.008nmol/min/mg of protein-1 ). The Sikwane strain (3.276 nmol/min/mg of protein-1 ) registered enhanced β-esterase activity, followed by the Glen Valley strain (1.966 nmol/min/mg of protein-1 ) and Francistown (1.102 nmol/min/mg of protein-1 ) strain. Elevated level of GSTs were observed in the Francistown (20.026 nmol/min/mg of protein-1 ), followed by the Moshupa (15.655 nmol/min/mg of protein-1 ) and Bela-bela (15.371 nmol/min/mg of protein-1 ) strains. The Francistown strain showed the highest (0.222 nmol/min/mg of protein-1 ) P450 monooxygenase activity followed by Bobonong (0.193 nmol/min/mg of protein-1 ) and Sikwane (0.135 nmol/min/mg of protein-1 ) strains. Variation in detoxification enzymes activity among CSM strains can be attributed to differing pesticide application regimes. These findings will be helpful in the selection of acaricides and in formulating resistance management strategies for effective management of spider mite in tomato fields in Botswana.
2023-07-01T00:00:00ZFactors influencing academic performance of pupils in the primary school leaving examination results for agriculture in Botswana
https://hdl.handle.net/13049/716
Factors influencing academic performance of pupils in the primary school leaving examination results for agriculture in Botswana
Jele, Lydia C.
The purpose of the study was to investigate the factors influencing performance of students in the primary school leaving examinations (PLSE) results for Agriculture in the Botswana. This national study targeted a total of 757 public primary schools in the country whereby a sample of 258 schools was obtained randomly from all primary schools in the Ministry of Education and Skills Development (MoESD). Out of a total of 416 participants from the 254 schools, 302 (73%) respondents returned the completed questionnaire which were mailed as an email attachment and also hand delivered by the researcher to gather data from teachers. The design of the study was descriptive and used a mixed methodology approach. A survey questionnaire was used to gather data through closed ended items and open-ended questions. Results found that, different factors influence the students’ performance in Agriculture in primary schools. The study also found that majority (59.3%) of the respondents in the study were female, 35.3% were within the age category of 41-50 years old, close to half (49.0%) of the teacher respondents in the study held the position designated as ‘teacher’ which is the entrance position in the teaching cadre in primary schools, majority of whom were in the lower level of positions or category of teaching than higher positions. The study recommended further training to upgrade teachers to a higher level to enhance their opportunities for promotions to higher positions in their teaching.
2023-05-01T00:00:00Z