Gary Magadzire School of Agriculture, Engineering and Natural Sciences

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    Lime and Nitrogen Options on Maize (Zea mays L) Production In Sandy Textured Soils Of Masvingo, Zimbabwe
    (Great Zimbabwe University, 2022) Mdewa Steven
    Approximately, more than 70% of arable land in Masvingo Province, Zimbabwe has a surface soil pH of ≤ 5. There has been a linear decline in maize yields in the region over the last four decades, particularly on sandy textured acidic soils. The study explored the net interactive effect of dolomitic lime and ammonium nitrate fertiliser on growth and yield parameters of maize (Zea mays L) as well as their influence on soil pH. A Split plot design was used with 9 different treatment combinations of lime and nitrogen fertiliser coupled with three levels of lime (0, 1.5, and 3.0t ha-1L) against three levels of nitrogen fertiliser (0, 0.2, and 0.4t ha-1N). Yellow or Orange maize genotype of variety SC402 was established on two 612m2 plots, one site was a backup of the experimental plot. The field experimental trial spanned from the summer seasons of 2018/2019 to 2019/2020 on sandy textured soils classified as Fersiallitic Luvisols under irrigated conditions. The study was premised on three scientific theories namely, the Multiple limitation Hypothesis (MLH), the Law of the Minimum (LM) and the Law of Declining Yield Increments (LDYI). Growth and yield of maize is influenced by climatic, economic and soil factors. Soil acidity is largely caused by agronomic practices such as base uptake through crop harvests and application of fertilisers. Data was gathered over two seasons to evaluate and determine maize response to growth, yield and soil pH deviation for optimal lime and nitrogen application rates under irrigation conditions. Optimum lime and nitrogen application rates were realised as 3.0t ha-1and 0.2t ha-1N for growth, yield and soil pH parameter. There was an insignificant interactive effect of lime and nitrogen fertiliser treatment combinations on root depth. For belowground biomass index, there was p< 0.05 portraying a significant interaction at 95% confidence interval thus rejecting H0. Growth parameters of Leaf Area Index (LAI) and Plant Height (PH) were significant at p< 0.05 during the early growth period. The study concluded that maize growth and yield parameters are directly proportional to increase in both lime and nitrogen rates. With successive seasons of both lime and nitrogen application, cumulative residual effects of the two factors causes an average pH decline of ≤ 5 units annually
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    Contribution of Wildlife to Human Livelihoods and Economic Development in Communities Living Adjacent to Matusadona National Park, Zimbabwe
    (Great Zimbabwe University, 2023) Zvikonyaukwa Jesse
    In many African nations, wildlife has the potential to support livelihoods and economic development. Wildlife resources are crucial for enhancing human livelihood, reducing poverty, and increasing opportunities for rural and economic development. Contribution of wildlife resources towards economic development has been hindered by poor management caused mainly by humanwildlife conflicts. The study's objectives were to: (i) evaluate the influence of ecotourism to economic development of communities surrounding Matusadona National Park; (ii) assess the difficulties associated with managing wildlife resources in the Matusadona National park, (iii) explore economic developments offered by the use of wildlife resources in Matusadona National Park, and (iv) determine sustainable management practices which can be adopted to improve economic developments offered by the use of wildlife resources in Omay community. The study used questionnaires, interviews, focus group discussions, and secondary data sources to collect relevant information for the study. A sample of 140 participants was used with 100 (40%) randomly selected from a list of 250 households.According to the findings, 57% of participants were women. In Matusadona National Park, safari operations made up the majority (54.7%) of the ecotourism industry.The study results showed that most participants (80%) identified illegal killing of animal as a major challenge to the park authorities. The results also showed several benefits which were derived from the game park at household level but only one was supported officially. The benefit to community development from the game reserve were road works, with the majority of the participants from Negande (95%), Mahombekombe (64%) and Siakobvu (80%) acknowledging that activities in the game park contributed to road maintenance in their areas. Improvement of roads (51.4 %) was the only economic development which was supported equally from both methods of data collection. Majority of participants (59.3 %) indicated that construction of bridges was difficult and not supported by revenue from utilisation of wildlife resources. There is need to form community based natural resource management (CBNRM), involvement of local people and rural district council (RDC) in the decision making to improve economic development activities. It can be concluded that when sustainable management practices are adopted and put into practice, the use of wildlife resources can contribute more to economic development. It can be recommended that Matusadona National Park authorities must reconsider law enforcement strategies, engagement with local communities and increasing animal populations to boost tourism, resource utilisation and adopt sustainable management options for wildlife
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    Host-Plant Resistance Mechanisms (HPRs) of Commercial Sugarcane (Saccharum officinarum L.) Varieties in Response to Yellow Sugarcane Aphid (YSA) (Sipha flava Forbes) Herbivory under Irrigated Cropping Systems
    (Great Zimbabwe University, 2024) Sakadzo Nyasha
    Worldwide, the well-known and problematic Yellow Sugarcane Aphid (YSA) (Sipha flava) plagues sugarcane (Saccharum officinarum (L.). The study's objective was to classify and document commercial sugarcane accessions host-plant resistance mechanisms according to their morphology, physiology, phytochemistry, and biochemistry in response to YSA herbivory. First, a multidisciplinary systematic literature review (SLR) was conducted to comprehend the host plant resistance mechanisms (HPRs) of different sugarcane accessions in response to YSA herbivory. Second, seven sugarcane cultivars were subjected to factorial experiments utilizing a natural aphid infestation, with the following four objectives in mind; explore leaf pubescence that mediates resistance to YSA, assess physiological response as a tolerance mechanism to YSA herbivory, evaluate biochemical resistance in retort to YSA feeding, carryout phytochemical profiling of metabolites that confer resistance to YSA feeding, and reconnoiter plant resistant index (PRI) of tested sugarcane germplasm in response to YSA incursion. The results of the SLR revealed a bias towards S. flava in sugarcane, with most studies being skewed in favor of other crops, insect arthropods, and other aphid species. These results demonstrated the paucity of knowledge regarding the previously specified SLR objectives in sugarcane. The majority of the research focused on comprehending the host plant resistance mechanisms induced by sugarcane aphid (SCA). Therefore, studying YSA was novel and crucial for controlling this pest of sugarcane. The results of leaf pubescence (trichome density) varied significantly (p<0.05) among the sugarcane accessions in terms of leaf position and aphid number. Leaf pubescence resistance was ranked from high to low based on the trichome density: 00-1165 > ZN 8 > ZN 9 > ZN 3L > 96-1107 > N14 > ZN 10. Information on physiological tolerance was gathered using SPAD and CIRAS-3 instruments. The content of chlorophyll and the gas exchange responses of the sugarcane accessions under investigation showed significant (p<0.05) tolerance variations. In addition, the sugarcane accessions; 96-1107, N14, and ZN 10 were the most susceptible to the physiological damage caused by YSA. The findings showed that in susceptible sugarcane accessions, YSA decreased biochemical parameters (total protein, total soluble sugars, and total chlorophyll content). Furthermore, the evaluated biochemical properties of sugarcane accessions were either completely retained or partially decreased on resistant (00-1165) and moderately resistant (ZN 9, ZN 8, and ZN 3L) sugarcane accessions. The synthesis of high phenol and flavonoid content in sugarcane accessions was significantly (p<0.05) stimulated by YSA feeding. iv Additionally, there was a significant (p<0.05) positive correlation between the following: the percentage change in flavonoid content and the number of aphids, and the percentage change in phenol content. Three mechanisms of resistance; antixenosis, tolerance, and antibiosis were used to evaluate PRI. 00-1165 sugarcane accession is only moderately resistant, according to PRI reading of 37.6, when compared to other accessions that exhibit tolerance, antixenosis, and antibiosis traits. Furthermore, accessions such as ZN 8, ZN 3L, and ZN 9 have relatively >5 PRI in comparison to the susceptible check (ZN 10). Leaf pubescence and leaf position reduced YSA number among the sugarcane varieties. Among the sugarcane accessions, leaf pubescence and leaf position decreased the number of YSA. Additionally, in susceptible sugarcane accessions, YSA reduced the biochemical parameters that were examined. Furthermore, sensitive varieties' chlorophyll content and gas exchange responses were reduced by YSA, but tolerant varieties were able to maintain or compensate for these losses. Moreover, YSA increased the production of flavonoids and phenols in sugarcane accessions, resulting in induced resistance. The 00-1165 sugarcane accession exhibited a moderate expression of the three resistance mechanisms that were studied: tolerance, antibiosis, and antixenosis. Furthermore, antixenosis and tolerance resistance mechanisms were demonstrated by ZN 8, ZN 9, and ZN 3L. The susceptible accessions; N14, ZN 10, and 96-1107 PRI were unable to fall within the three resistance mechanisms. ZN 8 and ZN 9 sugarcane accessions showed low resistance to YSA stress, while 00-1165 exhibited medium resistance as shown by its aphid quantity ratio (AQR), which fell between 0.30-0.60. Moreover, low YSA sensitivity was observed in ZN 3L and 96-1107. N14 had a medium sensitivity as well. Finally, cultivar ZN 10 can be regarded as a very susceptible accession due to its AQR which was more than 1.50. For the Zimbabwean sugar sector, the SLR study on the previously described research objectives was required in order to incorporate resistance into the current Integrated YSA management tactics. Sugarcane growers should update their YSA management programs to include pubescent (high-density trichome) accessions. Growers of sugarcane should use biochemically tolerant YSA accessions in their crop management plans to maintain or compensate for total soluble sugars, according to the study's findings. The physiologically compensating and sustaining behavior of YSA tolerant accessions with respect to gas exchange responses and chlorophyll content should also be taken into consideration by farmers. Since seven sugarcane accessions were used, there is a need for ongoing screening of the industry's sugarcane germplasm for PRI based on antixenosis, v tolerance, and antibiosis. Molecular breeding approaches must be used to isolate the genes of high phenol and flavonoid tolerant varieties for YSA integrated management. As this study indicates, host plant resistance is a promising sustainable management option for controlling S. flava; thus, it needs to be incorporated into the current integrated pest management strategies (IPM) because there is an overreliance on chemical method.