Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 66-68).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1960. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: Darla J. Sherrier, Dept. of Plant and Soil Science. Includes bibliographical references.

M.Sc. (Nematology) / Please refer to full text to view abstract

Thesis (M.Sc. Agriculture (Agronomy) -- University of Limpopo, 2019 / Most sweet potato-producing regions in South Africa are heavily infested by the root knot (Meloidogyne species) nematodes, which are difficult to manage since the withdrawal of the highly effective fumigant synthetic chemical nematicides. Prior to the withdrawal, the management of Meloidogyne species was not a priority in sweet potato (Ipomoea batatas L.) production since methyl bromide was highly effective in suppressing nematodes. The withdrawal resulted in the introduction of various alternative nematode management strategies, with nematode resistance being the most preferred. However, progress in the use of nematode resistance had been hindered by limited information on accurate species identification since Meloidogyne species have a wide host range and some biological races. The objectives of the study were (1) to determine the degree of nematode resistance in sweet potato cv. 'Mafutha' to M. javanica, M. incognita races 2 and M. incognita race 4 and (2) to investigate the mechanism of resistance in sweet potato cv. 'Mafutha' to M. javanica, M. incognita race 2 and M. incognita race 4. A total of six Experiments were conducted. In each, treatments comprised 0, 25, 50, 125, 250, 625, 1250, 3125 and 5250 eggs and second-stage juveniles (J2), arranged in a randomised complete block design (RCBD), with six replications. Uniform rooted sweet potato cuttings were transplanted in 20-cm-diameter plastic pots filled with steam pasteurised (300˚C for 1 hour) loam soil and Hygromix-T mixed at 3:1 (v/v) ratio. At 56 days after inoculation, plant variables and nematodes in roots were collected. Meloidogyne javanica inoculum levels in Experiment 1 had highly significant (P ≤ 0.01) effects on dry shoot mass and, stem diameter, contributing 74% and 50% in total treatment variation (TTV) of the respective variables, whereas under M. incognita race 2 inoculum levels contributed 70% and 56% in TTV of dry root mass and dry shoot mass, respectively. Meloidogyne incognita race 4 inoculum levels contributed 65% xx and 58% in TTV of stem diameter and dry shoot mass, respectively. In Experiment 2, M. javanica treatment levels contributed 56% in TTV of dry root mass, whereas M. incognita race 2 inoculum levels had no significant effect on any plant variable. In contrast, M. incognita race 4 contributed 51% in TTV of vine length. In Experiment 1, the nematode levels had significant effects on reproductive potential (RP) values, with treatments contributing 96%, 86% and 76% in TTV of RP values in M. javanica, M. incognita race 2 and M. incognita race 4, respectively. In Experiment 2, treatments contributed 79%, 46% and 61% in TTV of RP values in the respective Meloidogyne species. Results of the study suggested that growth of sweet potato cv. 'Mafutha' was affected by nematode infection, whereas the test nematodes were able to reproduce and develop on the test potato cultivar. In conclusion, sweet potato cv. 'Mafutha' was susceptible to M. javanica, M. incognita race 2 and M. incognita race 4 and therefore, the cultivar should not be included in crop rotation programmes intended to manage tropical Meloidogyne species and races in Limpopo Province, South Africa. Since the cultivar was susceptible to the test nematodes, the study did not evaluate the mechanism of resistance. / Agricultural Research Council (ARC), National Research Foundation (NRF) and the Land Bank Chair of Agriculture

Thesis (M.Sc.(Plant Protection)) -- University of Limpopo, 2022 / Runner beans are extremely sensitive to root-knot (Meloidogyne species) nematodes. Phytonematicides had been consistently used in managing population densities of Meloidogyne species in various crops, with the application technologies being restricted to the ground leaching technology (GLT) and botinemagation technology, each with its own advantages and disadvantages. The use of seeds as carriers of active ingredients of phytonematicides and then drying prior to sowing, is being considered as another potential application strategy in seeds with hypogeal germination. In such seeds, during seedling emergence the seed cover and the endosperm remain below the soil surface, just above the developing root system. As a result, in phytonematicide-primed seeds, the seed structures could serve as carriers for the active ingredients of phytonematicides. In cucurbitacin phytonematicides, Nemarioc-AL and Nemafric-BL phytonematicides contain cucurbitacin A and B, respectively as active ingredients. The objectives of the study were two-fold, namely, to determine whether runner bean (Phaseolus coccineus L.) seeds would (1) serve as carriers of active ingredients of cucurbitacin-containing phytonematicides without affecting seed germination under in vitro conditions, (2) serve as carriers of cucurbitacins intended for suppression of M. incognita population densities under greenhouse and microplot conditions. Two separate studies were conducted under laboratory conditions, with seven treatment solutions at 0, 2, 4, 8, 16, 32 and 64% Nemafric-BL or Nemarioc-AL phytonematicide. After exposure to separate solutions for 2 h, runner bean seeds were dried on laboratory benches for 72 h. Treatments were arranged in a completely randomised design (CRD), with 8 replications. Two layers of filter papers were placed inside each Petri dish seeded with 10 primed and dried seeds. Petri dishes were incubated inside LABCON growth chamber at 25ºC and 75% relative humidity. Successful seed germination, viewed as emergence of radicle from the testa, was recorded daily for a period of 10 days, with each count being removed from Petri dish to avoid re-counting. Under greenhouse and microplot conditions, primed-and dried seeds were sown in plastic pots containing 2 700 ml steam-pasteurised sandy loam soil, arranged in a randomised complete block design, replicated six times and eight times, respectively. Each seedling was inoculated by distributing 5 000 eggs and second-stage juveniles (J2) of M. incognita race 4 using a 50 ml plastic syringe. Originally, pots were irrigated using 500 ml chlorine-free tapwater, which was reduced to half after seedling emergence at every other day. Plant variables were collected at 56 days after inoculation and data were subjected to the Curve-fitting Allelochemical Response Dose algorithm model. In vitro, germination percentage (R 2 = 0.96), radicle length (R 2 = 0.89) and plumule diameter (R 2 = 0.96) versus Nemarioc-AL phytonematicide exhibited positive quadratic relations. Similarly, the variables versus Nemafric-BL phytonematicide, exhibited positive quadratic relations. In vitro, Mean Concentration Stimulation Point (MCSP) value of Nemarioc-AL phytonematicide on runner bean seeds was 1.05%, whereas for Nemafric-BL phytonematicide MCSP value was 0.58%. Under greenhouse conditions, plant height (R 2 = 0.97), chlorophyll content (R 2 = 0.92), dry shoot mass (R 2 = 0.98), dead nodule number (R 2 = 0.90), total pod number (R 2 = 0.97) and active nodule number (R 2 = 0.93) versus Nemarioc-AL phytonematicide exhibited positive quadratic relations., Similarly, chlorophyll content (R 2 = 0.95), gall rating (R 2 = 0.82), dry shoot weight (R 2 = 0.69), stem diameter (R 2 = 0.85) and total nodule number (R 2 = 0.86) versus Nemafric-BL phytonematicide exhibited positive quadratic relations. Under greenhouse conditions, MCSP values for Nemarioc-AL and Nemafric-BL phytonematicides were 4.18 and 3.69%, respectively. Under microplot conditions, total number of nodules (R 2 = 0.88), number of nodules dead (R 2 = 0.99), number of nodules active (R 2 = 0.95), fresh root mass (R 2 = 0.99), and fresh pod mass (R 2 = 0.99) versus Nemarioc-AL phytonematicide, exhibited positive quadratic relations, whereas plant height (R 2 = 0.85), number of nodules dead (R 2 = 0.87), dry shoot mass (R 2 = 0.97), fresh root mass (R 2 = 0.97) and total number of nodules (R 2 = 0.63) versus Nemafric-BL phytonematicide exhibited positive quadratic relations. Under microplot conditions, MCSP values for Nemarioc-AL and Nemafric-BL phytonematicides were 3.76 and 3.93%, respectively, each with ∑k = 0. All degrees of Nemarioc-AL and Nemafric-BL phytonematicides profoundly reduced nematode numbers under greenhouse and microplot trials. Based on the information obtained from this study, it was confirmed that runner bean (P. coccineus) is sensitive to Nemafric-BL and Nemarioc-AL phytonematicides supported by the Curve-fitting Allelochemical Response Dose (CARD) model results due to most plant variables that had sensitivity values of zero. In conclusion, the priming technology should be developed further since it has the potential of being successful in nematode management in seeds with hypogeal germination / National Research Foundation (NRF) and Potatoes South Africa

Thesis (M.Sc. Agriculture (Plant Protection)) -- University of Limpopo, 2021 / In use of phytonematicides as an alternative to synthetic chemical nematicides, the major challenge had been the development of appropriate application technologies, which are currently limited to the ground leaching technology (GLT) and botinemagation (BNT) systems. The former is labour-intensive, whereas the latter requires infrastructure that could be costly for smallholder farmers. The priming of seeds with hypogenous germination properties in phytonematicide solutions could serve as an alternative method of the application of phytonematicides, where the cotyledons would serve as carriers of the active ingredients that are leached into the rhizosphere for suppression of nematode numbers. However, since germination is a chemical process, it is not known whether the active ingredients in cucurbitacin containing phytonematicides would interfere with germination and the subsequent emergence of the seedlings through the incidence of phytotoxicity as observed in the use of the products in crop production. The objectives of the study, therefore, were (1) to investigate the sensitivity and overall sensitivity of pea (Pisum sativum L.) plants to Nemarioc-AL and Nemafric-BL phytonematicides, and (2) to determine the mean concentration point (MCSP) for pea-inoculated with Meloidogyne incognita under greenhouse and microplot conditions, where seeds were previously primed in phytonematicide solutions. Two separate trials were conducted with seven treatments, namely, 0, 2, 4, 8, 16, 32 and 64% Nemarioc-AL or Nemafric-BL phytonematicide, arranged in completely randomised design (CRD), with 8 replications each. Pea seeds were primed in Nemarioc-AL and Nemafric-BL phytonematicide solutions for two hours and shade dried prior to sowing. In vitro trial, 10 seeds were spread uniformly on a moistened filter paper in sterilised petri-dishes with lids and placed in an incubator at 25oC. In vivo trials were under greenhouse and micro-plot conditions, pea seeds were sown in 25-cm and 30-cm diameter plastic pots, respectively. Pots were filled with pasteurised loam soil. Seedlings were inoculated with 5 000 eggs + second-stage juveniles (J2) of M. incognita. Treatments in each case included priming seeds as explained earlier, arranged in a randomised complete block design (RCBD), with 6 replications under greenhouse conditions and 8 replications under micro-plot conditions. In all cases, plant growth variables were assessed using the Curve-fitting Allelochemical Response Dose (CARD) model to generate biological indices which were used to calculate MCSP and the overall sensitivity (Σk). Nematode variables in inoculated trials were assessed using the regression model. In vitro trials, germination variables had positive quadratic relation versus Nemafric-BL phytonematicide, with MCSP= 0.62 % and ∑k = 34 units. In contrast, tested germination variables exhibited negative quadratic relations versus Nemarioc-AL phytonematicide. In greenhouse trials, MCSP values for Nemarioc-AL and Nemafric-BL phytonematicides were 0.62 and 2.18 %, respectively, with ∑k = 0. Plant height (R2 = 0.86), stem diameter (R2 = 0.93) and chlorophyll content (R2 = 0.85), exhibited positive quadratic relationship against Nemarioc-AL phytonematicide, whereas, plant height (R2 = 0.95), stem diameter (R2 = 0.92), chlorophyll content (R2 = 0.89), number of flowers (R2 = 0.93) and dry shoot mass (R2 = 0.94), exhibited positive quadratic relationship against Nemafric-BL phytonematicide. In micro-plot trials, MCSP values for Nemarioc-AL and Nemafric-BL phytonematicides were 0.71 and 2.45 %, respectively, with ∑k = 0. Plant height (R2 = 0.95), stem diameter (R2 = 0.98), chlorophyll content (R2 = 0.98), and gall ratings (R2 = 0.98), exhibited positive quadratic relationships against Nemarioc-AL phytonematicide, while chlorophyll content (R2 = 0.97) and gall ratings (R2 = 0.96) exhibited positive quadratic relationships against Nemafric-BL phytonematicide. All degrees of Nemarioc-AL and Nemafric-BL phytonematicides profoundly reduced nematode numbers under greenhouse and micro-plot trials. In conclusion, both Nemarioc-AL and Nemafric-BL phytonematicides could be applied through the priming technology on pea seeds which have hypogenous germination properties in suppression of nematode population densities. / National Research Foundation (NRF)

An investigation of the effect of Meloidogyne hapla, M. arenaria, M. arenaria thamesi, M. incognita acrita, and M. incognita on Ligustrum ovalifolium, L. japonicum, and Abelia floribunda was conducted. With the exception of M. hapla on L. ovalifolium and M. arenaria thamesi on A. floribunda, all 5 species of nematodes were pathogenic on the 3 host species. Striking differences in growth of the L. ovalifolium plants inoculated with the 4 root-knot species that caused significant reduction could easily be seen. Reduction in weight of the plants inoculated with the 4 root-knot species varied from 39.8% to 63.6% of the controls, and the reduction in total length of stems of these plants varied from 37.2% to 58.5% of the controls at the termination of the experiment. Reduction in weight of the L. japonicum plants inoculated with root-knot species varied from 29.2% to 51.7% of the controls. All plants inoculated with root-knot were significantly reduced in weight compared to controls. There were no visual differences in growth among the A. floribunda treatments; however, omitting the M. arenaria thamesi treatment which was not significantly different from control, the reduction in weight of the inoculated plants varied from 26.81 to 41.71 of the controls. / M.S.

Includes bibliographies. / xiv, 175, [96] leaves, [17] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis reports on the generation of molecular tools for the analysis of chromosome 6R of rye and the application of these tools in structural analysis of 6RL. Results presented include physical and genetic maps of chromosome 6RL incorporating RFLP and PCR markers and CreR, the locus conferring resistance to cereal cyst nematode (CCN). The ability to detect small introgessions of rye chromatin in wheat is demonstrated. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1997

Bibliography: leaves 133-152 / iv, 152 leaves, [47] leaves of plates : ill. (1 col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1987