Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.Sc. (Agriculture in Horticulture)) -- University of Limpopo, 2017. / Butternut squash (Cucurbita pepo) is highly susceptible to root-knot (Meloidogyne species) nematodes. Nemafric-BL and Nemarioc-AL phytonematicides were being researched and developed for use in various crop farming systems for managing nematode numbers. However, the two products when not properly quantified are highly phytotoxic to crops. The Curve-fitting Allelochemical Response Dosage (CARD) computer based model was adopted to compute the Mean Concentration Stimulation Point (MCSP), which is a non-phytotoxic concentration. The objective of the study, therefore, was to determine whether the MCSP values of Nemarioc-AL and Nemafric-BL phytonematicides on squash under greenhouse, microplot and field conditions exist. Seedling were raised in 25-cm plastic bags filled with loam, pasteurised sand and Hygromix 2:1:1 (v/v) in the greenhouse , raised in 25-cm pots with pasteurised sand and loam 3:1 (v/v) on the microplot, and raised under field with Hutton sandy loam (65% sand, 30% clay and 5% silt). After establishment each plant was inoculated with 5 000 eggs and second-stage juveniles (J2) of M. incognita. Treatments comprised 0, 2, 4, 8, 16 and 32% concentration of Nemarioc-AL and Nemafric-BL phytonematicides with ten replicates. For greenhouse, treatments comprised 0.0, 0.8, 1.6, 3.2, 6.4 and 12.8% concentration of both Nemarioc-AL and Nemafric-BL phytonematicide with 10 replicates. For micro-plot and for field experiment treatments comprised 2.4, 4.8, 9.6, 19.2 and 38.4% of both Nemarioc-AL and Nemafric-BL with nine replicates. In all experiments, treatments were arranged in a randomised complete block design with ten replicates. In the greenhouse, Nemafric-BL phytonematicide had highly significant effects on dry fruit mass and significant on fruit number, but had no effect other plant variables recorded. xxii Treatments contributed 51 to 71% in total treatment variation (TTV) of dry fruit mass and fruit number, respectively. However, at higher concentrations the same phytonematicide decreased fruit number by 66 to 137% and dry fruit mass by 6 to 14%. In the greenhouse, MCSP value for Nemafric-BL phytonematicide was 2.83% of which the overall Σk was 3 units. Plant variables and increasing concentration of phytonematicide exhibited quadratic relations. In microplot, Nemarioc-AL was highly significant for dry shoot mass and dry fruit mass with treatment contribution of 15 to 63% in TTV. At lower concentrations Nemarioc-AL phytonematicide increased dry shoot mass by 5%. However, with increasing concentrations dry shoot mass decreased from 7 to 30%. Phytonematicide increased dry shoot mass from 41 to 81% and decreased root galls from 3 to 73%. In microplot, MCSP value was 11.85%, with the Σk zero. Plant variables and increasing concentration of phytonematicide exhibited quadratic relations. In field experiment, Nemarioc-AL and Nemafric-BL phytonematicide treatment effect were not significant on any plant variables. In conclusion, the MCSP and Σk values appear to be location-specific since they were not similar in various locations.

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.A. Agriculture. (Plant Production)) -- University of Limpopo, 2021 / Root-knot (Meloidogyne species) nematodes are host to most plant species, with the success of most crops being dependent upon proper nematode management tactics. Sweet potato (Ipomoea batatas L.) is highly susceptible to root-knot nematodes, with physical damage being visible on roots. The withdrawal of highly effective fumigant synthetic nematicides from the agrochemical markets resulted in a need to investigate alternative strategies for managing high nematode population densities, with the use of nematode resistance being the most preferred strategy. The objectives of this study were (1) to establish whether sweet potato cv. 'Blesbok' would be resistant to M. javanica under greenhouse conditions, (2) to investigate whether cucurbitacin containing phytonematicides would be comparable to Velum synthetic nematicide in suppressing Meloidogyne species. For Objective 1, treatments comprised 0, 5, 25, 125, 625, 3125 and 15625 eggs and second-stage juveniles (J2), had six replications and validated in time. Uniform sweet potato cuttings were transplanted in 20-cm diameter plastic pots, filled with steam pasteurised (300°C for 1 hour) loam soil. At 56 days after inoculation, plant growth, plant nutrient and nematode variables were assessed using analysis of variance and subjected to lines of the best fit. Treatments had significant (P ≤ 0.05) effects on eggs and highly significant (P ≤ 0.01) effects on J2, final nematode population densities (Pf) and the reproductive factor (RF), contributing 39, 45, 42 and 92% in total treatment variation (TTV) of the respective variables. Treatments did not have significant effects on plant variables. Calcium, K, Mg and Fe versus M. javanica levels each exhibited negative quadratic relations, with the models being explained by associations from 59 to 96%. In contrast, Zn versus M. javanica levels exhibited positive quadratic relation, with the model being explained by 80 and 98% association and optimised at 125 M. javanica units. For Objective 2, four treatments, namely, untreated control, Nemarioc-AL phytonematicide, Nemafric-BL phytonematicide and Velum had 10 replications and also validated in time. The plantlets with well-developed root system were transplanted under field conditions. Data for Object 2 did not comply with the requirements for ANOVA and were therefore subjected to Principal Component Analysis (PCA). Nemafric-BL phytonematicide treatment in both experiments reduced eggs, J2 in roots and J2 in soil and RP of Meloidogyne species, with the results being comparable to those of Velum synthetic nematicide. Nemarioc-AL phytonematicide reduced J2 in roots and in soil of Meloidogyne species, without affecting eggs in roots and RP. Nemafric-BL phytonematicide and Velum each increased plant growth variables in Experiment 1 and Experiment 2, whereas Nemarioc-AL phytonematicide did not have significant effects on plant growth variables. Velum chemical nematicide stimulated the accumulation of most essential nutrient elements in leaf tissues of the test cultivar, followed by Nemafric-BL phytonematicide, whereas Nemarioc-AL phytonematicide had no significant effects on the accumulation of essential nutrient elements. The study had two major outcomes, namely, (1) that the efficacy of Nemafric-BL phytonematicide was comparable to that of Velum chemical nematicide in suppression of population densities of Meloidogyne species in cv. ′Blesbok′ under field conditions and (2) that cv. ′Blesbok′ was tolerant to M. javanica and therefore, it was not necessary to investigate the mechanisms of nematode resistance. / Agricultural Research Council (ARC) and National Research Foundation (NRF)

Thesis (M. Agric. (Plant Protection)) -- University of Limpopo, 2019 / Damage and significant losses of potato cultivar due to Meloidogyne incognita has become a serious challenge, after the withdrawal of synthetic chemical nematicides due to their environment-unfriendliness. Various alternatives have been investigated each with a wide range of drawbacks. Most phytonematicides were highly phytotoxic to crops, while their effects on nematode suppression were highly variable. The use of Nemarioc-AG phytonematicide at pre- and post-emergence would help in determining the level that is effective in supressing M. incognita without being phytotoxic. The objective of this study was to determine whether Nemarioc-AG phytonematicide could serve as pre- and post-emergent phytonematicide without inducing phytotoxicity while suppressing population densities of M. incognita. For achieving this objective, treatments, namely, 0, 2, 4, 8 and 16 g of Nemarioc-AG phytonematicide, were arranged in a randomised complete block design (RCBD), with 7 replicates. Potato seed tubers were sown into 20 cm pots, Nemarioc-AG phytonematicide placed above the tubers and covered with soil, after initiation of treatments 5 000 eggs and second stage juveniles (J2) of M. incognita per plant were inoculated. For post-emergent, treatments, replications and design were the same as in pre-emergent. Potato seed tubers were sown and inoculated with 5000 eggs and second-stage juveniles (J2) of M. incognita per plant after 100% emergence. Nemarioc-AG phytonematicide were applied 7 days after inoculation. Trials were conducted in autumn (February-April) 2017 (Experiment 1) and repeated in autumn 2018 (Experiment 2). Plant growth variables and selected nutrient elements were collected and analysed using the Curve Fitting Allelochemical Response Data (CARD) model and lines of best fit, respectively. In pre-emergent application, Experiment 1, MCSP was established at 1.95 g, with the overall xii sensitivity (∑k) being equal to zero. Therefore, in Experiment 1 and Experiment 2, all nutrient elements to increasing concentration of Nemarioc-AG phytonematicide exhibited negative quadratic relations. In both Experiments, nematode variables over increasing concentration of Nemarioc-AG phytonematicide on potato exhibited negative quadratic relations, except in Experiment 1, where J2 in roots exhibited positive quadratic relations, with models ranging between 72 to 99%. In post emergent, Experiment 1, MCSP was established at 1.57 g, with the overall sensitivity (∑k) being equal to 2. In Experiment 1 and Experiment 2, nutrient elements over increasing concentration of Nemarioc-AG phytonematicide exhibited positive and negative quadratic relations, with models ranging from 89 to 97%. In Experiment 1, nematode variables over increasing concentration of Nemarioc-AG phytonematicide exhibited negative quadratic relations, with models ranging between 92 and 98%. Positive and negative relations suggested that the product stimulated and inhibited plant growth or accumulation of selected essential nutrient elements, respectively. Increasing concentration of Nemarioc-AG phytonematicide had stimulated certain plant variables and inhibited population densities of M. incognita in pre- and post emergent application; therefore, this product was suitable for use as pre- and post emergent in management of nematodes on the test crop.

Thesis (M. Agric. (Plant Protection)) -- University of Limpopo, 2019 / Plant extracts exhibited broad spectrum of activities against root-knot (Meloidogyne species) nematodes and had long been considered as an attractive alternative due to their being biodegradable and posing limited risk hazards to the environment, animal and human health. Additionally, the materials had been dubbed as being of low-input costs and had been viewed as being easy to apply in agricultural systems. The objective of the current study was to investigate the efficacy of paint-brush flower (Kleinia longiflora) either as fermented or granular formulations on suppression of M. javanica and their related effects on growth of tomato (Solanum lycopersicum) plants under field and greenhouse conditions. Fermented crude extracts were applied at 0, 2, 4, 8, 16, 32 and 64%, whereas granular materials were applied at 0, 2, 4, 6, 8, 10 and 12 g. Regardless of the product, the treatments were arranged in randomised complete block design (RCBD), with 12 replications. Kleinia longiflora plants were collected from the wild, chopped into pieces, oven-dried at 52⁰C and fermented in effective microorganisms (EM) for 14 days, whereas the remained were retained for use as granular formulation. Tomato seedlings cv. ꞌFloradadeꞌ were used as test plants inoculated with 2500 eggs and second-stage juveniles (J2) of M. javanica. At 56 days after the treatments, nematode and plant variables were collected, prepared using appropriate methodologies and subjected to analysis of variance using Statistix 10.0 software to generate means. Plant variables were subjected to the Curve-fitting Allelochemical Response Data (CARD) computer-based model to generate appropriate biological indices. Nematode and mineral elements variable means were subjected to lines of the best fit. Findings showed second-stage juveniles (J2) in roots, J2 in soil, eggs and Pf under increasing concentration were highly significant and exhibited negative quadratic relationship. The model explained the associations by 82, xvii 81, 74 and 76%, respectively. In granular formulation, the product had no significant effects on nematode population densities. The fermented crude extracts significantly affected and exhibited positive quadratic relations for dry fruit mass, chlorophyll content, dry shoot mass, number of flowers, plant height, number of fruit and stem diameter of tomato plants. The model explained the relationship by 97, 94, 95, 96, 94, 97 and 96%, respectively. In contrast, in granular formulation, the product had significant effects and positive exhibited quadratic relations on Chlorophyll content under field and greenhouse, plant height, dry root mass and dry shoot mass. The model explained the relationships by 52, 45, 56, 47 and 59%, respectively. Plant variables and increasing concentration of the products exhibited density-dependent growth patterns for both formulations, with overall sensitivity (∑k) values of 1 and 11, respectively. In fermented liquid and granular formulations, the Mean Concentration Stimulation Point (MCSP) values were derived at 1.97% and 2.84 g, respectively. The increasing concentration of fermented K. longiflora also had significant effects and exhibited negative quadratic relations on the accumulation of K, Na and Zn in leaf tissues of tomato plants. The model explained the associations with 87, 94 and 94%, respectively. In conclusion, the findings in the current study suggested that the nematicidal chemicals in K. longiflora could not be released through irrigation water but could be released into solution through microbial degradation. Also, at low concentration suitable for use without inducing phytotoxicity, the products in either formulation could improve the accumulation of certain nutrients in leaf tissues of tomato plants.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21163号 / 農博第2289号 / 新制||農||1060(附属図書館) / 学位論文||H30||N5137(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 大澤 晃, 教授 北島 薫, 教授 神﨑 護 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21377号 / 農博第2301号 / 新制||農||1069(附属図書館) / 学位論文||H30||N5150(農学部図書室) / 京都大学大学院農学研究科農学専攻 / (主査)教授 奥本 裕, 教授 白岩 立彦, 教授 稲村 達也 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

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In this thesis, we study the unit root tests which includes the ADF, PP and KPSS tests, the long memory tests such as the R/S and GPH tests, and the applications of these methods in high frequency financial data analysis. The software SPLUS was adopted to analyze data and correction of the SPLUS program in unit tests are also proposed. To apply these two test methods in high frequency data, we quoted the library, HFlibrary designed by Yan and Zivot in 2003 for preliminary data analysis and propose a new library HFanalysis, which can be used in correcting high frequency data (excluding N.A. value, sorting transactions and retrieve a certain time of transactions), obtaining equi-distanced time intervals and testing for unit root and long memory properties. In additions, we apply this proposed library to simulate the power of traditional unit root methods such as the ADF test and long memory test method such as the R/S and to perform an empirical study. Finally, we explore the power of the ADF for testing data simulated from a threshold unit root model and simulate the percentiles of the null distribution of the following threshold unit root tests: WALD, LM, LR and W£f.