京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21604号 / 理博第4511号 / 新制||理||1647(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)准教授 中野 隆文, 教授 曽田 貞滋, 教授 中務 真人 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

In this study, surveys were conducted in pea and potato fields in North Dakota and Central Minnesota to investigate the incidence and abundance of plant-parasitic nematodes in these fields. Moreover, the effect of the pin nematode, Paratylenchus nanus, on plant growth and yield of six field pea cultivars was determined under greenhouse conditions. Similarly, the influence of lesion nematode, Pratylenchus penetrans, and wilt fungi, Fusarium oxysporum alone and together on growth and yield of potato cultivar ‘Red Norland’, was evaluated in microplots under field conditions. The results indicate Paratylenchus spp. and Pratylenchus spp. are the most frequent nematodes, respectively, in pea and potato fields. Pin nematodes reproduced on field pea cultivars and caused up to 37% reduction in plant height and 40% reduction in yield. Additionally, both P. penetrans and F. oxysporum alone, and together had significant negative effect on growth and yield of potato.

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. Agriculture (Horticulture)) -- University of Limpopo, 2019 / Cucurbitacin-containing phytonematicides and a variety of unidentified soil microbes in suppressive soils (Biomuti) had been consistent in suppression of population densities of root-knot (Meloidogyne spp.) nematodes on various crops. However, information on suppressive effects of cucurbitacin-containing phytonematicides and Biomuti on citrus growth and suppression of the citrus nematode (Tylenchulus semipenetrans) had not been documented. The objective of this study therefore, was to determine the interactive effects of Nemarioc-AL and Nemafric-BL phytonematicides and Biomuti on growth and nutrient elements in leaf tissues of Poncirus trifoliata rootstock seedlings under greenhouse and field conditions. Uniform six-month-old citrus rootstock seedlings [Du Roi Nursery (Portion 21, Junction Farm, Letsitele)] were transplanted in 4 L plastic bags filled with growing mixture comprising steam-pasteurised (300°C for 1 h) loam and compost (cattle manure, chicken manure, sawdust, grass, woodchips and effective microorganisms) at 4:1 (v/v) ratio and placed on greenhouse benches. A 2 × 2 × 2 factorial experiment with the first, second and third factors being Nemarioc-AL phytonematicide (A) and Nemafric-BL phytonematicide (B) and Biomuti (M), were arranged in randomized complete block design, with 10 blocks. The treatment combinations were A0B0M0, A1B0M0, A0B1M0, A0B0M1, A1B1M0, A1B0M1, A0B1M1 and A1B1M1, with 1 and 0 signifying with and without the indicated factor. Treatments were applied at 3% dilution for each product as substitute to irrigation at a 17-day application interval. Under greenhouse conditions, seedlings were irrigated every other day with 300 ml chlorine-free tap water. Under field conditions, the study was executed using similar procedures to those in the greenhouse trial, except that the citrus seedlings were transplanted directly into the soil of a prepared field and seedlings were irrigated using drip irrigation for 2 h every xxi other day. At 64 days after transplanting, plant growth variables were measured and foliar nutrient elements were quantified using the Inductively Coupled Plasma Optical Emission Spectrometry (ICPE-9000). Data were subjected to analysis of variance using SAS software. Significant second and first order interactions were further expressed using the three-way and two-way tables, respectively. At 64 days after the treatments, under greenhouse conditions Nemarioc-AL × Nemafric-BL × Biomuti interaction was not significant (P ≤ 0.05) on plant variables of seedling rootstocks in both experiments. In contrast, the Nemarioc-AL × Biomuti interaction was highly significant (P ≤ 0.01) on stem diameter, contributing 52% in TTV of the variable in Experiment 1 (Table 3.1), whereas in Experiment 2 the interaction was highly significant on dry shoot mass, contributing 33% in TTV of the variable (Table 3.2). Relative to untreated control, the two-way matrix showed that the Nemarioc-AL × Biomuti interaction, Nemarioc-AL phytonematicide and Biomuti each increased stem diameter by 1%, 12% and 5%, respectively (Table 3.3). Relative to untreated control, the two-way matrix table showed that Nemarioc-AL × Biomuti interaction increased dry shoot mass by 10%, whereas Nemarioc-AL phytonematicide and Biomuti each increased dry shoot mass by 23% and 17%, respectively (Table 3.4). Nemarioc-AL × Nemafric-BL × Biomuti interaction was not significant (P ≤ 0.05) for all plant growth variables in both experiments. However, Nemarioc-AL × Nemafric-BL interaction was significant for leaf number and stem diameter contributing 45% and 29% in TTV of the respective variables in Experiment 2 (Table 4.1). Relative to untreated control, two way matrix table showed that the Nemarioc-AL × Nemafric-BL interaction and Nemafric-BL phytonematicides each increased stem diameter by 8% and 11% respectively, whereas Nemarioc-AL phytonematicides reduced stem diameter by 2% (Table 4.2). Also using two-way matrix table showed that Nemarioc-AL and Nemafric xxii BL phytonematicides each increased leaf number by 1% and 7% respectively, whereas the Nemarioc-AL × Nemafric-BL interaction increased leaf number by 6% (Table 4.2). Nemafric-BL × Biomuti interaction was significant for stem diameter contributing 29% in TTV of the respective variable in Experiment 2 (Table 4.1). Using two-way matrix table showed that Nemafric-BL × Biomuti interaction and Nemafric-BL phytonematicide each increased stem diameter by 7%, whereas Biomuti alone reduced stem diameter by 6% (Table 4.3). Under greenhouse conditions, the second order Nemarioc-AL × Nemafric-BL × Biomuti interaction was highly significant for foliar Mg, contributing 5% in TTV of the variable in Experiment 1 (Table 3.4). Relative to untreated control, the three-way matrix table showed that the three factors, Nemafric BL phytonematicide and Biomuti each reduced Mg by 33%, 35% and 53%, respectively, whereas Nemarioc-AL phytonematicide increased Mg by 12% (Table 3.5). Nemarioc-AL × Biomuti interaction was highly significant for foliar Mg, contributing 9% in TTV of the variable in Experiment 1 (Table 3.4). Relative to untreated control, the two-way matrix table showed that the Nemarioc-AL × Biomuti interaction and Nemafric-BL phytonematicide reduced Mg by 42% and 12%, respectively, whereas Nemarioc-AL phytonematicide alone increased Mg by 14% (Table 3.6). Nemarioc-AL × Biomuti interaction was highly significant for foliar Ca and Mg, contributing 59 and 4% in TTV of the respective variables in Experiment 1 (Table 3.4). Also using two-way matrix table showed that Nemarioc-AL phytonematicide and Biomuti separately reduced Ca by 12% and 22% respectively, whereas the Nemarioc-AL × Biomuti interaction increased Ca by 1% (Table 3.7). Relative to untreated control, the Nemarioc-AL × Biomuti interaction, Nemarioc-AL phytonematicide and Biomuti reduced foliar Mg by 26%, 21% and 33%, respectively (Table 3.7). Nemafric-BL × Biomuti interaction was highly significant for foliar Mg and P, contributing 50 and 21% xxiii in Experiment 1, whereas in Experiment 2 the interaction was significant for foliar Ca and Mg, contributing 41% and 38% in TTV of the respective variables (Table 3.4). Relative to untreated control, the two-way matrix table showed that Nemafric-BL phytonematicide and Biomuti individually reduced Mg by 60% and 51%, respectively, whereas the Nemafric-BL × Biomuti interaction reduced Mg by 38% (Table 3.8). Also, in the two-way matrix table the Nemafric-BL × Biomuti interaction and Nemafric-BL phytonematicide each reduced Mg by 13% and 2%, respectively, whereas Biomuti alone increased P by 17% (Table 3.8). Relative to untreated control, Nemafric-BL phytonematicide and Biomuti reduced Ca by 29% and 18%, respectively, whereas Nemafric-BL × Biomuti interaction reduced Ca by 14% (Table 3.9). Using two-way matrix table showed that Nemafric-BL phytonematicide and Biomuti separately reduced Mg by 21%, whereas the Nemafric-BL × Biomuti interaction reduced Mg by 16% (Table 3.9). Interaction of Nemarioc-AL × Nemafric-BL × Biomuti had no significant effect on K, Na and Zn in both experiments. Under field conditions, the second order Nemarioc-AL × Nemafric-BL × Biomuti interaction was not significant for all the nutrient elements in Experiment 1. Nemarioc-AL × Biomuti was significant for Ca, K and highly significant for Mg and P, contributing 31, 8, 23 and 19% in TTV of the respective variables in Experiment 1 (Table 4.4). Relative to untreated control, two-way matrix table showed that Nemarioc-AL phytonematicide and Biomuti each increased Ca by 15% and 26% repectiviely, whereas the Nemarioc-AL × Biomuti increased Ca by 17% (Table 4.5). Interaction of Nemarioc-AL × Biomuti, Nemarioc-AL phytonematicide and Biomuti each reduced Mg by 48%, 70% and 37% (Table 4.5). Also using two-way matrix table showed that Nemarioc-AL phytonematicide and Biomuti each increased P by 4% and 5% respectively, whereas the Nemarioc-AL × Biomuti interaction increased P by 50% (Table 4.5). Realative to untreated control, xxiv Biomuti and Nemarioc-AL phytonematicide each reduced K by 10% and 5% respectively, whereas the Nemarioc-AL × Nemafric-BL interaction reduced K by 38% (Table 4.7). Nemafric-BL × Biomuti interaction was highly significant for Mg and Zn, contributing 11% and 29% in TTV of the respective variables in Experiment 1 (Table 4.4). Relative to untreated control, two-way matrix table showed that Nemarioc-AL phytonematicide and Biomuti separately increased Mg by 1% and 19% respectiviely, whereas the Nemafric-BL × Biomuti interaction reduced Mg by 43% (Table 4.6). Nemafric-BL × Biomuti interaction, Nemafric-BL phytonematicide and Biomuti each reduced Zn by 35%, 31% and 64% (Table 4.6). Using three-way matrix table showed that the Nemarioc-AL × Nemafric-BL × Biomuti, Nemarioc-AL × Nemafric-BL, Nemarioc-AL × Biomuti and Nemafric-BL × Biomuti interactions each increased Ca by 44%, 18%,10% and 24% (Table 4.8). Further the matrix showed that Nemarioc-AL, Nemafric-BL phytonematicides and Biomuti each increased Ca by 25%, 31% and 23% (Table 4.8). Under both greenhouse and field conditions, although second and first order interactions were not consistent of various variables, results demonstrated that the three products interacted significantly for various products. In conclusion, the study suggested that these innovative products could be used in combination with Biomuti to stimulate plant growth but had antagonistic effects on accumulation of nutrient elements in P. trifoliata rootstock seedlings, suggesting that the products should be applied separately. / Agricultural Research Council-Universities Collaboration Centre and the National Research Foundation (NRF)

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 (Ph.D. Agriculture (Plant Production)) -- University of Limpopo, 2020 / Worldwide, both root-knot (Meloidogyne species) and sugarcane aphid (Melanaphis sacchari Zehntner), are economic pests on sugarcane and sorghum crops. In most cases, each of the two pests is managed using host plant resistance due to the economic benefits derived from this management strategy. The highly nematode resistant sweet stem sorghum (Sorghum bicolor L.) cv. 'Ndendane-X1' used in ethanol production, is highly sensitive to sugarcane aphid, with some indication that the latter could interfere with nematode resistance in the sorghum cultivar. This study had four objectives which collectively intended to investigate the interactive effects of infection by three Meloidogyne species and infestation by aphid under different conditions on resistance to nematode in a nematode-resistant sorghum cultivar. The research objectives were achieved through four trials. In each trial a 2 × 2 factorial experiment, each with and without nematode and aphid as first and second factors, respectively, were conducted. Treatments were arranged in a randomised complete block design, with six replications, and each experiment validated in time. At 150 days, after emergence, the nematode × aphid interaction significantly reduced sucrose by 17, 74 and 42% in Meloidogyne enterolobii, Meloidogyne incognita and Meloidogyne javanica trials, respectively. Aphid infestation of sorghum significantly increased the reproductive potentials of the three respective Meloidogyne species by 196, 320 and 152%, but significantly, reduced plant growth variables from 20-44 and 48-51% in two respective trials. The mineral nutrients S and Zn were reduced in leaf tissues of the test cultivar in Trial 1, whereas Ca and Zn were respectively reduced by 24 and 51% in Trial 2 and by 52 and 51% in Trial 3. Since the reproductive potential values for Meloidogynqe species on the test sorghum cultivar were greater than unity and nematode infection reduced the plant variables, cv. 'Ndendane-X1' lost resistance to xx the test Meloidogyne species. In achieving Objective 2, procedures were similar to those in Objective 1 except that the study was conducted under field conditions under mixed nematode populations of M. enterolobii, M. incognita and M. javanica. Sorghum seedlings were raised at 0.3 m × 0.3 m inter and intra row spacings. Soon after emergence, plants were thinned to one per station, randomly selected for nematode and nematode-aphid treatments. Mixed populations of Meloidogyne species (M. enterolobii, M. incognita and M. javanica) at approximately 1:1:1 (v/v) ratio were applied at 300 eggs + J2 per plants after thinning at the five plants which were used as nematode alone treatments. The latter were also infested with 20 sugarcane aphids to constitute a nematode + aphid treatments. Buffer zone plants separating the treatments were monitored for aphids and stock borer, which were sprayed when necessary. At 150 days after infestation, relative to nematode alone, nematode-aphid significantly reduced degrees Brix from 13% to 61%, but significantly increased the reproductive potential of mixed Meloidogyne species and root galls by 279 and 199%, respectively. Also, the combined effect significantly reduced plant growth variables from 35 to 55% and the mineral nutrient elements in leaf tissues of the cultivar from 33 to 73%. At 150 days after the treatment, the second and first order interaction (Nemarioc-AL × Nemafric-BL × Mordica and Nemafric-BL × Mordica) had significantly increased sucrose content from 48 to 66%, increased plant growth variables from 49 to 163%, increased accumulation of certain nutrient elements from 164 to 206%. The terpenoid-containing phytonematicides could have potential future application in the husbandry of ethanol-producing sweet stem sorghum cultivars in relation to increasing sucrose above the 16% minimum for premium delivery fees and increased plant growth. Under field conditions, in pest-free condition (Objective 3), drenched terpenoid-containing phytonematicides significantly increased sucrose content at xxi middle and bottom part of SSS cv. 'Ndendane-X1' by 66 and 48%. However, these products did not significantly increase plant variables, except tiller number, which was increased by 163 under first order interaction from Nemafric-BL and Mordica phytonematicides. Similarly, nutrient elements variables had generally not been increased by the interaction of these products, except Ca and K, which were increased by 206 and 164%. In achieving Objective 4, a 2 × 2 × 2, with the first, second and third factor being Nemarioc-AL (with and without), Nemafric-BL (with and without) and Mordica (with and without) phytonematicides, respectively. on sorghum cultivar infected with a mixture of Meloidogyne species and infested with aphids, under microplot conditions, untreated control sucrose content remained below the standard of 16 degrees Brix, whereas the second order interaction increased the variable far above the standard, along with various plant growth variables also increased. However, both nematode and aphid population densities were significantly reduced by the interactions. Findings in this thesis constituted the first report where aphid infestation broke resistance to Meloidogyne species in sweet stem sorghum cv. 'Ndendane-X1'. Therefore, the successful use of nematode resistance in the cultivar in areas with high nematode population densities would depend upon the effective management of the sugarcane aphid population densities. Also, the three terpenoid-containing phytonematicides would when combined or used alone have the potential future in the husbandry of sweet stem sorghum cultivars intended for ethanol production and suppression of nematode population densities / National Research Foundation (NRF)

No description available.

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.

Fine structural analyses of host tissue (alfalfa, Medicago sativa L.) response to infection by the stem nematode (Ditylenchus dipsaci Kühn) were conducted. Hypocotyl regions were taken on 1,3 and 7 days after inoculation. Electron micrographs of infected tissue indicated the types of damage were the same between Lahontan (tolerant line) and Ranger (susceptible line). Only the infection rate (in percent) and degree of damage were different between lines and among the different temperatures (15, 20 and 25 C). The higher the temperature, the more injury resulted. After 3 to 7 days of infection, the symptoms observed were swelling and broken endoplasmic reticulum (ER), distended and broken chloroplasts, loss of nuclear material and bulging and rupturing of nuclear envelopes. Heavily infected cell walls showed more osmiophilic substances on one side. Infected cytoplasm contained more ER (both rough and smoothER), ribosomes, vesicles and Golgi apparatus, suggesting increased metabolic activities. Lobing nuclei were observed in all treatments. Lipid content varied with temperature in one-day-old seedlings. At 15 and 25 C, electron dense substances were commonly found along the tonplast, intercellular spaces and on the cell wall. Also some enlarged ER were noted in the non-infected controls at these temperatures. From the fine structural studies of host tissue it is not possible at this time to determine the nature of resistance of alfalfa lines to nematode infection. More studies at both the biochemical and electron microscopical levels are needed. Further, studies on the activities of the nematodes at the various temperatures during the infection periods would be primarily important.

No description available.