Thesis (Ph. D.)--Oklahoma State University, 2005. / Vita. Includes bibliographical references (p.92-99).

Thesis (Ph. D. in engineering sciences)--Washington State University, December 2006. / Includes bibliographical references.

Lentil (Lens culinaris) is a major grain legume (pulse) crop in Canada. Ascochyta blight, caused by Ascochyta lentis Kaiser et aI. (1997) (syn. Ascochyta fabae Speg. f sp. lentis Gossen et aI., 1986) is an important disease of lentil in Canada and worldwide. This disease can be serious, especially in wet growing seasons, and losses can be as high as 70% due to reduction in yield and quality. The main objective of this study was to determine the mode of inheritance of resistance to seedborne ascochyta blight in lentil. Seven lentil cultivars/lines, four resistant (ILL 5588, Indianhead, PI 339283 and PI 374118 (tentative)) and three susceptible (Eston, Laird and ZT4), were crossed in all possible combinations, excluding reciprocals. Fl plants were grown in the greenhouse and spaced F2 plants were grown in an irrigated ascochyta nursery. F2 plants were harvested individually and seeds were plated on agar media to determine percentage seedborne ascochyta infection. F2 plants with [greater than or equal too] 12% seedborne ascochyta infection were considered resistant and those with > 12% seedborne ascochyta infection were considered susceptible. F3 rows were grown in an irrigated ascochyta nursery in the field and harvested in bulk. One hundred seeds from each of the F3 rows were plated on agar media and percentage seedborne ascochyta infection was determined. F3 families with [greater than or equal to] 12% seedborne ascochyta infection were considered resistant and those with > 12% seedborne ascochyta infection were considered susceptible. Chi-squared test of goodness-of-fit to various one and two gene ratios showed that the resistance in Indianhead lentil was governed by a single recessive gene. Resistance in ILL 5588 lentil was governed by a single dominant gene. The resistance in PI 339283 was governed by at least one dominant gene. Lentil line PI 374118 showed a high level of seedborne ascochyta infection and was regarded as susceptible. The recessive gene governing resistance in Indianhead lentil was epistatic to the dominant genes for resistance in ILL 5588 and PI 339283 lentil. Indianhead lentil showed high foliage infection by ascochyta, suggesting that resistance to seedborne ascochyta infection and resistance to foliage infection are controlled by two different genetic systems.

Gray leaf spot, induced by <I>Pyricularia grisea</I>, is a disease of increasing importance in tall fescue in the southeastern United States. Previous research has shown that several herbicides may predispose turfgrasses to some diseases and that certain essential nutrients may have antagonistic effects on fungal plant pathogens. The objectives of this research were to evaluate the effects of herbicide and nutrient treatments on gray leaf spot development in tall fescue. Inoculation techniques were also evaluated for establishing gray leaf spot on tall fescue in controlled environments. Field studies revealed that 2,4-D applications resulted in significantly higher quality turf and lower gray leaf spot incidence than the untreated control. Turf treated with 2,4-D amine + mecoprop + dicamba also exhibited significantly less foliar blight symptoms than the untreated control. In vitro experiments revealed the growth-inhibiting effects of 2,4-D on <I>P. grisea</I> implicated in the field, as mycelial growth was completely inhibited at concentrations of 500 and 1000 mg L^-1. Colony growth was not affected at 2,4-D concentrations up to 100 mg L^-1. Phosphorous acid treatments resulted in a reduction in turf quality compared to an untreated control, as did manganese and zinc treatments. Foliar blight caused by P. grisea was substantially increased in H₃PO₃-treated plots in 2003, where a 40% difference in blighted turf was observed between plots that received H₃PO₃ treatments every 14 days and the untreated control. Area under the disease progress curve (AUDPC) analysis also revealed the significant detrimental effects of the phosphorous acid treatments. No significant differences in disease incidence or leaf spot size among nutrient treatments were observed in greenhouse treatments. Isolate selection was a significant factor for disease development and leaf spot size following spray inoculation under optimal environmental conditions. In general, disease incidence increased as inoculum density increased. Placing plants in covered containers or plastic bags immediately following inoculation for a 24-h period also appeared to promote disease development. Seeding rate did not have a significant effect on gray leaf spot development. We conclude that herbicide applications do not predispose tall fescue to gray leaf spot development and that applications of nutrients alone do not suppress development of gray leaf spot in tall fescue. Adjusting cultural practices as additional control measures for gray leaf spot does not appear to be a successful approach to managing this increasingly important disease.

<I>Rhizoctonia</I> species are important pathogens of all turfgrasses, yet little is known about the structure of populations of these pathogens or the effect of disease control programs on population dynamics. Isolates of <I>Rhizoctonia</I> were obtained from a single creeping bentgrass putting green in 2002 and 2003 and from multiple tall fescue landscapes in 2003. Creeping bentgrass isolates were obtained by placing 5 mm soil cores on alkaline water agar, incubated at ~24 C for 1 to 2 days and the actively growing hyphae were transferred to potato dextrose agar (PDA). Tall fescue isolates were obtained from foliar lesions using the same procedures. Isolates were characterized using morphological characteristics, anastomosis reactions, nuclear staining, and ribosomal DNA (rDNA) sequences. From creeping bentgrass, 21 distinct clones of <I>R. solani</I> AG 2-2 IIIB were present in the sample population in 2002. Seven of these clones were also recovered on multiple sampling dates. Fifteen of the 21 clones from 2002 were recovered in 2003. All seven clones that were isolated in multiple sampling dates in 2002 were also recovered in 2003. There were 29 and 21 isolates of <I>R. zeae</I> collected from the sample population in 2002 and 2003, respectively. All 21 clones exhibited similar EC₅₀ values to mancozeb, chlorothanlonil and azoxystrobin. Of 224 isolates collected from tall fescue during 2003, 88 were <I>R. solani</I> AG 1, 105 were binucleate <I>Rhizoctonia</I> CAG 1, 14 were <I>R. zeae</I>, two were <I>R. cerealis</I>, and 15 were not identified to species or AG. One hundred and seventy four of the isolates were assayed for sensitivity to the fungicides flutalonil, iprodione, tebuconazole, and trifloxystrobin. Mean EC₅₀ values varied across fungicides and species, but generally were below 3.3 mg L^-1. The diversity of <I>Rhizoctonia</I> populations associated with tall fescue, and the range in fungicide sensitivities among species indicates that response to management programs may vary with location and environment. The effects of phosphorous acid on fungal growth, disease incidence and turfgrass quality was evaluated in vitro and in vivo. Mean EC₅₀ values of azoxystrobin (+SHAM) for <I>R. solani</I> 2-2 IIIB, and AG 1, <I>P. aphanidermatum</I>, and <I>R. zeae</I> were 1.27, 0.04, 0.012, and 0.145 mg L^-1, respectively. Applications of phosphorous acid to creeping bentgrass and tall fescue did not significantly reduce brown patch incidence or increase turfgrass quality in field or greenhouse experiments. The benefit of phosphorous acid as a fungicide or plant nutrient is questionable.

Random amplified polymorphic DNA (RAPD) markers were used in three genetic studies in lentil (<i>Lens culinaris</i> Medikus). The first study involved development of RAPD markers linked with genes for resistance to ascochyta blight, caused by <i>Ascochyta fabae</i> f. sp. lentis Gossen et al. Seventy F₂-derived F₃ (F_2:3) lines were field screened for ascochyta blight reaction in each of two hybrid populations, Indianhead x Eston and ILL 5588 x Eston, that were segregating for resistance to ascochyta blight. Resistance to ascochyta blight in ILL 5588 lentil was conferred by a single dominant gene (<i>Ral₁</i>), whereas resistance in Indianhead lentil was conferred by a single recessive gene (<i>ral₂</i>). An efficient DNA extraction procedure and a PCR protocol that yielded RAPD markers with high resolution were developed for lentil. Bulked segregant analysis was used to produce four bulks of DNA from resistant vs. susceptible F₂ plants in each of these two populations which were then screened for RAPD markers using 400 random oligonucleotide primers. One RAPD marker, UBC227₁₂₉₀, was linked to the recessive gene, <i>ral₂</i>, in Indianhead lentil in repulsion phase with a map distance of 14.1 ± 4.5 cM. No RAPD marker was linked with the <i>Ral₁</i> gene in ILL 5588 lentil. In the second study, RAPD markers were used to study phylogeny of the genus Lens. DNA, extracted from 23 accessions of all five taxa of the genus Lens (culinaris, orientalis, nigricans, odemensis and ervoides), was screened for RAPD polymorphisms, using 11 random oligonucleotide primers. Two accessions of the differentiated cytotype of L. nigricans were also included. One hundred and forty eight polymorphic RAPD markers were resolved. A dendrogram for these RAPD markers, using the unweighted pair group method, clearly separated all accessions into their supposedly related taxa. Lens orientalis was the undisputed progenitor of the cultivated lentil, <i>Lens culinaris</i>. A low level of RAPD polymorphism was observed in <i>Lens culinaris</i> and L. ervoides. The differentiated cytotype of L. nigricans was well separated from the normal cytotype of L. nigricans and was closely associated with the L. odemensis accessions, indicating its close genetic similarity to L. odemensis. Principal component analysis (PCA) also indicated a similar relationship among these accessions, but resulted in a better resolution of the groupings. In the third study, the genetic polymorphism of seven Canadian lentil cultivars were studied using RAPD markers. Four lentil cultivars, CDC Gold, CDC Matador, Eston and Indianhead each had a unique, cultivar-specific RAPD marker, allowing their identification.

<p>Ethiopian mustard (<i>Brassica carinata</i> A. Braun) or gomenzer is an oilseed crop that is well adapted to the highlands of Ethiopia. Evaluation of the local germplasm has resulted in the registration of high yielding cultivars, such as Dodolla and S-67. The oil of gomenzer contains about 40% erucic acid and the meal is high in glucosinolates. The objective of this research was to study the inheritance of erucic acid content in gomenzer and to introgress genes for the non2-propenyl glucosinolate trait from <i>B. napus</i> and <i>B. juncea</i>. The erucic acid content of F₁ seed from reciprocal crosses between the high erucic acid cultivars Dodolla and S-67 and zero erucic acid line C90-14 was intermediate between the parents indicating that erucic acid content in B. carinata was controlled by two nondominant genes with two alleles acting in an additive manner. Backcross F₁ seed derived from the backcross to the low erucic acid parent fell into three erucic acid classes with $<$0.5%, 6 to 16% and $>$16% erucic acid at the ratio of 1:2:1 indicating that erucic acid was under the control of two alleles each of at two loci. F₂ seed segregation data supported this observation. Each allele contributed approximately 10% erucic acid. The high glucosinolate B. carinata line C90-14, low glucosinolate <i>B. napus</i> cultivar Westar and <i>B. juncea</i> line J90-4253 were chosen as parents for the development of non2-propenyl glucosinolate <i>B. carinata</i>. The objective was to transfer genes for non2-propenyl glucosinolate content from <i>B. napus</i> and <i>B. juncea</i> into <i>B. carinata.</i> Interspecific crosses were made between <i>B. carinata</i> and <i>B. napus</i>, <i>B. carinata</i> and <i>B. juncea</i> and the interspecific F₁ generations were backcrossed to <i>B. carinata</i>. Backcross F₁ plants from the two interspecific crosses were intercrossed in an attempt to combine the two sources for non2-propenyl glucosinolate content in one genotype. Seed of backcross F₁ plants of the cropss ((<i>B. carinata</i> x <i>B. napus</i>) x <i>B. carinata</i>) contained a high concentration of 2-propenyl glucosinolate similar to those of <i>B. carinata</i>. Introgression of C genome chromosomes of <i>B. napus</i> into <i>B. carinata</i> was not effective in redirecting glucosinolate synthesis away from 2-propenyl and into 3-butenyl glucosinolate. This indicated that C genome chromosomes do not contain genetic factors for C3 $\to$ C4 glucosinolate precursor chain elongation, and that 2-propenyl glucosinolate synthesis is primarily controlled by genes on B genome chromosomes. Seed of ackcross F₂ plants of the cross ((<i>B. carinata</i> x <i>B. juncea</i>) x <i>B. carinata</i>) contained much reduced levels of 2-propenyl glucosinolate indicating that genetic factors for C3 $\to$ C4 glucosinolate precursor chain elongation were introgressed from the B genome of <i>B. juncea</i> into the B genome of <i>B. carinata</i>. However, a complete diversion of glucosinolate synthesis from 2-propenyl to 3-butenyl was not achieved. Further selections in segregating F₄ and F₅ generations of <i>B. juncea</i> derived <i>B. carinata</i> populations could yield the desired zero 2-propenyl glucosinolate B. carinata. The double interspecific cross was unsuccessful.

Dormancy characteristics and optimum conditions for germination of Cleome gynandra seeds have not been explained. Seed storage proteins were extracted, analysed with SDS-PAGE and sequenced. Seed proteins of Cleome were characterised by comparison with those of wild mustard (Brassica kaber). Wild mustard showed seed proteins composed of two α-chains of molecular weight (24-32 kDa) and another two β-chains of 18-22 kDa. The seed proteins of Cleome comprised two α-chain polypeptides of molecular weight (25-30 kDa), two β-chain polypeptides of molecular weight (18-20 kDa) and a smaller β-chain of 13-15 kDa. The storage proteins occurred in the seeds as dimeric complexes of molecular weight 40-65 kDa, which were broken into polypeptide chains of approximately 20 and 30 kDa by the reducing . action of DTT. Comparison with proteins in the proteome library and similarity index further confirmed that the seed proteins of Cleome had similarities with those of wild mustard. Two dimensional SDS-PAGE showed that the two species have nine similar polypeptides and four different ones. Events associated with dormancy release during seed germination still require explanation. Seeds of Cleome are characterised by low germination and there has been no explanation for this. Changes in protein expression during germination of Cleome in the presence or absence of light and at constant or alternating temperatures were examined. The germination of Cleome seeds at 20 degrees C was inhibited by light, but it was improved at 20 degrees C in darkness. There was no photoinhibition when seeds were germinated at constant 30 degrees C or alternating 20/30 degrees C (16 h night and 8 h day) for 10 days. Four proteins were observed to decrease in expression as germination progressed, but remained unchanged during photoinhibition. Photoinhibition was expressed more in seeds that were harvested late, after the pods had turned brown. These seeds showed a fifth, low molecular weight protein (13 kDa) that was absent from the immature seeds and embryos. Photinhibition is a pseudo-dormancy condition during which seed storage proteins are not utilised and the seed coat could partially play a role in it. The temperatures for the germination of Cleome in darkness have been determined. However, prior to this study the effects of temperature, light and pre-germination treatments (chilling, scarification, hydration and germination in the presence of KN0(3) or GA(3) on the germination of the seeds of this species have not been investigated. Seeds were germinated for 10 days and the final count of germination was used to determine seed performance. The highest germination percentage (60% and 80%, for a 2-year old and a l-year old seed lot, respectively) of untreated seeds was achieved when alternating temperatures of 20/30 degrees C (16 h/S h) in the dark or constant 30 degrees C in the dark were used. Among the pre-germination treatments, only scarification (puncturing of seeds at the radicle end) improved germination. Seeds were found to be negatively photoblastic, and the phenomenon was more pronounced when they were germinated at 20 degrees C and 12 h photoperiod or longer. Germination of photoinhibited seeds was, however, improved by treatment with GA(3) It is recommended that the germination of Cleome be undertaken under conditions of darkness and at either alternating 20/30 degrees C or continuous 30 degrees C. Seed lot vigour and seedling vigour are two important seed quality aspects that are used in defining the seed germination process. Seed germination is appropriately characterised by radicle protrusion and the attainment of normal seedling structures. However, the international rules for testing seeds combine radicle protrusion and normal seedling attainment in separating seed germination into the first and final counts. The challenge to a seed analyst testing the germination of a species whose first and final counts are unknown is that there is no statistical guideline to determine these important stages of seed germination. Cauliflower and broccoli, for which the first and final counts are published in the international rules for testing seeds and Cleome, for which there is no data on the first and final counts, were examined to determine the statistical significances of the first and final counts. Analysis of variance, logistic regression, 'broken-stick' regression models and survival analysis procedures were used. Analysis of variance showed that there were no differences between the germination percentages on the fourth, fifth and seventh days of germination. Low and stable standard deviations were recorded when evaluating germination after the fourth day. The germination curves of broccoli and cauliflower did not fit the Gompertz curve but fitted the exponential curve. The broken-stick model 'broke' the cumulative germination curve for the Cleome seed lots into two linear curves that were significantly different, but failed to break those for broccoli and cauliflower. However, this study confirmed the first and final counts for broccoli and cauliflower as determined by the international rules for testing seeds. Broken-stick modelling and life table analyses confirmed the fourth day as being appropriate to determine the first count for Cleome germination. There was no evidence of further seed germination after the seventh day as shown by probability density and hazard rate. It is suggested that for Cleome, the 'first count' and 'final count' be performed on the fourth and seventh day of the germination, respectively. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Submitted in fulfillment of the requirements of the Master of Technology Degree in Information Technology, Durban University of Technology, Durban, South Africa, 2014. / This dissertation reports on the original study that applies the differential evolution algorithm to support farmers with optimal strategic decision making in the crop planning system. The analysis and modelling of crop planning decision making process are attractive for producing formalized knowledge on cropping plans and choices of farmers under uncertainty. The formalization of the decision making process is generally becoming a crucial focal point for developing decision support systems that go beyond the limitation of formerly developed prescriptive approaches. This dissertation makes a distinctive contribution to the development of a formalized methodology to study the decision making process in crop farming systems. The research reported in this dissertation formulates crop-mix planning problems by concurrently maximizing net profit and crop production, while minimizing the total land in hectare used to determine optimal cropping patterns. Different optimal crop-mix problems formulated in this research were solved using a mathematical methodology of generalized differential evolution 3 algorithm to obtain globally optimal solutions. The methodology of this research strikes a balance between mathematical formulations of crop planning problems and effective implementation of crop planning decision models. Simulation experiments were conducted using the non-dominated sorted genetic algorithm II to validate the performance of the generalized differential evolution 3 algorithm for solving optimal crop planning problems. The empirical results of this study generally indicate that generalized differential evolution 3 algorithm is a viable alternative for optimal crop-mix planning decision. Based on the performance of the generalized differential evolution 3 algorithm, the design of a decision support system was realized which promises to assist farmers and decision-makers within the agricultural sector to make optimal decisions pertaining to crop planning.

Kelpak®, a seaweed concentrate (SWC) prepared from the brown seaweed Ecklonia maxima (Osbeck) Papenfuss, improves overall plant mass and fruit yield in a variety of crops. The main active principals isolated from Kelpak® are cytokinins and auxins. Although these compounds are partly responsible for the growth promoting effect observed with Kelpak® application, they do not fully account for the complete effect of Kelpak® treatment. For this reason the focus has turned to polyamines (PAs) which are found in all cells of plants, animals and microorganisms, including eukaryotic algae. Polyamines also have growth promoting effects in plants. A study was carried out to investigate the PA levels in E. maxima and Kelpak® through a biennial cycle and to investigate if the PAs present in Kelpak® may have an effect on root growth, alleviating nutrient deficiency and the transport and accumulation of PAs in plants. To determine the amount of PA in the stipes, fronds and SWC prepared from E. maxima, samples were collected monthly over a two-year period (June 2009-June 2011). Extracts were benzoylated and quantified using a Varian HPLC. Putrescine concentrations ranged from 15.98-54.46 μg.g⁻¹, 6.01-40.46 μg.g⁻¹ and 50.66-220.49 μg.g⁻¹ DW in the stipe, fronds and SWC, respectively. Spermine concentrations ranged from 1.02-35.44 μg.g⁻¹, 1.05-26.92 μg.g⁻¹ and 7.28-118.52 μg.g⁻¹ DW in the stipe, fronds and SWC, respectively. Spermidine concentrations fell below the detection threshold. This is the first report of PAs being detected in a SWC. The seasonal pattern established for the stipe, frond and SWC followed the same trend over a biennial cycle. Polyamines accumulated in the seaweed tissue during periods of active growth and as a stress response elicited by rough wave action. This PA trend was similar to the cytokinin trend reported by MOONEY and VAN STADEN (1984b) for Sargassum heterophyllum which suggests that PAs play an important role in the hormone cascade during active growth. Routine monthly screening of Kelpak® carried out in the Research Centre for Plant Growth and Development indicated that Kelpak® consistently resulted in more rooting in the mung bean bioassay than the IBA control. The potential root promoting effect of PAs were investigated. Individually applied PAs did not increase rooting in the mung bean bioassay, but a synergistic relationship was observed between Put (10⁻³ M) and IBA (10⁻⁴ M). When applied together, rooting increased significantly above Put (10⁻³ M) and IBA (10⁻⁴ M) applied separately. The Put-auxin combination produced a similar number of roots to those treated with Kelpak®. It is possible that the PAs present in Kelpak® have a synergistic effect with auxins present in Kelpak® to promote root development and growth. Several physiological effects of Kelpak® and PAs on plant growth were investigated in a series of pot trials. Kelpak® significantly improved the growth of P- and K-deficient okra seedlings and masked the detrimental effects exerted by P- and K-deficiency. The application of PAs (10⁻⁴ M) significantly improved the seedling vigour index (SVI) of okra seedlings subjected to N-deficiency. The statistical difference was attributed to the N-containing growth regulators and polyamines being degraded and metabolized by the okra seedlings. Polyamine application did not alleviate P- and K-deficiency but increased root growth significantly in seedlings receiving an adequate supply of nutrients. It is likely that the additional PAs supported auxin-mediated root growth. A pot trial with okra plants was conducted to establish if the PAs in Kelpak®, applied as a soil drench or foliar application, are absorbed and translocated in a plant. Plants were also treated with Put, Spm, Spd to establish if PAs can be absorbed and translocated. Once the fruit had matured, plants were harvested and the endogenous PA content quantified by HPLC in the roots, stems and fruits. Applying PAs as a soil drench was not as effective as a foliar spray at increasing the PA content in the different plant parts. Kelpak® treatment (0.4%) did not contribute more PAs in any plant part. Spermidine concentrations were higher, in the various plant parts, than Put or Spm, irrespective of the mode of application. The application of Put, Spd and Spm increased Spd concentrations in the roots. Considering that Spd is the main PA produced in the roots and that exogenously applied PAs are readily converted to Spd, it seems evident that Spd is the preferred PA for long-distance transport in plants. The cytokinins and auxins in Kelpak® play an important role in stimulating growth in plants. It is, however, the totality of different compounds in Kelpak® that gives it its unique growth stimulating ability. Polyamines, occurring within the seaweed contribute to this activity, having an active role in root production and thus increased plant growth. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.