Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: In South Africa, canola (Brassica napus L.) is produced under short day conditions during winter months. These conditions, together with high fertiliser application levels required to maximize grain yields, often result in tall growing bulky crops which are prone to lodging. This will especially be true if canola production is expanded to irrigated areas. Plant growth regulators (PGRs) have successfully been used to reduce canola plant height and lodging under experimental conditions in Australia and are worldwide commercially used to reduce plant height and lodging in winter cereals such as wheat and barley. The primary objective of this study was to determine the effect of anti-lodging PGRs on the agronomic and quality characteristics of commercial canola cultivars under South African conditions. This study was conducted under field conditions at three research farms, as well as controlled glasshouse conditions at Welgevallen Research Farm, situated in the Western Cape Province of South Africa. Foliar treatments consisted of a control (untreated) and four PGRs; CeCeCe® 750 (chlormequat chloride), Moddus® 250 EC (trinexapac-ethyl), Primo MAXX® (trinexapac-ethyl), and Kelpak®, applied either individually or in combination with wetting agent at budding stage (growth stage 3.1) of canola. Whilst glasshouse trials were conducted with spring canola cultivars “Hyola 555TT” and “43C80”, field trials were done with Hyola 555TT only. Monitoring and measuring various plant parameters during different growth stages of canola, the morphological and physiological impact of PGR-treatments on growth and development were determined. Though Primo MAXX® tends to reduce plant height in all trials; reductions were only significant during one of the glasshouse trials. Fortunately, compared to the control, none of the PGRs significantly reduced the leaf area, number of flowers or number of pods plant-1 during this study, while Primo MAXX® and Moddus® 250 EC tend to increase the grain yield under field conditions. This study indicates that PGRs can possibly be used to improve lodging resistance and yield of canola. Identifying the most effective PGRs on specific cultivars, the results of the study will contribute to the knowledge of using PGRs in canola to reduce lodging and improve grain yields in South Africa. / AFRIKAANSE OPSOMMING: In Suid-Afrika word canola (Brassica napus L) gedurende die wintermaande onder kort-dagtoestande verbou. Hierdie verbouingstoestande, tesame met verhoogde toediening van bemesting vir maksimum opbrengs, lei dikwels tot welige, hooggroeiende plantegroei, wat „n geneigdheid toon om om te val (lodge). Hierdie probleem vererger indien canola onder besproeiingstoestande gekweek sou word. Plantgroeireguleerders (PGRs) is reeds met sukses onder eksperimentele toestande in Australië gebruik om die planthoogte en dus omval (lodging) van canola te beperk. Plantgroeireguleerders word reeds kommersieel gebruik om planthoogte en omval van wintergraangewasse, soos koring en gars te verminder. Die hoofdoel van hierdie studie was om die effek van omval-teenwerkende PGRs op die agronomiese en kwaliteitseienskappe van kommersiële canola-kultivars onder Suid-Afrikaanse groeitoestande te bepaal. Hierdie studie is uitgevoer d.m.v. veldproewe op drie navorsingsplase, sowel as gekontrolleerde glashuisproewe te Welgevallen Navorsingsplaas, geleë in die Wes-Kaapprovinsie van Suid-Afrika. Blaartoedienings het bestaan uit „n kontrole (onbehandeld) en vier PGRs: CeCeCe® 750 (chlormequat chloride), Moddus® 250 EC (trinexapac-ethyl), Primo MAXX® (trinexapac-ethyl) en Kelpak®, wat afsonderlik of in kombinasie met benattingsmiddels toegedien is tydens die blomknopverskyningstadium (groeistadium 3.1) van canola. Die glashuisproewe is uitgevoer met lente-canolakultivars, nl. “Hyola 555TT” en “43C80”, terwyl veldproewe slegs uitgevoer is met Hyola 555TT. Verskeie plantparameters is gemonitor en gemeet gedurende die verskillende groeistadia van canola, waartydens en die morfologiese en fisiologiese impak van PGR-toedienings op die groei- en ontwikkeling van canola bepaal is. Alhoewel Primo MAXX® neig om die planthoogte in al die proewe te verkort, het dit planthoogte slegs beduidend verkort in een van die glashuisproewe. Geen van die PGRs het in vergelyking met die kontrole, die blaar-oppervlakte, aantal blomme of aantal peule plant-1 beduidend verminder gedurende die studie. Primo MAXX® en Moddus® 250 EC het inteendeel daartoe geneig om die saadopbrengs onder veldtoestande te verhoog. Hierdie studie toon dus dat PGRs moontlik gebruik kan word om omval te verminder en die opbrengs van canola te verhoog. Deur die mees doeltreffendste PGRs op spesifieke kultivars te identifiseer, kan die resultate van hierdie studie bydra tot die kennis van die gebruik van PGRs op canola, om omval te voorkom en saadopbrengs in Suid-Afrika te verhoog.

A strategy for the discovery of new insect growth regulators from arid lands plants was developed. Plant genera with a history of toxicity, medicinal use, or incorporation in native american cultures were selected. Forty-five species from twenty-one families were collected, extracted, and tested for biological activity on the large milkweed bug, Oncopeltus fasciatus. Eight extracts were toxic and the extract of Nama hispidum (Hydrophyllaceae) caused nymphs to undergo precocious metamorphosis to an adult. The active component of N. hispidum was precocene II (6,7-dimethoxy-2,2-dimethyl chromene). Nine Nama species, representing four of the five sections in the genus were gathered from Hawaii, California, Nevada, Arizona, New Mexico, and the Dominican Republic. In addition to the insect anti-hormone, precocene II (PII), present in N. hispidum, N. rothrockii contained at least two different insect juvenile hormone mimics, and N. sandwicense contained insect anti-hormone and insect juvenile hormone mimics. Fifth instar larvae of Heliothis zea were used as model insects to distinguish between post-ingestive intoxication and feeding deterrency during exposure to PII. Larvae fed artificial diet with PII were deterred from eating, and had retarded weight gain, growth, and development. Insects grown on diet with PII consumed less food, could not digest the food, or convert ingested food to body mass. in vivo radiotracer studies with the nutrient, ¹⁴C linoleic acid, show a lower rate of transport and incorporation of radioactivity into fat body tissue. A change in the midgut epithelial cells from PII resulted in reduced transport efficiency and retarded larval growth and development. Scanning electron microscopy of the midgut epithelia indicated that cytotoxic damage is induced by PII. Observed changes in the midgut epithelial cells are consistent with a destructive alkylation of cell structures by PII.

Summer weeds including established bermudagrass and nutsedge are of economic concern to alfalfa growers in western Arizona. Two replicated evaluations of norflurazon herbicide applications for summer weed control were conducted on established alfalfa fields in La Paz County. Zorial Rapid 80 WP and Evital 5G herbicides were tested for their effectiveness of bermudagrass and nutsedge control when applied following hay harvest but prior to irrigation in early spring. Zorial 80 WP was applied at 2.0 lb a. i. /acre. Evital 5G was applied at single application rates of 1.5, 2.0, and 3.0 lb a. i. /acre in spring and two split applications in spring and summer for a total of 2.0, 3.0, and 4.0 lb a. i. /acre. Norflurazon applications resulted in bleaching and shoot tip death of established bermudagrass 49 days after a single application (DAT), however by 78 DAT bermudagrass regrowth reinfested all plots resulting in zero control. Purple nutsedge control resulting from a single application of Evital 5G at 2.0 lb a.i./acre was 41, 82, and 35% at 35, 63, and 99 DAT, respectively. However, Zorial 80 WP applied at 2.0 lb a. i. /acre provided only 5, 23, and 0% purple nutsedge control at 35, 63, and 99 DAT, respectively. The limited effectiveness of the Zorial 80 WP spray solution for nutsedge control resulted from poor soil incorporation since the liquid was unable to penetrate the dense nutsedge foliage. The Evital 5G norflurazon formulation provided promising purple nutsedge control following one application to established alfalfa since the weight of the granules allowed the herbicide to reach the soil surface where irrigation could move the herbicide down through the soil profile to nutsedge roots. At 99 DAT a second split Evital treatment was applied to control nutsedge regrowth, and hopefully provide season long control. Nutsedge control results following this second split application are pending.

Plant growth regulators were aerially applied on April 26, 1996, to two alfalfa fields, one (Cibola) in its first year of production and the other field (CUF 101) in its third year. The first year field was approximately 50% through the cutting cycle and the third year field was approximately 30% through the cutting cycle when applications were made. No statistical differences were noted in hay tonnage the first cutting after application. Yield increases due to treatments were noted in the second cutting and maximum increases ranged from 277 -461 lbs of hay per acre. No yield or quality differences were noted the third cutting after application. The two fields differed in their response. The lowest rates of plant growth regulators produced higher yields in the first year field, but these treatment rates had greatly lowered hay quality the previous cutting. These effects were not noticed in the third year stand field. Increased hay tonnage was noted in the third year field from the 16 oz/acre rates, but was not evident in the first year field. Hay quality was usually highest in the check the first two cuttings after treatment. It is unknown if the differences noted between the two fields are due to different age of plants, variety and/or stage of growth when treatments were applied.

Some growers feel that nitrogen (N) fixing nodules found on the roots of the alfalfa plant are ineffective in cold soil during the winter and early spring. Thus, starter N fertilizer is commonly applied in late winter to established alfalfa to enhance growth until spring when the soil warms up and alfalfa begins actively fixing atmospheric N₂. Established alfalfa normally does not benefit from applications of N fertilizer since it is a leguminous crop that is capable of fixing its own N from atmospheric N₂. Afield experiment was conducted to determine the effect of N fertilizer applied in winter on alfalfa hay yield at the first cutting in spring. Two treatments consisted of an unfertilized check plot and UAN 32 water run at a rate of 35 lbs. N/acre to three year old 'CVF 101' alfalfa grown on a silt loam soil testing deficient in nitrate-N. Maximum alfalfa hay yield (J ton/acre) was obtained at the first spring cutting without N fertilizer application. However, since the field has a known yield potential of 1.5 ton/acre, factors other than fertility influenced the alfalfa hay yields observed in this study.

This experiment tested the effects of a cytokinin containing product (Dry Seed +) on CUF 101 alfalfa when applied with the seed at planting on October 24, 1996, at the rate of 1 /lb product to 100 lb of alfalfa seed. Data indicated a non - statistical yield response averaging 200 lbs an acrefrom treated fields the first cutting, valued at $11 /acre, but yields were identical the second harvest. Alfalfa quality means were very similar for both harvests. A positive net return of $9.76 /acre was noted by using Dry Seed +. More testing is suggested to confirm these findings.

Soil Sunburst was applied at the rate of one quart per acre at two treatment levels (single vs. two applications, applied once per cutting) in irrigation water to a first year stand of CUF 101 alfalfa. Treatments were applied in the first irrigation after the previous cutting in May and June 1996. Treatments applied in May increased relative feed value by over 10% compared to the untreated check in the first cutting (June) after application. This increased alfalfa quality rating from fair to good which increased value of hay by approximately $14 /acre. Mean yields between the treatments and untreated plots were similar, although average yields in untreated plots were 50-90 lbs /acre greater than in treated plots. Yields and quality data were not able to be obtained the second harvest (July), not allowing differences, if any, between one and two applications to be determined immediately after the second application. Yields and hay quality values for treatments in the August harvest were almost identical, indicating that treatment effects noted from the May application (and possibly those of the June application) were short term effects, as they did not continue through the August cutting.

The plant growth regulator Soil Triggrr was applied in basin flood irrigation water to the first (following previous cutting) and last irrigations of a third year stand of CUF 101 alfalfa before a late June 1995 harvest. Effect of product on yield may have been limited by pH as irrigation water pH was approximately 7.9. An increase in yield was noted with product usage, with a greater yield increase noted when applied earlier in crop cycle (first irrigation = 136 lbs hay /acre) rather than later in crop development cycle (last irrigation = 34 lbs hay /acre) when compared with the untreated check Yield from the next (July) harvest was not obtained Yield differences were not statistically different or economic for a single harvest in this experiment. Alfalfa quality was not obtained.

Research objective. Investigation of consistent patterns of the induction of flax morphogenesis process, assessment of genetic and physiological aspects of this process and optimization methodologies. Proposition: 1. MOrphogenesis capacity of flax isolated explants depends on a genotype only, but on a composition of a medium and the cultivar type (fibre flax or linseed)also. 2. Cells of different organs of the same genotype have different morphogenic capacity. 3. Combining hormonal ratio with the affect on explats by exogenic factors enables targeted control of the morphogenesis process in vitro. / Darbo tikslas - ištirti linų morfogenezės proceso indukcijos dėsningumus, įvertinti šio proceso genetinius ir fiziologinius aspektus bei optimizuoti regeneravimo metodikas. Ginamieji disertacijos teiginiai: 1. Linų izoliuotų eksplantų morfogeninė galia priklauso ne tik nuo genotipo, maitinamosios terpės sudėties, bet ir nuo veislės tipo (pluoštiniai ar sėmeniniai). 2.To paties genotipo skirtingų organų ląstelės turi skirtingą morfogeninę galią. 3.Derinant hormoninį balansą su eksplantų paveikimu egzogeniniais veiksniais galima kryptingai valdyti morfogenezės procesą in vitro.

Magistrantūros studijų baigiamajame darbe pateikiami lelijos (Lilium L.) morfogenezės indukcijos in vitro tyrimų duomenys. Darbo objektas: lelijų (Lilium L.) veislės ˈRed Beautyˈ, ˈWiener Blutˈ, ˈSėkmėˈ, ˈNoLimitˈ. Darbo metodai: lelijų (Lilium L.) izoliuoti eksplantai – svogūnėlių žvyneliai – auginti modifikuotoje MS maitinamojoje terpėje, kurios makro druskų koncentracija sumažinta iki 0,5 pradinio koncentracijos lygio, su skirtingais augimo reguliatorių deriniais. Vertintas mikrosvogūnėlių ir šaknų susiformavimo dažnis (%) bei mikrosvogūnėlių kiekis iš eksplanto (vnt.). Darbo rezultatai. Lelijų mikrosvogūnėlių formavimosi dažnį in vitro lemia augimo reguliatorių ir genotipo sąveika. Tos pačios lelijų veislės pasižymi skirtinga regeneracine galia, priklausomai nuo maitinamosios terpės sudėties. Iš tirtų veislių didžiausia regeneracine galia pasižymėjo veislės ˈRed Beautyˈizoliuoti eksplantai. Veislių ˈWiener Blutˈ ir ˈNo Limitˈ mikrosvogūnėlių regeneracijai in vitro maitinamąją terpę tikslinga papildyti 1,0 mg l-1 BAP + 0,3 mg l-1 2,4-D deriniu. Augimo reguliatorių derinys 2,0 mg l-1 BAP + 0,3 mg l-1 2,4-D labiausiai skatino veislės ˈRed Beautyˈ mikrosvogūnėlių susiformavimą. Veislės ˈSėkmėˈ izoliuoti eksplantai mikrosvogūnėlius formavo intensyviau augimo reguliatorių derinio 3,0 mg l-1 BAP + 0,3 mg l-1 2,4-D poveikyje. Intensyviausiai šaknis in vitro formavo veislių ˈRed Beautyˈ ir ˈWiener Blutˈ mikrosvogūnėliai. / The master work presents the results of increasing of lilies induction of morphogenesis in vitro studies. Object of the work: lilies (Lilium L.) cultivars of ˈRed Beautyˈ, ˈWiener Blutˈ, ˈSėkmėˈ, ˈNo Limitˈ. Methods of the work: Explants were cultured on the MS regeneration medium supplemented with macro salt concentration which is reduced to 0.5 of the initial concentration level, with different combinations of growth regulators. Evaluated for micro bulbs and root formation rate (%) and micro bulbs quantity of explant (units). The results of work. Lilies microbulbs formation in vitro is determined by the frequency of growth regulators and genotype interactions. The same varieties of lilies are characterized by different regenerative capacity, depending on the composition of the nutrient medium. Among investigated cultivars the highest morphogenic potention distinguished isolated explants of ˈRed Beautyˈ. For micropropagation of cultivars ˈWiener Blutˈ and ˈNo Limitˈ most suitable is medium supplement by 1,0 mg l-1 BAP + 0,3 mg l-1 2,4-D combination. Growth regulators combination 2,0 mg l-1 BAP + 0,3 mg l-1 2,4-D influenced cultivar ˈRed Beautyˈ. All isolated explants of cultivar ˈSėkmėˈ formed microbulbs on medium with 3,0 mg l-1 BAP + 0,3 mg l-1 2,4-D. The most intensive roots in vitro formed microbulbs varieties of ˈRed Beautyˈ and ˈWiener Blutˈ.