No description available.

Switchgrass (Panicum virgatum) is a native warm-season grass where weed control during establishment is a limiting factor for stand. Objectives of this research are to develop a herbicide resistant cultivar and to test a variety of seed safeners to improve first year growth. Phenotypic recurrent selection (PRS) was used to select ‘Alamo’ switchgrass seedlings that showed resistance to imazapic herbicide at 245 g a.i./ha. Initial screenings of 364, 650 seedlings resulted in 63 survivors, a selection intensity of 0.0172%. Subsequent testing of the next generation of seedlings indicated that multiple generations of selection were needed in order to transfer greater resistance to the offspring. Seed safener testing consisted of three trials. Field data taken included emergence counts, weed control ratings, and end of season harvest. Results showed fluxofenin (a.i. in Concep III) as being only safener providing protection against metolachlor (83.7% a.i.).

No description available.

Efficient plant regeneration and transformation procedures and the stability of the transgene are important to the success of the cotton and soybean biotechnology industry. Engineering herbicide resistance into plants will provide the potential solution to effective weed control in agriculture and reduce loss in crop yields due to weeds. It will also provide cheaper control and decrease environmental hazards. The aims of this study were to develop efficient regeneration and transformation protocols for commercially grown soybean and cotton in South Africa and to use tobacco as a model plant to study the stability of the pat gene through seed generations, successive generations and high temperature and drought stress regimes. Tobacco (Nicotiana tabacum cv. Samsun) leaf disks were successfully transformed with the pat gene. PCR analysis confirmed the integration of the pat gene in all nine transgenic plants and T1, T2 and T3 progeny. Successive generations, high temperatures and drought stress had no adverse effect on the stability and expression of the pat gene in the transgenic tobacco plants. In view of the economic importance of soybean (Glycine max) and cotton (Gossypium hirsutum) in South Africa and the potential to improve commerciallygrown cultivars by genetic transformation, a regeneration and transformation protocol using the shoot apical meristem and Agrobacterium-mediated DNA transfer was successfully developed, to obtain herbicide (Basta) resistant commercially-grown South African soybean and cotton plants for the first time. The frequencies of regenerated plants per meristem were 66% for Talana, 52% for Ibis, 90% for Sabie, 74.6% for LRCC 101, 69.5% for Palala and 70% for 107/1. Prior to transformation experiments, Talana and Ibis were screened for susceptibility to virulent Agrobacterium tumefaciens sis 43. Both cultivars produced tumours in response to infection and were therefore compatible hosts for Agrobacterium-mediated DNA transfer. Transformation of Talana, Sabie and 107/1 with the pat gene, was successfully achieved following wounding of the shoot apical meristem and injecting with Agrobacterium in the presence of acetosyringone. Transformed explants and shoots grew in the presence of kanamycin and PPT, indicating that the integrated pat gene was producing the enzyme PAT which was successfully detoxifying the herbicide PPT. Final transformation frequencies from the initial transformed meristems to regenerated plants were 1.06% for Talana, 2.3-3% for Sabie and 1.2-2.3% for 107/1. These transformation frequencies were higher than those reported in the literature. PCR analysis of the extracted DNA from transgenic soybean and cotton shoots confirmed the presence of the 558 bp pat coding region in the transformed plants. The success of this study on the regeneration and transformation of soybean and cotton indicates that South African agriculture now has available techniques for plant regeneration and recombinant DNA technology for crop improvement of soybean and cotton.

Typescript (photocopy) / Bibliography :leaves 310-329. / ix, 329 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1994

Bibliography: leaves 143-161. / xi, 161 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Pot exmeriments are undertaken during the winter growing season to examine Paraquat and Diquat resistance in the grass weed species Hordeum leporinum Link., H. glaucum Steud. and Vulpia bromoides SF Gray, and in the broadleaf weed Arctotheca calendula (L.) Levyns. / Thesis (Ph.D.)--University of Adelaide, Dept. of Crop Protection, 1994

Bibliography: leaves 143-161. Pot exmeriments are undertaken during the winter growing season to examine Paraquat and Diquat resistance in the grass weed species Hordeum leporinum Link., H. glaucum Steud. and Vulpia bromoides SF Gray, and in the broadleaf weed Arctotheca calendula (L.) Levyns.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 35-40). Also available on the World Wide Web.

There is little information published on red sorrel (Rumex acetosella L.), a perennial weed that is considered a serious problem in wild blueberry production. Hexazinone, a photosystem II inhibitor, has been used in wild blueberry fields for more than 30 years. Hexazinone efficacy on red sorrel has declined over time. Therefore, a two year study was conducted to examine hexazinone alternatives that can be sprayed in wild blueberry fields. Red sorrel ramets from mature blueberry fields were tested to determine whether long-term spraying of hexazinone selected for resistant red sorrel. The results show that hexazinone+rimsulfuron/nicosulfuron may be a alternative for hexazinone. Red sorrel from some blueberry fields is hexazinone-resistant and the resistance is caused by a Phe255 to Val mutation in the psbA gene.

In recent years global concern over the development of herbicide resistant (HR) weeds has lead to interest in integrated weed management (IWM) strategies. IWM seeks to relieve selection pressure for herbicide resistance by utilizing mechanical and cultural controls in addition to herbicides. The situation experienced by Saskatchewan lentil growers with large populations of group 2 herbicide resistant wild mustard provides an ideal model system to test our hypothesis that IWM strategies can provide robust weed management and maintain crop yields. The first study evaluated an IWM method targeting HR wild mustard in lentil. This study was conducted for 3 years between 2011 and 2013 at 2 locations at Saskatoon and Scott, Saskatchewan. It was a randomized two way factorial with weed control method and seeding rate as the main effects. Weed control treatments tested consisted of a control treated with a glyphosate burnoff, saflufenacil (Heat ™) herbicide, rotary hoeing, half rate metribuzin (Sencor ™) herbicide, a fully integrated treatment, and a full herbicide treatment. Three seeding rates representing 1, 2, and 4 times the recommended seeding rate were tested. The integrated treatment relied on increased seeding rate to reduce mustard biomass and produce yield, and at the highest seeding rate it was able to provide equivalent yield to the full herbicide system. The results of this study show that an integrated system utilizing an increased seeding rate can control resistant weeds and maintain yields to a similar level as a strategy that relies only on herbicides for weed control. The cultural practice of increasing crop seeding rate has been identified as having potential to provide non-chemical weed control and enhance the effects of herbicide application. The objective of the second study was to examine the interaction between increasing seeding rate and the dose response relationship of weeds to herbicide application. The experiment was a factorial design with four levels of lentil seeding rate and seven levels of fluthiacet-methyl herbicide application rate. The study was conducted at two locations near Saskatoon, Sk. in 2012 and 2013. Results of the experiment show that increasing lentil seeding rate decreased the total mustard biomass when herbicides were not applied or were applied at low rates. In addition increasing lentil seeding rate lowered the herbicide dose required to result in a 50% reduction in mustard biomass in 2012, though it had little effect in 2013. These results suggest that the practice of increasing seeding rate can work with herbicide application to reliably and effectively control weeds, even in situations where herbicides alone may not achieve good control.