Grain sorghum [Sorghum bicolor (L.) Moench] varieties fail to reach maturity in North Dakota’s short and cool growing season. The study objective was to evaluate seeding date and white grain sorghum genotypes. A randomized complete block design study was conducted at Carrington, Oakes, and Prosper, ND, in 2018 and 2019. Genotypes included two commercial hybrids and four open-pollinated genotypes. Reaching heading and anthesis, hybrids required more heat units (GDDs), compared with the open-pollinated genotypes. Highest grain yield was obtained from the first and second seeding dates. Earlier-maturing open-pollinated genotypes maintained yield across seeding dates, whereas yield was reduced at later dates for the longer maturity hybrids. Hybrids produced the highest number of kernels per panicle at the first seeding date with fewer seeds at each successive seeding date. Although the open-pollinated genotypes out-yielded the hybrids at later seeding dates, the risk of lodging is too great to recommend their commercialization.

Bareroot and containerized loblolly pine (Pinus taeda L.) were planted in December 2016 and February 2017 to compare performance across four sites in South Carolina and Georgia. Main treatments analyzed for growth differences were stocktype, genetics, and planting date. Analysis of variance results showed significant growth differences after two growing seasons for containerized over bareroot seedlings, for control-pollinated seedlings over open-pollinated and varietal seedlings, and for December-planted seedlings over February-planted seedlings. Control–pollinated seedlings demonstrated the most incremental growth between ages one and two. Site conditions dictated seedling survival to a certain degree, and bareroot seedling growth was slightly better than containerized on the least stressful site. Results uncover important trends for main effects of stocktype, genetics, and planting date, but also underscore the importance for land managers to avoid blanket reforestation prescriptions, with more emphasis placed on site-specific conditions.

Thesis (M. A. Agricultural Management (Agricultural Extension)) -- University of Limpopo, 2019 / Smallholder farmers’ need for regular supply of adequate, quality and affordable seed led to the establishments of Community-Based Maize Seed Production Schemes (CBSPSs) in most developing countries, including South Africa. In view of the important influence of perception on the adoption and continued use of an innovation, this study was undertaken to evaluate farmers’ perceptions of CBSPSs in Polokwane and Lepelle-Nkumpi Local Municipalities of Limpopo province. The conceptualization of perception used in this study was based on the Düvel (1991) framework. The evaluation focused on whether planting the scheme’s main product, improved Open-Pollinated Varieties (improved OPV maize) seed meets farmers’ needs based on their perceptions and the extent of farmers’ planting of improved OPV maize. A census approach was used in view of the small numbers of seed producers in the schemes; all scheme members (50) were, therefore, interviewed between 27 March and 21 April 2017. To allow for comparison, an equal number of farmers (50) who were not members of the scheme were also interviewed. Data was collected from farmers using a semi-structured questionnaire. Descriptive and inferential statistics were applied to analyze the data using SPSS software. A binary logistic model was used to analyze factors that influence farmer perceptions on OPV benefits. The study findings showed that there is a significant relationship between awareness knowledge of improved OPV maize and planting of improved OPV maize. Furthermore, the results showed that farmers perceptions of the advantages and disadvantages of improved OPV maize seed were not different among scheme and non-scheme members as they were all in agreement that improved OPV maize have more benefits than their own previously recycled seeds. Finally, findings showed that respondents municipality and scheme membership had a significant, effect on the positive perception of planting improved OPV maize seeds. Other explanatory variables such as sex, farming experience, years of viii schooling, farm size, income and age of participants had no significant effect on farmer perceptions. It is therefore recommended that improved OPV maize be made widely available and promoted based on its advantages to enhance its adoption. Future studies on these seed schemes could look into the production and financial analysis of CBSPSs to ascertain their profitability and sustainability. / Agricultural Research Council (ARC)

Made available in DSpace on 2016-12-08T16:44:41Z (GMT). No. of bitstreams: 1 PGPV12MA096.pdf: 1514987 bytes, checksum: c0706020e05a268de58f6c3e9ec12e0a (MD5) Previous issue date: 2012-08-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Maize has low vegetative plasticity, because it normally does not tiller, it has limited capacity to expand the leaf blade and it does not alter the number of expanded leaves due to changes in environment or management. Therefore, damages in leaf area caused by defoliation can decrease grain yield and increase the occurrence of base stalk rots (BSR) and rot grains (RG), reducing grain quality. The cultivar`s genetic variability may interfere on the extension of damages caused by defoliation. This research was carried out aiming to quantify grain yield losses and the effect on base stalk rot (BSR) and rot grains (RG) caused by defoliation at different growth stages of maize cultivars with contrasting genetic variability. A field experiment was set in Lages-SC, during the growing seasons of 2010/11 and 2011/2012. Three cultivars were tested: the open pollinated variety (OPV) SCS 155 Catarina, the triple hybrid (TH) P30B30 and the single-cross hybrid (SC) P30R50H. Each cultivar was defoliated when plants had eight (V8), 12 (V12), 16 (V16) and 20 (V20) expanded leaves. A control treatment without defoliation was also assessed. The experiments were sown in the no-tillage system on 10/22/2010 and 10/19/2011. The plant density of 60,000 pl ha ֿ1 and the row spacing of 0.7 m were used in the trial. Defoliations performed at V8 and V12 did not affect the SC and TH grain yield, but they decreased the OPV productivity. The defoliation performed at V20 reduced by more than 70% the grain yield of all cultivars. The removal of eight and 12 leaves did not increase the incidence of BSR and the percentage of broken plants in comparison to the control. Late defoliations performed at V16 V20 weakened the stalk, increasing the occurrence of BSR and broken plants for the three cultivars. The greater genetic variability of OPV SCS 155 Catarina was not efficient to minimize grain yield losses caused by defoliation, neither to decrease the incidence of base stalk rot nor rot grains, in comparison to the hybrids P30B30 and P30R50H / A cultura do milho possui baixa plasticidade vegetativa, pois normalmente não perfilha, apresenta limitada capacidade de expansão do limbo foliar e não altera o número de folhas expandidas devido a mudanças no ambiente ou no manejo. Os danos na área foliar ocasionados pela desfolha podem reduzir o rendimento de grãos e aumentar a ocorrência de podridões da base do colmo (PBC) e de grãos ardidos (GA), depreciando a qualidade dos grãos. A variabilidade genética da cultivar pode interferir na magnitude dos danos ocasionados pela desfolha. Esta pesquisa teve como objetivos quantificar os prejuízos no rendimento de grãos e a influência sobre PBC e GA, ocasionados pela desfolha imposta em diferentes estádios fenológicos em cultivares de milho com bases genéticas contrastantes. O experimento foi conduzido a campo, no município de Lages-SC, nos anos agrícolas de 2010/11 e 2011/12. Foram testadas três cultivares de milho: a variedade de polinização aberta (VPA) SCS 155 Catarina, o híbrido triplo (HT) P30B30 e o híbrido simples (HS) P30R50H. Cada cultivar foi desfolhada quando as plantas tinham oito (V8), 12 (V12), 16 (V16) e 20 (V20) folhas expandidas e foi mantida uma testemunha com folhas intactas. Os experimentos foram implantados no sistema de semeadura direta, em 22/10/2010 e 19/10/2011. A densidade utilizada foi de 60.000 plantas ha-1 e o espaçamento entre linhas de 0,7m. As desfolhas realizadas em V8 e V12 não comprometeram o rendimento de grãos do HS e do HT, mas reduziram o rendimento da VPA. A desfolha realizada em V20 reduziu em mais de 70% o rendimento de grãos das três cultivares. A remoção de oito e 12 folhas não aumentou a incidência de PBC e a percentagem de plantas quebradas, em relação à testemunha. As desfolhas mais tardias (V16 e V20) aumentaram a ocorrência de PBC e de plantas quebradas das três cultivares. A maior variabilidade genética da VPA SCS 155 Catarina não foi eficaz para minimizar as perdas ocasionadas pela desfolha no rendimento de grãos, nem tão pouco para diminuir a incidência de podridões da base do colmo e grãos ardidos, em comparação aos híbridos P30B30 e P30R50H

Farmer-led seed systems (FSS) provide the backbone for small-scale farmers and many rural communities that use traditional methods of farming to produce seeds that grow and adapt to local conditions. FSS differ from one community and farmer to the next, depending on the methods and practices used to maintain seed varieties. Seed diversity can enhance FSS by improving livelihoods and strengthening farmers' networks, thus contributing to resilient communities. Although nuanced, the dualistic agricultural system in South Africa consists largely of subsistence (small-scale) and commercial (large-scale) farming and includes different crop management systems and post-harvest practices. In South Africa, maize (Zea mays) is a major staple grain crop with a significant role as animal and poultry feed. The North West region is one of the highest white-maize-producing provinces in South Africa. Maize seed systems include both traditional, openpollinated varieties (OPVs) and cultivars such as modern hybrids and genetically modified (GM) seed varieties, including those engineered for specific purposes. The dominant GM maize is that designated for pest resistance using Bacillus thuringienesis (Bt), a soil bacterium which produces a toxin that is fatal to a wide variety of insects such as moths and flies. Many small-scale farmers prefer their own traditional seeds for breeding, planting, selection, selling and consuming. However, FSS based on traditional varieties are threatened by modern cultivars which may be introduced in different ways including through seed exchange, purchasing at shops or by pollination from nearby commercial farms. This study was conducted in the Sespond community of the North West Province. The aim of the study was to understand how small-scale farmers in Sespond maintain traditional maize varieties through selection and storage in a complex agricultural landscape that incorporates both formal and informal seed systems. The formal system represents industrialised farms and companies that work with commercial seed. The informal system represents small-scale farmers who rely on their own seed. Qualitative methods included mapping software which was used to obtain visual agricultural data in and around Sespond. Semi-structured interviews were conducted with 30 small-scale farmers to collect information about their farming practices, including the maize varieties planted. Quantitative methods included collecting 20 maize samples from different farmers for genetic analysis. Agdia® immunostrip tests were used to detect for the presence of Crystal protein (Cry protein) produced by the Bt bacterium, engineered to improve the resistance of maize against insects. The results showed that 13 samples were negative for the protein and seven samples were positive for the protein. A key finding is that small-scale farmers are not able to detect the different maize varieties in their seed systems. This represents a threat for traditional seed varieties in the community as without this knowledge, farmers are not able to adequately manage their production and storage systems. Farmers made use of alternative storage methods such as the mill to reduce seed damage they experienced at home. However, the findings of this research showed that there was an increasing risk of farmers' traditional maize being mixed with GM maize at the mill. Farmers' rights to plant and consume traditional maize were therefore undermined. This study recommends that (a) efforts are made to increase awareness among farmers that help to distinguish transgenes from hybrids and traditional maize varieties; (b) measures are implemented at mills to both improve the transparency about the storage and processing of traditional maize and to separate traditional maize from hybrid and GM maize.

Decades of tree improvement has resulted in genetic gains in loblolly pine productivity, form, and resistance to fusiform rust. The goal of this study was to advance the understanding and applied use of genetic improvement by analyzing inter- and intra-provenances hybrids’ rust resistance and evaluating midrotation performance of varying levels of genetically improved stock types. The first study compares 16 seedlots at the USDA Resistance Screening Center and evaluates rust resistance of controlled-pollinated inter- and intra-provenances crosses, and openpollinated seedlots from three provenances: Western Gulf, Atlantic Coastal, and Interior Piedmont. Post inoculation, one Coastal OP seedlot was resistant and ten of the seedlots were susceptible to the disease. The second study compares three levels of improved stock types: second-generation open-pollinated, controlled pollinated, and varietal material. After the fifteenth growing season, all three improved stock types were not significantly different from one another in defects, height, diameter, volume, and exhibited site index.