No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Cary L. Rivard / As populations of cities continue to increases, communities in the United States are implementing urban food systems including locally-cultivated produce. Urban and peri-urban farmers apply intensive production systems, including high tunnels, to better utilize limited space. Grafting tomato with vigorous rootstocks provides the potential for higher yields. Our first objective was to identify tomato rootstocks that improve productivity in high tunnel environments with no soilborne diseases in the Central U.S. Eight replicated high tunnel trials were conducted at four sites in northeastern Kansas in 2013 and 2014. We selected 'BHN 589' scion for all sites and evaluated seven rootstocks. Grafting with ‘Maxifort’, ‘Multifort’, ‘Arnold’, ‘DRO 131’, and ‘Colosus’ rootstocks resulted in significant increases in total fruit yield, which ranged from 40% to 73% when compared to nongrafted plants (P<0.05). No significant increases in yield were observed for ‘RT-1028’ and ‘RST-04-106’ rootstocks. Our results suggested that tomato growers that utilize high tunnels should be strategic when selecting rootstocks. Our second objective was to develop simple propagation techniques that yield high quality grafted transplants for small-batch propagators. Formation of adventitious roots (AR) from the scion can result in poor quality plants and loss of rootstock function/benefit. Greenhouse studies were designed to investigate how leaf removal (LR) affects AR formation and plant growth post-grafting. We applied three treatments, 0% LR, 50% LR, and 90% LR, to the ‘BHN 589’ scion and then grafted them onto ‘Maxifort’ rootstock. The experiment included 4 replicated blocks and was conducted in three different healing chambers. Our results indicate that both 50% and 90% LR significantly decreased AR formation in the low humidity chamber, but only 90% LR reduced AR formation in the chambers with high humidity (P<0.05). We measured plant growth 24 to 52 days post-grafting to understand how leaf removal affects transplant quality, growth, and development. Plants with 90% LR had significant growth reduction at day 24 but at day 52, only had reduced stem diameter and height compared to 0% LR. Total flower count was the same for all treatments. Leaf removal during grafting may be a viable method for propagating high quality, grafted transplants.

Thesis (M. Sc. (Biochemistry)) -- University of Limpopo, 2003 / Refer to document / National Research Foundation (NRF)

Thesis (M.Sc. Agriculture (Plant Production)) -- University of Limpopo, 2014 / The management of root-knot nematodes (Meloidogyne spp.) has become a challenging task in tomato (Solanum lycorpesicum) production, due to the withdrawal of effective chemical nematicides. Currently, crude extracts of different plant species are being researched as alternative to chemical nematicides, with promising results. The objective of this study was to determine the effect of crude extracts of wild garlic (Tulbaghia violacea) on the growth of tomato under greenhouse conditions, and the suppression of M. incognita race 2 population densities. Treatments consisted of four levels of crude extracts viz. 0, 2, 4 and 8 g per pot, were arranged in a randomised complete block design with 10 replicates. Seedlings were inoculated with 1000 juveniles of M. incognita race 2 at transplanting and treated with crude extracts two days later. At 56 days, the crude extract of T. violacea increased plant height, stem diameter, number of cluster, flowers, fruits and leaves by 43-73%, 108-200%, 57-81%, 55-110%, 170-223% and 51-66%, respectively. It also increased the root mass and shoot mass by 95% and 96%, respectively. Crude extracts of T. violacea did not have any effect on soil pH and electrical conductivity (EC). Crude extracts of T. violacea consistently reduced population densities of M. incognita race 2 by 50, 64 and 73% in roots at 2, 4 and 8 g crude extracts, respectively and by 21, 30 and 58% in soil at similar levels, respectively. In conclusion, crude extracts of T. violacea have the potential to improve growth of tomato plants and suppress population densities of M. incognita race 2 and could be used as botanical nematicide in tomato production.

Tomato bushy stunt virus (TBSV) is a positive-sense single-stranded RNA virus. It encodes five open reading frames (ORFs), including two nested genes, expressing movement-associated proteins. One of these proteins, P22, interacts with a host transcription factor containing a homeodomain leucine-zipper motif, known as HFi22. Similar proteins of this type traffic their RNA from cell-to-cell, suggesting the possiblity that HFi22 is involved in the cell-to-cell movement of TBSV RNA. To further characterize the nature of the interaction between P22 and HFi22 on the cellular level, cellular fractionation experiments were conducted. To investigate the functional role of HFi22 in viral movement I attempted to inactivate its expression using a virus induced gene silencing system with a Tobacco rattle virus (TRV) vector. A final objective was based on the notion that different hosts can impact the stability of viruses used to express foreign genes of biotechnological interest. To compare virus stability in different hosts, TBSV expressing the green fluorescent protein (GFP) was inoculated onto various TBSV hosts, and infected leaf tissue was then used as inoculum to be rubbed onto a local lesion host. This technique made it possible to quantify the number of fluorescent foci versus total lesions. Results obtained for the first objective indicate that P22 and HFi22 co-fractionate in nucleus and membrane-enriched samples. In addition, it was found that HFi22 is largely conserved through a wide variety of plant species but not in lettuce, which was found to be compromised for effective virus spread. Control experiments for the second objective showed that plants were successfully silenced with TRV carrying the phytoene desaturase (PDS) gene resulting in photobleaching, however attempts to silence HFi22 have not yielded conclusive results. The results obtained for the third objective indicate there is a difference in how efficiently a foreign gene insert is maintained by TBSV in different host plants. In summary, the overall results of this research showed that host factors influence the host-virus interaction but their exact contributions remain elusive.