Optimizing Brassica carinata disease management to protect against yield loss due to Sclerotinia stem rot
Advisor: Ian Small
Sclerotinia sclerotiorum is a plant pathogen with a wide host range that causes stem rot on Brassica carinata (carinata). The impact on yield and integrated disease management strategies have not been well established for Sclerotinia stem rot (SSR) disease of carinata. The objectives of this study were to 1) determine the optimum growth stage to apply a fungicide for managing SSR on carinata, 2) relate SSR with carinata yield, and 3) quantify impacts of cultural management practices for SSR, including crop rotation and variety resistance. Four carinata varieties (whole plot) were planted at the UF/IFAS NFREC in Quincy over four seasons in the same field in a RCB split-plot design. The fungicide Proline was applied at different growth stages (subplot). SSR incidence and severity was assessed in two 1 sq m quadrants/plot for a Sclerotinia disease severity index (DSI) calculation. Early to full flowering, before or just as petals begin to drop (<10%), was found to be the optimum carinata growth period to apply a fungicide for controlling SSR, but seasonal differences and history of disease can affect the magnitude of control. Applying a fungicide at early flowering resulted in higher yield compared to the non-treated control in seasons 2020 and 2021. The increase from a non-treated average of 12% SSR DSI in 2018 and 2019 to 49% in 2020 that remained at 40% in 2021 suggests a need for rotation with a non-susceptible crop. Due to the impact of SSR on yield that can vary by season and cultural practices, optimal management including efficient fungicide inputs and crop rotation can contribute to the economic and environmental sustainability of Brassica carinata.
Rebeca Sandoval Ruiz
Fighting reniform nematodes with Brassica Carinata
Advisor: Zane Grabau
Rotylenchulus reniformis (reniform nematode, RN) is a plant-parasitic nematode that negatively affects crop yield, especially in cotton. Crop rotation could be a more environment-friendly management strategy against RN than the traditional use of chemicals. An effective rotation crop does not facilitate nematode populations to increase, for example, it should act as a poor host crop—a crop that a particular nematode has minimal reproduction on— or have biofumigant properties. Biofumigation is the use of biologically active compounds of a plant against a pathogen, like nematodes. Brassicas are considered biofumigant crops because of the presence of glucosinolates, but efficacy under field conditions may vary. In the Southeast United States, there is an emerging Brassica winter crop, called Brassica carinata (carinata, Ca), that could have the properties necessary to manage RN. Nevertheless, no previous studies have been done to evaluate if carinata may help manage RN. For this reason, the objectives of this research were: 1) to define the status of Ca as a RN host, 2) to compare the biofumigation, on RN, by Ca with those from other winter crops, under greenhouse conditions, and 3) to determine the effect of Ca, used as a winter rotation crop, on RN in field conditions. For the first objective, crops with known host status for RN, including canola, cotton, hairy vetch, oats, and peanut, were used to compare RN reproduction on Ca under greenhouse conditions. RN populations did not increase on Ca, and the number of RN from Ca was separated from the crops defined as good hosts (cotton and hairy vetch), suggesting it is a poor host of RN. For the second objective, winter crops were Ca, hairy vetch, oats, and canola. Shoot and root residues were applied at 2% dry or fresh tissue by weight relative to soil weight. Cotton was planted in each pot one week after the organic matter (OM) incorporation. The number of RN nematodes juveniles and eggs was counted. In general, the number of RN recovered from the cotton plants in which the dry tissue was incorporated was lower than from the plants in which the fresh tissue was applied. Additionally, the number of RN was lower in the plants in which Ca was applied as a dry tissue, compared to the dry OM from the other crops used. For the third objective, a 4-year field crop rotation study was established in Quincy, Florida. The winter crops were two-year rotations of Ca-fallow, oats-Ca, and fallow-fallow. The summer crops were corn-cotton-peanut-soybean, with all crops present each year. Nematodes were enumerated in spring and fall. The general trend was that when Ca was part of the winter rotation system, the number of RN was lower than for the fallow-fallow rotation. In conclusion, carinata seems to be a non-host crop of RN, has biofumigant properties against RN when applying to the soil, and can help to manage RN when used as part of the field winter rotation system. More research will be done to confirm the results.
Nitrogen use efficiency among genetically diverse set of carinata genotypes
Advisor: Michael Mulvaney
Brassica carinata, an alternative non-food oilseed crop, is used to produce aviation biofuels due to its high oil content and favorable fatty acid profile. Maximizing yield for commercial production of Brassica carinata in the southeast United States (SE US) requires management of soil nitrogen (N) availability, the quantitatively most important nutrient required for crop growth which is insufficient in soils of the SE US and must be supplied as fertilizer. To ensure the competitiveness of Brassica carinata at agronomic, environmental, and economic levels, it is necessary to develop carinata cultivars with improved N stress tolerance and high seed and oil yield under low soil N availability. This involves identifying carinata genotypes with superior nitrogen use efficiency (NUE), either by possessing a high N uptake efficiency (NUpE) or high N utilization efficiency (NUtE), or both. A greenhouse study was conducted in Quincy FL to quantify genotypic variation in NUE and to identify indicators of N efficient genotypes during 2019/2020 growing season. Seed yield, biomass, NUE, NUpE, and NUtE were compared among 16 genetically diverse carinata genotypes under contrasting N supplies (0, 80.5, and 161 mg N L-1 in Hoagland solution). Preliminary results show significant differences among the genotypes for seed yield and NUE under contrasting N regimes. NUtE contributed to high seed yield under low and high N levels, making it more important than NUpE for achieving NUE in carinata under low N.
Brassica carinata nutrient uptake and partitioning across maturity groups and latitudes
Advisor: Michael Mulvaney
There are limited data regarding temporal nutrient accumulation and partitioning dynamics of Brassica carinata (carinata). As a recently introduced crop in the US, such studies inform the rate of macro and micronutrient accumulation and will aid fertility management decisions in carinata. A study was conducted during 2018-2019 and 2019-2020 growing season in Florida, US and in North Carolina, US to quantify seasonal long carinata biomass, nutrient accumulation and partitioning in southeastern (SE) US conditions. Three genotypes (DH-157.715, M-01, and Avanza 641) with variable maturity as identified by the Nuseed Inc., breeding program (formerly Agrisoma Inc.,) were sampled at multiple growth stages and partitioned into leaves, stems, reproductive parts (flowers plus pods), and seed to determine biomass and nutrient accumulation across three genotypes in Florida and one full season genotype in North Carolina. There were no significant differences among genotypes for biomass and nutrient accumulation for majority of nutrients. All subsequent analyses were performed for two site-years and genotypes combined as a random effect in FL and were combined over two site years for commercial variety Avanza-641 in NC. Preliminary results indicate that the nutrient management practices may not differ among the proposed maturity classes in the southeastern US conditions. However, timing of nutrient application (particularly N) for the commercial variety Avanza-641 may differ across Jay, FL and Salisbury, NC to mitigate deleterious effects of freeze damage. These results inform temporal nutrient accumulation and partitioning dynamics in carinata to ensure adequate nutrient availability.
Brassica carinata (A.) Braun tolerance to preemergence and postemergence herbicides
Advisor: Ramon Leon
Brassica carinata (A.) Braun, or carinata, is an oilseed crop that is currently being developed for biofuel production. Southeastern growers have been interested in growing carinata as a winter crop because of biofuel industry demand and potential use as a rotational crop. As a new crop, there are minimal herbicides registered for use in carinata, so a preliminary screening was used to identify herbicides for safe use in carinata. Thus, the main objective of this study was to assess the safety of select preemergence and postemergence herbicides at varying rates on carinata seedling establishment and plant growth. The preemergence herbicides used were diuron, clomazone, and napropamide. The postemergence herbicides used were simazine and clopyralid. Preemergence herbicides were applied at planting and postemergence herbicides were applied at the 4- to 6-leaf stage. The rates that were tested were 0.25X, 0.5X, 1X, 2X, 4X and 8X the recommended label rate for each herbicide. The results indicated that despite high levels of bleaching and chlorosis, clomazone did not reduce yield at the 1X and lower rates compared with the non-treated control. Napropamide and clopyralid seem to be safe at label rates, but more research is needed due to high levels of variation depending on location. Conversely, diuron and simazine caused high levels of injury and yield loss at most rates, so these herbicides could be used for control of volunteer carinata in rotational crops. This research of herbicide tolerance will give southeastern growers herbicide regimens to allow the reduction in physical, environmental, and economic constraints in order to produce carinata for renewable fuels and bioproducts.
Mixotrophic cultivation of Chlorella vulgaris using Brassica carinata hydrolysate as carbon source for biomass and lutein production
Advisor: George Philippidis
Brassica carinata is a nonedible oil seed crop that is utilized in the production of renewable aviation fuel, organic acids, and other chemicals. The solid residue remaining after oil extraction from the seeds is referred to as meal which is enriched in protein and carbohydrates. While meal protein is often used as animal feed, the carbohydrate content can also be utilized to further valorize the bioeconomy of carinata. Through pretreatment and subsequent hydrolysis of carinata meal, the cellulosic biomass was converted to readily fermentable glucose. This glucose rich hydrolysate was utilized as media for chlorella vulgaris UTEX 26 in cultivating high lipid and lutein productivity. Using thermochemical bioconversion strategies, the sugars present in carinata meal hydrolysate can be utilized in the cultivation of chlorella vulgaris UTEX 26 for lipid and lutein production which can be applied in biofuels and health supplements. Lipid, lutein, carbohydrate, and protein content are discussed as well as the effects the concentration of hydrolysate plays on overall productivity. The experimental results demonstrate the enhanced abilities carinata meal hydrolysate has on the high lipid production and biochemical composition of chlorella vulgaris UTEX 26.
Lignin-Based and Disulfate-Linked Aerogel as a Selective, Controllable, Reusable Superabsorbent
Advisor: Zhaohui Tong
Oil spills pose a large threat to marine ecosystems. The current cleanup methods include chemical dispersion agents, in-situ burning, and collection of oil from the water surface through physical processes. These current methods are harmful to the environment and can be extremely costly and time consuming. Therefore, an ecofriendly, highly efficient, and excellent absorbent is needed. Here, a potential oil absorbant was successfully prepared by a mild method of modified Alkali Lignin (EAL), trimethylolpropane tris(3-mercaptopropionate) (TMMP) in dimethyl sulfoxide (DMSO) catalyzed by sodium hydroxide (NaOH). The formation of oil-absorbent properties were confirmed by Fourier Transform Infrared (FTIR) Spectroscopy, Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Brunauer–Emmett–Teller (BET). The oil removal capacity was performed at different contact times in an oil as well as oil/water mixture, and the sponge showed hydrophobicity as well as a high adsorption capacity up to 4.35g oil/g absorbent for Paraffin oil. The absorbant was made using different percent ratios of lignin to DMSO to create different pore sizes and evaluate the impact on oil absorption. It was found that the 3% ratio of lignin to DMSO yielded the highest absorption capacity. The absorbant can also be washed with an organic solvent and reused for additional oil absorption.