CHARACTERIZATION OF SALT AND DROUGHT TOLERANCE IN SUNFLOWER (Helianthus annuus L.)

Consequent to the increasing world population, food sources are needed to be increased to meet the nutritional needs. However, due to natural processes and agricultural activities, the most destructive environmental factors that limit crop production, soil salinity, and drought-exposed areas are growing. As one of the major oilseed crops, sunflower (Helianthus annuus L.), is considered to be moderately tolerant to salt and drought. Although it can grow in arid to semi-arid regions, increasing salinity and drought might adversely affect sunflower production. This study aimed to investigate several sunflower germplasms\u27 morphological responses to salt and drought stresses. For this purpose, greenhouse and field trials were conducted at University of Nebraska-Lincoln facilities during 2020-2021. For the greenhouse salinity experiment, germplasms PI 539899, PI 539900, PI 539901, PI 539902, PI 539903, and PI 599984 were used and exposed to three different salt concentrations (0, 150, and 250 mM). In addition, PI 632338/HA 429 and PI 632339/HA 430 were tested for drought response under three different irrigation levels for drought experiments in both greenhouse and field. For the greenhouse, treatments consisted of full irrigation (2L/pot), limited irrigation of 50% (1L/pot), 25% irrigation (.5L/pot), and while for the field, full irrigation treatment (FIT), limited irrigation treatment (LIT), and rain-fed (RF) treatments were applied. In the greenhouse experiments, while the plant height was observed as the highest under the 150 mM salinity treatment, it was seen in the 50% irrigation treatment for the drought experiment. The salt treatment effect was significant with the Soil Plant Analysis Development (SPAD), and the Normalized Difference Vegetation Index (NDVI) with a downward trend over time, and canopy temperature showed an upward trend for salinity and drought trials. In the field experiment, irrigation treatments were not found significant for over time data, however, the effect of time was significant in all data sets, while the germplasm effect and its interaction on canopy temperature, and NDVI was significant. In the salinity experiment, the treatment effect was found to be significant for dry root and shoot weight, while only the germplasm effect was found statistically significant for dry head weight. Different irrigation treatments for the greenhouse drought experiment were only significant for dry shoot weight and head weight. In the field trial, the highest values for head diameter, head weight, whole seed weight g/head, and hundred seed weight were observed in full-irrigated plants. Post-harvest data for the field experiment, different irrigation applications significantly affected the oil amount, and not the crude protein and fatty acids composition. This study indicated that there are differences in genotypes\u27 response to both drought and salinity that could be used for sunflower improvement. Advisor: Ismail Dweika

Ecology and genomics of an important crop wild relative as a prelude to agricultural innovation

Domesticated species are impacted in unintended ways during domestication and breeding. Changes in the nature and intensity of selection impart genetic drift, reduce diversity, and increase the frequency of deleterious alleles. Such outcomes constrain our ability to expand the cultivation of crops into environments that differ from those under which domestication occurred. We address this need in chickpea, an important pulse legume, by harnessing the diversity of wild crop relatives. We document an extreme domestication-related genetic bottleneck and decipher the genetic history of wild populations. We provide evidence of ancestral adaptations for seed coat color crypsis, estimate the impact of environment on genetic structure and trait values, and demonstrate variation between wild and cultivated accessions for agronomic properties. A resource of genotyped, association mapping progeny functionally links the wild and cultivated gene pools and is an essential resource chickpea for improvement, while our methods inform collection of other wild crop progenitor species

Data from: Ecology and genomics of an important crop wild relative as a prelude to agricultural innovation

Domesticated species are impacted in unintended ways during domestication and breeding. Changes in the nature and intensity of selection impart genetic drift, reduce diversity, and increase the frequency of deleterious alleles. Such outcomes constrain our ability to expand the cultivation of crops into environments that differ from those under which domestication occurred. We address this need in chickpea, an important pulse legume, by harnessing the diversity of wild crop relatives. We document an extreme domestication-related genetic bottleneck and decipher the genetic history of wild populations. We provide evidence of ancestral adaptations for seed coat color crypsis, estimate the impact of environment on genetic structure and trait values, and demonstrate variation between wild and cultivated accessions for agronomic properties. A resource of genotyped, association mapping progeny functionally links the wild and cultivated gene pools and is an essential resource chickpea for improvement, while our methods inform collection of other wild crop progenitor species

Data from: Ecology and genomics of an important crop wild relative as a prelude to agricultural innovation

Domesticated species are impacted in unintended ways during domestication and breeding. Changes in the nature and intensity of selection impart genetic drift, reduce diversity, and increase the frequency of deleterious alleles. Such outcomes constrain our ability to expand the cultivation of crops into environments that differ from those under which domestication occurred. We address this need in chickpea, an important pulse legume, by harnessing the diversity of wild crop relatives. We document an extreme domestication-related genetic bottleneck and decipher the genetic history of wild populations. We provide evidence of ancestral adaptations for seed coat color crypsis, estimate the impact of environment on genetic structure and trait values, and demonstrate variation between wild and cultivated accessions for agronomic properties. A resource of genotyped, association mapping progeny functionally links the wild and cultivated gene pools and is an essential resource chickpea for improvement, while our methods inform collection of other wild crop progenitor species