ASHS 2024 Conference

Bermudagrass (Cynodon spp.) is a prominent warm-season turfgrass extensively utilized across golf courses, athletic fields, home lawns, and recreational areas due to its excellent heat tolerance, good traffic tolerance, and strong recuperative potential. Despite its strengths, winter survivability in colder climates remains a concern. Research has revealed variations in freeze tolerance across bermudagrass cultivars, yet there's a gap in understanding the underlying physiological mechanisms and the impact of cold acclimation and deacclimation processes. Additionally, the influence of mowing height on carbohydrate synthesis and freeze tolerance has been reported. To address these gaps, a study utilizing turfgrass plugs from different acclimation stages was conducted in a freeze chamber. The objective of this study was to examine freeze tolerance and carbohydrate synthesis in four clonal-type bermudagrass varieties ('Tifway’, ‘Tahoma 31’, ‘Astro’, and ‘TifTuf’) under mowing heights of 0.5” and 1.5” across various cold acclimation and deacclimation stages. The plugs were subjected to soil temperatures ranging from -5°C to -12°C, with survival assessed after three weeks to determine the lethal temperature (LT50) for each condition. Rhizome carbohydrate levels at each stage were determined. The correlation between rhizome carbohydrate level and freeze tolerance was determined. The data from this study is currently being analyzed.

Soybean is a short-day plant, which means that days must be shorter than a critical value to induce flowering. Manipulating the photoperiod regime is a well-known way to shorten plant cycles in speeding breeding programs. However, the impact of the photoperiod on the quality of the produced seeds is not well understood. Here, we investigate how photoperiod affected the seed and seedling quality in soybean plants, grown in a controlled environment. Soybean (Glycine max) plants (var. S16-14801C and CZ7570LL) were grown in growth chambers with controlled temperature (27 ± 0.5˚C), CO2 (475 ± 15 µmol mol-1), humidity (70 ± 5.0%), and light (300 ± 5 µmol m-2 s-1 at table; 20% blue,10% green, 70% red). One week after germination, seedlings were exposed to different photoperiod regimes: i) 10 h (0 w at 18 h), ii) two weeks at 18 h and then 10 h (2 w at 18 h), iii) four weeks at 18 h and then 10 h (4 w at 18 h); iv) six weeks at 18 h and then 10 h (6 w at 18 h). The plants were grown in the described treatments until the R8 stage (95% brown pods), without changing the light fixture height (industry standard practice). A sample of seeds was harvested and analyzed regarding quality while other samples were placed to germinate in seed germination paper to evaluate germination rate and seedling growth for 10 days. Similar results were found for both varieties; plants of all treatments presented different heights, in which plants at 0 w at 18 h were shorter (50 cm) and 6 w at 18 h taller (180 cm). Treatments did not affect the moisture or weight of 100 seeds. Conversely, germination and seedling survival were 30% lower in seeds from plants 0 w at 18 h than in other treatments. Similar results were found for the root (13% lower in 0 w at 18 h) and shoot length (19% lower in 0 w at 18 h) of seedlings. However, the dry weight of seedlings was similar among treatments. Manipulating the photoperiod can speed up the plant cycle and is a good alternative for speed-breading programs. However, extreme photoperiods and low daily light integral can produce seeds and seedlings with lower quality that can influence the production of plants of the next generation.

In hydroponics, the pH of the nutrient solution influences the solubility and availability of essential nutrients. The optimal pH for plant nutrient uptake in many crop species is around 6.0. However, the impacts of precise pH management on plant nutrient uptake, crop yield, and the optimal pH range remain less clear. In this study, we investigated the effects of pH management range on plant nutrient uptake and the growth of hydroponic leafy vegetables. Within an indoor vertical farm, we grew lettuce (Lactuca sativa) 'Rex,' kale (Brassica oleracea var. sabellica) 'Red Russian,' and arugula (Eruca sativa) 'Astro' using deep water culture hydroponics at the air temperature of 22 °C under a photosynthetic photon flux density of 200 μmol∙m−2∙s−1 with a 24-h photoperiod. The experiment included six pH treatments: pH 6, 6±0.5, 6±1.0, 6±1.5, 6±2.0, and without pH control. Compared to managing pH at 6, maintaining pH within 6±1.0 had generally similar impacts on leaf number, leaf area, SPAD index, shoot and root fresh mass, and shoot and root dry mass in all three crops. However, when compared to managing pH at 6, maintaining pH at 6±1.5 or greater reduced leaf area (by 32-47% in lettuce, by 30-41% in kale, or by 56-65% in arugula) and shoot fresh mass (by 33-54% in lettuce, by 37-45% in kale, or by 48-64% in arugula). Furthermore, in comparison to managing pH at 6, maintaining pH at 6±1.5 or greater also decreased leaf number in lettuce by 3-5 leaves and in arugula by 13-15 leaves but increased the root fresh mass of lettuce by 26-43%. Our results suggest that maintaining pH within 6±1.0 can be effective in promoting optimal nutrient uptake and overall plant development in the context of hydroponic cultivation.

Iron is an essential micronutrient for the growth and development of both plants and humans, as it plays vital roles in processes such as protein synthesis, respiration and DNA replication. Leafy greens, vital dietary sources of iron, can be cultivated with increased bioavailable iron through hydroponics by customizing nutrient solutions. Conventionally, iron chelates like EDTA and DTPA, are used in hydroponics, but challenges persist in iron acquisition due to their pH dependency as well as quick oxidation to ferric ion which is harder to uptake by plants. Good sources of chelates that respond well to high pH values, like EDDHA, are often more expensive. Studies suggest that iron complexed with humic substances exhibits higher efficiency, though confirmation in large-scale hydroponic systems is still needed. Fulvic acids are water-soluble humic substances with lower molecular weights that hold promise as alternatives or supplements to synthetic chelates, enhancing iron uptake and stress tolerance. Hydroponic systems, such as Deep-Water Culture (DWC) or Nutrient Film Technique (NFT), impact plant growth and nutrient uptake differently based on temperature, EC, and pH. This research compared the effects of various iron chelators on lettuce and kale cultivation in DWC and NFT systems. Results indicate significant yield loss in iron-deficient kale, while iron-chelated solutions enhanced yields. The addition of fulvic acid to EDTA-chelated solutions notably improved kale yield in DWC compared to no iron and EDTA-only solutions. Leafy greens showed higher chlorophyll fluorescence (Fv/Fm ratio) and chlorophyll content in DWC compared to NFT. The results showed species-specific and system-specific responses. Notably, iron-chelated plants exhibit higher iron content correlating with increased shoot weight and chlorophyll content. The effect of fulvic acids and synthetic chelates might be synergistic, with both providing different advantages that can be complementary in hydroponic solutions. This study highlights the importance of iron management in hydroponics and the way forward for iron fortification techniques.

Biochar has long been proposed to be a substitute for peat in soilless mixes for greenhouse growing. Low levels of biochar have been shown to increase disease resistance, increase nutrient supply and uptake, and immobilize phytotoxic substances. Due to its high porosity and pH, biochar has the potential to provide an ideal habitat for mycorrhizal fungi to partner with plant roots. This study examined how various mycorrhiza sources interacted with different biochar rates to effect geraniums (Pelargonium x hortorum L. ‘Maverick Red’). Four different mycorrhizal sources were used in addition to a control containing no mycorrhiza: two commercial sources, MycoBloom and BioAg Vam-Endo, spores extracted from agricultural soils, and spores extracted from prairie soil, with four biochar rates implemented: 0, 15, 30, and 45%. Media with biochar incorporated remained saturated for longer periods after irrigation than pots filled with straight BM-7 peat-media. Prairie soil combined with 15% biochar-BM7 media formed buds and began to flower before all other treatments. Results suggest that biochar and mycorrhiza may pair well to improve potted plant growing.

Nutrient solutions play a crucial role in determining crop yield and quality, with optimized quantities offering sustainability benefits. However, there is a lack of comprehensive research regarding the optimal nutrient application quantity for various leafy green vegetables in recirculating hydroponic cultivation. To address this research gap, we proposed a project on different nutrient application quantities using the nutrient film technique (NFT) hydroponic system in a greenhouse with three replications during the fall (air temp: 24.22°C, RH: 31.2%), winter (air temp: 15.5 °C, RH: 73.3%) and early spring (air temp: 13.7 °C, RH: 72.4% ). The project focused on exploring different nutrient solution quantities of Low (76 liters), Medium (114 liters), and High (151 liters) nutrient regimens for six different leafy green vegetable species and cultivars common in Kansas including red butter lettuce (Lectuca sativa), green butter lettuce (Lectuca sativa), arugula (Eruca sativa), kale (Brassica oleracea), red malabar spinach (Basella alba), and basil (Ocimum basilicum). Our results showed that green butter lettuce and basil remained unaffected by the treatments throughout the study. Additionally, plant height, leaf count, and SPAD value for all species remained consistent across treatments and seasons. However, during the fall, the shoot fresh weight of red butter lettuce and kale increased by 7.11% and 21.1%, respectively, in the high-nutrient regimen. Moreover, the dry shoot weight of kale increased by 18.7% in the high-nutrient regimen, while the dry shoot weight of the red malabar spinach increased by 10.3% in the low-nutrient regimen. In contrast, during winter, the shoot fresh weight of red butter lettuce increased by 18.9% and 25.0%, respectively, in medium nutrient regimens compared to low and high nutrient regimens. Similarly, the shoot fresh weight of red malabar spinach increased by 15.3% and 25.0%, respectively, in low-nutrient regimens compared to medium and high-nutrient regimens. During early spring, the shoot fresh weight of red butter lettuce increased by 17.9-18.0% and that of arugula increased by 17.8% in the high-nutrient regimen, compared to low and medium nutrient regimens. In summary, the high-nutrient regimen benefited red butter lettuce and kale in fall and arugula in early spring. Conversely, during winter, the medium nutrient regimen benefited red butter lettuce, while the low nutrient regimen benefited red malabar spinach. The results from this experiment identified the optimal nutrient application quantity which helps to reduce nutrient waste for vital leafy vegetables in Kansas for different seasons and offers valuable production guidelines for local growers.

Anthropogenic climate change (ACC) will have considerable effects on plants, though the extent to which these effects are positive or negative has been controversial. For this poster, a fully factorial experiment combining water and temperature over broad ranges (10-90% soil water content under 16°C-40°C) was carried out to address three shortcomings that might help explain the contrasting effects of climate change on plants: testing only one climate variable (e.g., only water or only temperature), failure to account for nonlinear responses to climatic variables, and studying a limited number of response variables. The experiment utilized wheat as the model species and found that most dependent variables related to grain production showed the highest performance under 23-33°C and low water (

Oxygen is crucial for the growth and nutrient uptake of plant roots, especially in crops like strawberries that demand high levels of oxygen in their root zones. However, in hydroponic systems, the nutrient solution is often inadequately oxygenated. In this study, we examined the effects of supplementing dissolved oxygen (DO) into the nutrient solution on the growth of strawberry plants. Inside an indoor vertical farm, bare-root plants of strawberry ‘Albion’ and ‘Eversweet’ were grown using deep water culture hydroponics under a controlled environment of 23 °C air temperature and an 18-h photoperiod, with an extended photosynthetic photon flux density of 350 µmol∙m –2 ∙s –1 . The DO concentration of the nutrient solution was maintained at control levels (no adjustment) or supplemented using an air pump or an oxygen concentrator. The average DO concentrations in the control condition was 70%, while supplementing the nutrient solution with an air pump or an oxygen concentrator increased the average DO concentration to 85% and 100%, respectively. Supplementing with DO had minimal to no effect on the days to root of strawberry bare root plants in both cultivars. Four weeks after the DO treatments, root length, crown diameter, leaf area, and fresh mass of shoot and root were also similar in both cultivars regardless of DO concentration. The effects of supplementing DO on flowering and fruit production will also be presented.

Efficient nutrient management is the key to successful hydroponic production. However, there is a lack of comprehensive research regarding the optimal electrical conductivity (EC) levels for various leafy green vegetables in recirculating hydroponic cultivation. To address this research gap, we experimented with different EC levels using the nutrient film technique (NFT) hydroponic system in a greenhouse with three replications during the fall (air temp: 24.22°C, RH: 31.2%) winter (air temp: 15.5 °C, RH: 73.3%) and early spring (air temp: 13.7 °C, RH: 72.4%). The experiment was conducted using three different EC levels (1.2, 1.8, and 2.4 mS/cm) for six different leafy green vegetables kale (Brassica oleracea) ‘Winter bor F1’ and ‘Toscano’, swiss chard (Beta vulgaris), basil (Ocimum basilicum) ‘Prospera® Compact DMR (PL4)’ and ‘large leaf’ and red malabar spinach (Basella alba). Our results showed that, during the fall, the shoot fresh weight of the ‘Winter bor F1’ increased by 13.1 % in EC 2.4 compared to EC 1.2 and that of Swiss chard increased by 8.3-20.6% in EC 2.4 compared to EC 1.2 and 1.8 while that of ‘Prospera® Compact DMR (PL4)’ basil increased by 13.1-13.9 % in EC 1.8 compared to EC 1.2 and 2.4. In contrast during the winter, the shoot fresh weight of ‘Toscano’ kale, ‘Winter bor F1’ kale, and ‘large leaf’ basil increased by 11.2-17.8%, 18.9-20.8%, and 13.2-14.7%, respectively in EC 2.4 compared to EC 1.2 and 1.8, while that of ‘Prospera® Compact DMR (PL4)’ basil increased by 19.2 % in EC 1.2 compared to the EC 2.4. However, during the early spring, only the shoot fresh weight of ‘Winter bor F1’ kale in EC 1.8 was increased by 10.0 % compared to EC 1.2, while the plant height and fresh shoot weight of large leaf basil was increased slightly by 3.1-5.6% in EC 2.4 compared to EC 1.2. In summary, this experience suggested that ’Winter bor F1’ kale performed best in EC 2.4 during the fall and winter seasons but grew best in EC 1.8 during the early spring. In addition, the 2.4 mS/cm proved the optimal EC level for Swiss chard during the fall, ‘Toscano’ kale during the winter, and ‘large leaf’ basil during the spring. The results from this experiment identify optimal EC levels of vital leafy vegetables in Kansas for different seasons, aiding Kansas growers in reducing nutrient waste and enhancing leafy vegetable production.