Carbon dioxide (CO₂) concentration is reported to be the most important climate variable in greenhouse production with its effect on plant photosynthetic assimilation. A greenhouse study was conducted using a nutrient film technique (NFT) system to quantify the effect of two different levels of CO₂ (supplemented at an average of 800 ppm and ambient at ~410 ppm) on growth and nutritional quality of basil (Ocimum basilicum L.) ‘Cardinal’, lettuce (Lactuca sativa L.) ‘Auvona’, and Swiss chard (Beta vulgaris L.) ‘Magenta Sunset’ cultivars. Two identical greenhouses were used: one with CO₂ supplementation and the other serving as the control with an ambient CO₂ concentration. The results indicate that supplemented CO₂ could significantly increase the height and width of hydroponically grown leafy greens. Supplemented CO₂ increased the fresh weight of basil ‘Cardinal’, lettuce ‘Auvona’, and Swiss chard ‘Magenta Sunset’ by 29%, 24.7%, and 39.5%, respectively, and dry weight by 34.4%, 21.4%, and 40.1%, respectively. These results correspond to a significant reduction in Soil Plant Analysis Development (SPAD) and atLEAF values, which represent a decrease in leaf chlorophyll content under supplemented CO₂ conditions. Chlorophyll, nitrogen (N), phosphorus (P), and magnesium (Mg) concentrations were generally lower in plants grown in supplemented CO₂ conditions, but the results were not consistent for each species. Supplemented CO₂ reduced tissue N concentration for basil ‘Cardinal’ and lettuce ‘Auvona’ but not Swiss chard, while Mg concentration was reduced in supplemented CO₂ for Swiss chard ‘Magenta Sunset’ only. In contrast, Fe concentration was increased under supplemented CO₂ for basil ‘Cardinal’ only. These findings suggest CO₂ supplementation could increase yield of leafy greens grown with hydroponics and have varying impact on different mineral concentrations among species.

Shade and drought commonly occur together in turfgrass systems due to competition with trees for light and soil water. Two greenhouse studies were conducted to evaluate the effects of combined drought and shade stress on bermudagrass [Cynodon dactylon (L.) Pers.] and hybrid bermudagrass [C. dactylon (L.) Pers. × C. transvaalensis Burtt Davy] physiology. ‘Latitude 36 Turf Bermudagrass’ (Latitude 36^TM) hybrid bermudagrass and ‘Riley's Super Sport’ (Celebration^®) bermudagrass were selected for Experiment 1, while ‘Patriot’ hybrid bermudagrass was added as a shade‐sensitive cultivar in Experiment 2. Washed plugs of each cultivar were planted in growth tubes (10 cm diameter by 46 cm length polyvinyl chloride pipe with a flat bottom cap) filled with a 1:1 topsoil/sand root‐zone. Each experiment was conducted as a completely random design with two factors (cultivar and irrigation) repeated under two light environments. Light environment was defined as either adequate light (20.8–26.8 mol m^–2 d^–1) or low light (9.7–10.1 mol m^–2 d^–1) conditions. Irrigation was applied by hand to achieve either 100% (well‐watered) or 50% (drought) replacement of evapotranspiration (ET). Under drought conditions, low light resulted in a gradual decline in ET rate, whereas adequate light showed a sharp decline in ET rate over time. Under adequate light, Patriot consumed the most water among cultivars for either well‐watered or drought conditions. In contrast, Patriot (well‐watered) had the lowest water use in the low light environment, suggesting shade tolerance could potentially influence drought response under low light environments.

Objective methods of estimating green coverage using digital image analysis have been used increasingly by turfgrass scientists. The objective of our research was to evaluate the effectiveness of Canopeo, a relatively new smartphone application, for estimating green coverage of bermudagrass ( Cynodon dactylon ) emerging from winter dormancy, with or without colorants. A field study was conducted on a research ‘U3’ bermudagrass fairway in Stillwater, OK, during Spring 2019 and 2020. The experiment was conducted as a randomized complete block design with three colorant treatments: Endurant Fairway (FW), Endurant Perennial Ryegrass (PR), and an untreated control. Green coverage of the turfgrass canopy was determined weekly from mid-March to early May using a digital camera and ImageJ software, and a smartphone and the Canopeo application. Green coverage estimates from Canopeo correlated strongly ( r = 0.91) with those from ImageJ when no colorants were applied. Correlation between Canopeo and ImageJ was diminished under plots treated with colorants. Canopeo is an effective tool for estimating green coverage of living turfgrasses, but additional calibration may be required for acceptable performance when evaluating greenness of colorant-treated turfgrasses.