Plant growth and development depends on essential macronutrients such as nitrogen (N), phosphorus (P), and potassium (K), and deficiencies in these nutrients result in significant physiological and morphological changes. Leaf biochemical and biophysical properties influence light absorption and reflectance across various wavelengths, providing insights into canopy health. Advancements in high-throughput (HT) digital phenotyping technologies, including high-resolution scanning and multispectral imaging, have improved plant health assessment and monitoring. The TraitFinder, a digital phenotyping system developed by Phenospex, is equipped with two PlantEye-600 multispectral 3D laser scanners that generate three-dimensional plant models while capturing multispectral data. The system directs light in green (G), blue (B), red (R), and near-infrared (NIR) wavelengths onto the plant canopy and captures the reflected signals, which are then used to compute vegetation indices for plant health evaluation. This study utilized the TraitFinder system to determine reference values for vegetation indices associated with healthy plants and those deficient in N, P, and K. Four ornamental species—coleus (Solenostemon scutellarioides), marigold (Tagetes patula), petunia (Petunia × hybrida), and celosia (Celosia plumosa)—were evaluated over time. The experiment followed a randomized complete block design with eight replications and four nutrient treatments: a complete Hoagland’s solution and three modified versions, each lacking one macronutrient (N, P, or K). Morphological traits, such as biomass, showed reduced plant growth under nutrient-deficient conditions. Spectral data revealed common trends in nutrient-deficient plants, including decreased Green Leaf Index (GLI) and Normalized Difference Vegetation Index (NDVI) and increased Normalized Pigment Chlorophyll Ratio Index (NPCI) and Plant Senescence Reflectance Index (PSRI) compared to controls. In healthy plants, GLI ranged from 0.2 to 0.35, NDVI from 0.4 to 0.75, NPCI from 0.10 to 0.45, and PSRI from 0.07 to 0.25. However, species-specific responses to nutrient deficiencies were also observed. This study highlights the distinct morphological and physiological responses of ornamental species to macronutrient deficiencies and demonstrates the effectiveness of digital phenotyping using the TraitFinder system for tracking plant health over time. The findings emphasize the potential of HT digital phenotyping which could enhance ornamental crop management.
Easter lilies (Lilium longiflorum) cultivated in the greenhouse industry are often treated with plant growth regulators (PGRs) to control their height by reducing stem length. A greenhouse study was conducted to examine the effects of uniconazole “Sumagic” on the growth of a new cultivar of Easter lilies ‘White Spring’. Treatments consisted of five bulb sizes based on circumference (12/14, 14/16, 16/18, 18/20, 20/22 cm) and uniconazole rates of 0, 2.5, and 5.0 mg•liter-1 with eight replications. Data collection consisted of stem height measured weekly, days until anthesis, number of flowers, and phytotoxicity rating. The results of the study showed a relationship between the uniconazole treatments and plant height, control plants had a greater average height (57.8 cm) than the bulbs soaked in 2.5 and 5.0 mg•liter-1 uniconazole, (33.5 cm) and (23.8 cm), respectively. Plant heights were also influenced by bulb size as they increased in height with increase in bulb circumference. The average number of days until anthesis increased with smaller bulb circumference, as anthesis was delayed. Days until anthesis were also affected by the uniconazole treatments, the bulbs treated with 2.5 and 5.0 mg•liter-1 solutions took approximately 6 and 8 days longer, respectively. Phototoxicity effects displayed as chlorosis on leaf tips and margins occurred in both the 2.5 and 5.0 mg•liter-1 solutions with symptoms more prominent in larger bulb sizes.
Soil pH shapes rhizosphere microbial structure and diversity, influencing nutrient cycling, plant growth, and ecosystem health. However, the effects of pH on the microbiome in greenhouse-grown ornamental plants in peat-based soilless substrates are less well understood. This study examined the impact of substrate pH and plant species on rhizosphere bacterial communities to see how the interaction of these factors influenced microbial diversity. A two-factor experiment with substrate pH (4.5, 5.5, 6.2, and 7) and plant species (geranium, marigold, petunia, and tomato) was conducted in a greenhouse with six replicates per treatment (n=6) in a random complete block design. Substrate-only controls were included at each pH level to evaluate plant species influence on the bacterial community. The peat-based substrate pH was adjusted with dolomitic limestone. Plants were fertilized at each irrigation with 100 µg·g-1 N from 15-5-15-Ca-Mg fertilizer. After eight weeks of growth, the ornamental plants were fully flowering, and the tomato plants were beginning to bud. At that time, plant morphology and vegetative indices were evaluated by 3D image analysis, vegetive tissue and substrate leachate were evaluated for nutrient content, and rhizosphere samples were collected to evaluate bacterial composition and diversity by 16S amplicon sequencing. Plant species differentially modified the substrate pH from the starting levels. Geranium and marigold acidified the substrate, tomato tended to increase substrate pH, and petunia maintained pH close to the initial values. Shannon diversity indices indicated that bacterial diversity varied across the pH and plant species treatments. At pH 4.5, geranium, marigold, and tomato plants reduced the diversity relative to the no plant control. Geranium and tomato plants also reduced diversity at pH 5.5, while petunia plants at 5.5 exhibited the highest diversity across all plant species (p=0.0159). Beta diversity analysis identified pH as the dominant factor explaining 53.7% in Bray-Curtis dissimilarity and 68.5% in the weighted UniFrac distance metrics (both p
