Search Results (4)

Research on young trees’ adaptation to shade has predominantly focused on leaf-level responses, overlooking critical structural and functional adaptations in branch systems. In this study, we address this gap by investigating hierarchical branch morphology–physiology integration in 20-year-old Pinus koraiensis specimens across four distinct light conditions classified by photosynthetic photon flux density (PPFD): three in the understory (low light, LL: 0–25 μmol/m²/s; moderate light, ML: 25–50 μmol/m²/s; and high levels of light, HL: 50–100 μmol/m²/s) and one under full light as a control (FL: 1300–1700 μmol/m²/s). We measured branch base diameter, length, and angle as well as chlorophyll and NSCs content in branches and needles. Branch base diameter and length were more than 1.5-fold higher in the FL Korean pine trees compared to the understory-grown ones, while the branching angle and ratio in the LL Korean pine trees were more than two times greater than those in the FL trees. As light levels increased, Chlorophyll a and b and total chlorophyll (Chla, Chlb, and Chl) concentrations in the needles all significantly decreased. Starch, glucose, and NSC (Starch + Soluble Sugars) concentrations in both needles and branches were the highest in the trees under FL and lowest under ML (except for soluble sugars in branches). Understory young P. koraiensis trees morphologically and physiologically adapt to limited light conditions, growing to be more horizontal, synthesizing more chlorophyll in needles, and attempting to increase their light-foraging ability. We recommend gradually expanding growing spaces to increase light availability for 20-year-old Korean pine trees grown under canopy level. Full article

Photosynthetically active radiation (PAR) is crucial for plant growth, influencing photosynthesis efficiency and crop yield. The increasing adoption of controlled-environment agriculture (CEA) necessitates precise PAR monitoring. The high cost of commercial PAR sensors, however, limits their accessibility and widespread use, creating a growing need for a low-cost alternative capable of reliable deployment in diverse agricultural environments. Building on recent advancements in PAR sensing using multi-channel spectral sensors such as the AS7341 and AS7265, this study develops the electronics for an AS7341-based, open-source, cost-effective (~USD 50) PAR sensor validated across a broad PPFD range and conditions, ensuring reliability and ease of replication. It uses a relatively simple multi-linear regression that offers real-time applications without energy intensive machine learning. The developed sensor is calibrated against the industry-standard Apogee SQ-500SS PAR sensor in four distinct farming environments: (i) horizontal grow lights, (ii) vertical agrotunnel lighting, (iii) agrivoltaics, and (iv) in greenhouses. A mean error ranging from 1 to 5% indicates its suitability for controlled environment farming and continuous data logging. The open-source hardware design and systematic installation guidelines enable users to replicate, calibrate, and integrate the sensor with minimal background in electronics and optics. Full article

Plant factories with artificial lighting (PFALs), with well-insulated and airtight structures, enable the production of large quantities of high-quality plants year-round while achieving high resource use efficiency. However, despite the controlled environment in PFALs, variations in plant individuals have been found, which affect productivity in PFAL operations. Plant phenotyping plays a crucial role in understanding how the surrounding microenvironment affects variations in plant phenotypes. In the current study, a modular phenotyping system for seedling production was developed, focusing on practicality and scalability in commercial PFALs. Experiments on seedlings, which strongly affect productivity, were conducted to obtain cotyledon unfolding time and the time series projected area of cotyledons and true leaves of individual seedlings of romaine lettuce (Lactuca sativa L. var. longifolia), using RGB images. This was also undertaken to analyze how the surrounding microenvironment of photosynthetic photon flux densities and nutrients affect growth variations for plant cohort research. In agreement with the actual measurements, variations in seedling growth were identified even under similar microenvironments. Furthermore, the results demonstrated larger variations in seedlings with higher relative growth. Aiming for simplified interactions of phenotypes with the microenvironment, management, and genotype, seedling selection and breeding with plant production in PFALs may enable plant uniformity and higher productivity. Full article

Aquaponic facilities allow the joint production of fish and plants in a reduced space. This hydroponic technique, combined with vertical farming, is not well studied. The main objective of this work was to compare basil production between horizontal and vertical decoupled aquaponic systems and assess the utilization of supplemental lighting in a greenhouse environment. Six independent vertical racks were arranged with hydroponic trays at three heights. Three racks were affixed with LED lighting on the lowest levels and three with supplemental lighting on the intermediate level. Immediately adjacent to the vertical systems, two independent horizontal systems containing three trays were constructed to compare basil production. After 35 days of growth post transplanting, the total production per tray and weight, height, number of leaves, and nodes of 20 selected plants per tray were determined. Records of the intensity of illumination photosynthetic photon flux density (PPFD)) were recorded at dawn (8:00), noon (12:00), and dusk (18:00) at randomly predetermined positions associated with the 20 selected plants per tray. The total basil production in the experiment was 58.79 kg, with an average production per unit area of 2.43 and 0.94 kg m⁻² for vertical and horizontal systems, respectively. Productivity per unit area in the vertical systems was 160% greater than in horizontal systems. A significant effect of lighting, the height of the tray, and plant position inside the tray was found on plant growth parameters. Optimization of light source distribution and tray orientation can enhance the productive performance in vertical aquaponic systems. Electricity cost associated with supplemental lighting per kg of production increment was 21.84 and 12.25 $ kg⁻¹ for the bottom and intermediate levels of the vertical system, respectively, the latter being economically the most profitable. Full article