Red and blue light are traditionally believed to have a higher quantum yield of CO 2 assimilation ( QY , moles assimilated per mole photons) than green light, because is absorbed less efficiently. However, its lower absorptance, can penetrate deeper excite chlorophyll in leaves. We hypothesized that, at high photosynthetic photon flux density PPFD ), may achieve net rate A n ) red or more uniform absorption throughtout To test the interactive effects spectrum on photosynthesis, we measured...

ABSTRACT The possibility of uptake salmonellae by roots hydroponically grown tomato plants was investigated. Within 1 day exposure plant to Hoagland nutrient solution containing 4.46 4.65 log 10 CFU salmonellae/ml, the sizes pathogen populations were 3.01 CFU/g hypocotyls and cotyledons 3.40 stems for with intact root systems (control) 2.55 from which portions had been removed. A population ≥3.38 hypocotyls-cotyledons, stems, leaves 9 days detected regardless condition. Additional studies...

Linear electron transport depends on balanced excitation of photosystem I and II. Far‐red light preferentially excites (PSI) can enhance the photosynthetic efficiency when combined with that over‐excites II (PSII). The different wavelengths far‐red exciting PSI was quantified by measuring change in quantum yield PSII (Φ ) lettuce ( Lactuca sativa under red/blue narrowband added (from 678 to 752 nm, obtained using laser diodes). Φ increased increasing from 703 indicating longer within this...

Light-emitting diodes allow for the application of specific wavelengths light to induce various morphological and physiological responses. In lettuce (Lactuca sativa), far-red (700-800 nm) is integral initiating shade responses which can increase plant growth. first two studies, plants were grown with a similar photosynthetic photon flux density (PPFD) but different intensities light. The second study used perpendicular gradients PPFD, allowing examination interactive effects. gradient...

OPINION article Front. Plant Sci., 22 June 2021 | https://doi.org/10.3389/fpls.2021.693445

Summary The current definition of photosynthetically active radiation includes only photons from 400 up to 700 nm, despite evidence the synergistic interaction between far‐red and shorter‐wavelength photons. synergy has not been studied in sunlight under natural conditions. We used a filter remove above nm quantify effects on photosynthesis diverse species full sun, medium light intensity vegetation shade. Far‐red (701 750 nm) are efficiently for photosynthesis. This is especially important...

The use of sensors can provide quantitative information to help guide and automate the decision-making process for irrigation. This article provides an overview most common that be used this purpose. Such include those are commonly weather stations as well monitor water status soil or substrate, troubleshoot irrigation systems. Although collecting data with is relatively easy, only useful if correctly limitations understood. Optimizing value collected requires selecting best sensor(s) a...

Light recommendations for horticultural crops often focus on the optimal daily light integral (DLI) without regard to how that is delivered throughout each day. Because photosynthesis more efficient at lower photosynthetic photon flux density (PPFD), we hypothesized longer photoperiods with PPFD results in faster growth than shorter higher and same DLI. We quantified effect of different photoperiods, all providing DLI, two leafy greens. Mizuna (Brassica rapa var. japonica) lettuce (Lactuca...

Anthocyanins provide blue, red, and purple color to fruits, vegetables, flowers. Due their benefits for human health aesthetic appeal, anthocyanin content in crops affects consumer preference. Rapid, low-cost, non-destructive phenotyping of anthocyanins is not well developed. Here, we introduce the normalized difference index (NDAI), which based on optical properties anthocyanins: high absorptance green low red part spectrum. NDAI determined as (Ired - Igreen)/(Ired + Igreen), where I pixel...

Gaura lindheimeri Engelm. & Gray ‘Siskiyou Pink’ (gaura) and Phlox paniculata L. ‘David’ (garden phlox) were grown for 5 weeks in substrates irrigated at volumetric water contents (Θ) of 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, or 0.45 m 3 ·m −3 using a capacitance sensor-controlled irrigation system. Volumetric the substrate measured by sensors controlling correlated with measurements separate handheld meter ( r 2 = 0.83) content set points throughout study > 0.98). Only 3.8 (at an...

ABSTRACT C 3 plants dominate many landscapes and are critically important for ecosystem water cycling. At night, plant losses can include transpiration (E night ) from the canopy hydraulic redistribution (HR) roots. We tested whether E limits magnitude of HR in a greenhouse study using Artemisia tridentata , Helianthus anomalus Quercus laevis . Plants were grown with their roots split between two compartments. was initiated by briefly withholding all water, followed watering only one rooting...

Water quality and quantity are increasingly important concerns for agricultural producers have been recognized by governmental nongovernmental agencies as focus areas future regulatory efforts. In horticultural systems, especially container production of ornamentals, irrigation management is challenging. This primarily due to the limited volume water available container-grown plants after an event resultant need frequently irrigate maintain adequate soil moisture levels without causing...

Wireless sensor networks (WSNs) transmit data and control signals over long distances without the need for expensive infrastructure, allowing WSNs to add value existing irrigation systems since they provide grower with direct feedback on water needs of crop. We implemented in nine commercial horticulture operations. an overview integration sensors hardware software form that can monitor applications based one two approaches: 1) “set-point control” substrate moisture measurements or 2)...

Supplemental lighting in greenhouses is often needed for year-round production of high-quality crops. However, the electricity supplemental can account a substantial part overall costs. Our objective was to develop more efficient control methods lighting, taking advantage dimmability light-emitting diode (LED) grow lights. We compared 14 hours per day full power LED two other treatments: 1) turning LEDs on, at power, only when ambient photosynthetic photon flux ( PPF ) dropped below specific...

Substrate volumetric water content (VWC) is a useful measurement for automated irrigation systems. We have previously developed controllers that use capacitance sensors and dataloggers to supply plants with on-demand irrigation. However, the accompanying software used build program those make these systems expensive. Relatively new, low-cost open-source microcontrollers provide an alternative way sensor-based both agricultural domestic applications. designed built system using...

Subirrigation is a greenhouse irrigation method that relies on capillary action to provide plants with water and nutrients from below their containers. The first documented subirrigation system was described in 1895, several variations the basic design were used for research purposes before modern ebb-and-flow type systems emerged 1974. Most apply fertilizer solution waterproof bench or section, allowing substrate absorb through holes bottom of Because there little no leaching, typically...

Supplemental lighting can improve the growth of greenhouse crops, but electricity required for supplemental be a significant expense growers. Lighting control strategies that use dimmability light-emitting diodes (LEDs) have potential to decrease this cost. In our experiments, we tested hypothesis providing ‘Little Gem’ lettuce ( Lactuca sativa ) plants with same daily amount light, spread out over longer photoperiod and at lower average photosynthetic photon flux densities PPFD s), would...

Controlled environment crop production recommendations often use the daily light integral (DLI) to quantify requirements of specific crops. Sole-source electric lighting, used in plant factories, and supplemental greenhouses, may be required attain a DLI. Electric lighting is wasteful if not provided way that promotes efficient photochemistry. The quantum yield photosystem II (Φ

Vertical farming is increasingly popular due to high yields obtained from a small land area. However, the energy cost associated with lighting of vertical farms high. To reduce this cost, more efficient (biomass/energy use) crops are required. understand how efficiently use light produce biomass, we determined morphological and physiological differences between mizuna (Brassica rapa var. japonica) lettuce (Lactuca sativa ‘Green Salad Bowl’). do so, measured projected canopy size (PCS,...

Acidic electrolyzed oxidizing (EO) water, generated by electrolysis of a dilute salt solution, recently gained attention in the food industry as nonthermal method for microbial inactivation. Our objective was to determine if EO water has potential control foliar diseases greenhouses. Test fungi suspended distilled were combined with (1:9 water:EO water) various time periods, neutralized, and germination assessed after 24 h. Germination all 22 fungal species tested significantly reduced or...