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Steven H. Schwartzkopf, Diane Dudzinski, and R. Sjhon Minners

Abstract

Two methods of removing bacteria from hydroponic nutrient solution [ultraviolet (UV) radiation and submicronic filter] were evaluated for efficiency and for their effects on lettuce (Lactuca sativa L.) production. Both methods were effective in removing bacteria; but, at high intensity, the ultraviolet sterilizer significantly inhibited the production of plants grown in the treated solution. Bacterial removal by lower intensity UV or a submicronic filter seemed to promote plant growth slightly, but showed no consistent, statistically significant effect.

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Matthew J. Koch and Stacy A. Bonos

popular methods for salinity screening is growing turfgrass plants in a hydroponic saline solution ( Dai et al., 2009 ; Lee et al., 2004 ; Marcum, 2000 ; Marcum and Kopec, 1997 ; Marcum and Murdoch, 1994 ; Pessarakli and Kopec, 2008 , 2009 ; Qian et

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Richard V. Tyson, Danielle D. Treadwell, and Eric H. Simonne

Aquaponics ( Diver and Rinehart, 2010 ; Nelson, 2007 ) is an integrated system that links hydroponic production ( Jensen, 1997 ; Resh, 2004 ) with recirculating aquaculture ( Timmons et al., 2002 ). The advantages of linking crop production and

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Qi Zhang, Sheng Wang, and Kevin Rue

agar medium. Germination rate and seedling growth (blade length and tissue weight) of perennial ryegrass, kentucky bluegrass, and tall fescue cultivars under saline conditions were evaluated in hydroponic systems ( Horst and Beadle, 1984 ; Horst and

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Andrew C. Schuerger and Christopher S. Brown

Plants were grown under light-emitting diode (LED) arrays with various spectra to determine the effects of light quality on the development of diseases caused by tomato mosaic virus (ToMV) on pepper (Capsicum annuum L.), powdery mildew [Sphaerotheca fuliginea (Schlectend:Fr.) Pollaci] on cucumber (Cucumis sativus L.), and bacterial wilt (Pseudomonas solanacearum Smith) on tomato (Lycopersicon esculentum Mill.). One LED (660) array supplied 99% red light at 660 nm (25 nm bandwidth at half-peak height) and 1% far-red light between 700 to 800 nm. A second LED (660/735) array supplied 83% red light at 660 nm and 17% far-red light at 735 nm (25 nm bandwidth at half-peak height). A third LED (660/BF) array supplied 98% red light at 660 nm, 1% blue light (BF) between 350 to 550 nm, and 1% far-red light between 700 to 800 nm. Control plants were grown under broad-spectrum metal halide (MH) lamps. Plants were grown at a mean photon flux (300 to 800 nm) of 330 μmol·m-2·s-1 under a 12-h day/night photoperiod. Spectral quality affected each pathosystem differently. In the ToMV/pepper pathosystem, disease symptoms developed slower and were less severe in plants grown under light sources that contained blue and UV-A wavelengths (MH and 660/BF treatments) compared to plants grown under light sources that lacked blue and UV-A wavelengths (660 and 660/735 LED arrays). In contrast, the number of colonies per leaf was highest and the mean colony diameters of S. fuliginea on cucumber plants were largest on leaves grown under the MH lamp (highest amount of blue and UV-A light) and least on leaves grown under the 660 LED array (no blue or UV-A light). The addition of far-red irradiation to the primary light source in the 660/735 LED array increased the colony counts per leaf in the S. fuliginea/ cucumber pathosystem compared to the red-only (660) LED array. In the P. solanacearum/ tomato pathosystem, disease symptoms were less severe in plants grown under the 660 LED array, but the effects of spectral quality on disease development when other wavelengths were included in the light source (MH-, 660/BF-, and 660/735-grown plants) were equivocal. These results demonstrate that spectral quality may be useful as a component of an integrated pest management program for future space-based controlled ecological life support systems.

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Kellie J. Walters and Christopher J. Currey

increased ( Wolf et al., 2005 ), year round production in colder climates is only possible in controlled environments. Research has been conducted on field production of basil ( Sifola and Barbieri, 2006 ), but there are areas of hydroponic greenhouse basil

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Chieri Kubota, Mark Kroggel, Mohammad Torabi, Katherine A. Dietrich, Hyun-Jin Kim, Jorge Fonseca, and Cynthia A. Thomson

potential in the root zone. Based on this understanding, growing tomato plants hydroponically using nutrient solution with high EC has been commercially practiced worldwide, yet to a limited extent in North America ( Buck et al., 2008 ). Lycopene is an

Open access

Alexander Miller, Petrus Langenhoven, and Krishna Nemali

Hydroponics is a common method of growing crops in controlled environment agriculture systems ( Jensen, 1999 ). Leafy greens like lettuce are a popular choice for hydroponic production ( Curran, 2018 ). Lettuce can potentially fetch a higher price

Open access

Sofía Gómez and Celina Gómez

agriculture ( Kozai et al., 2022 ). In recent reviews, Rouphael and Colla (2020 ) and Ertani et al. (2021 ) described how biostimulants can help improve various plant processes in the field or using hydroponic systems in high-tunnels or greenhouses. However

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Jinghua Guo, Yan Yan, Lingdi Dong, Yonggang Jiao, Haizheng Xiong, Linqi Shi, Yu Tian, Yubo Yang, and Ainong Shi

(Fe), calcium, folate, and fiber; they are also low in calories and sodium; and all varieties are free of fat and cholesterol ( Jones, 1982 ). Compared to hydroponic fruit, green-leaf vegetables are easy to plant and their production is low in cost