The objectives were to 1) compare growth and yield of different ginger (Zingiber officinale) and turmeric (Curcuma longa) propagules grown under two photoperiods (Expt. 1); and 2) evaluate whether their growing season could be extended with night interruption lighting (NI) during the winter (Expt. 2). In Expt. 1, propagules included 1) micropropagated tissue culture (TC) transplants, 2) second-generation rhizomes harvested from TC transplants (2GR), and 3) seed rhizomes (R). Plants received natural short days (SDs) or NI providing a total photon flux density (TPFD) of 1.3 µmol·m−2·s−1. Providing NI increased number of new tillers or leaves per plant, rhizome yield (i.e., rhizome fresh weight), and dry mass partitioning to rhizomes in both species. There was no clear trend on SPAD index in response to photoperiod or propagative material. Although TC-derived plants produced more tillers or leaves per plant, 2GR ginger and R turmeric produced a higher rhizome yield. In Expt. 2, seed rhizomes of ginger and turmeric were grown under five treatments with different photoperiods and/or production periods: 1) 20 weeks with NI (20NI), 2) 24 weeks with NI (24NI), 3) 28 weeks with NI (28NI), 4) 14 weeks with NI + 10 weeks under natural SDs (24NISD), and 5) 14 weeks with NI + 14 weeks under natural SDs (28NISD). NI provided a TPFD of 4.5 µmol·m−2·s−1. Lengthening the production period and providing NI increased rhizome yield and crude fiber content in both species. SPAD index decreased when plants were exposed to natural SDs at the end of the production period (NISD treatments). Results demonstrate the potential to overcome winter dormancy of ginger and turmeric plants with NI, enabling higher rhizome yield under natural SDs.
Sofia Flores, Marlon Retana-Cordero, Paul R. Fisher, Rosanna Freyre, and Celina Gómez
Michael P. Dzakovich, Celina Gómez, Mario G. Ferruzzi, and Cary A. Mitchell
In addition to photosynthesis, light is a critical mediator of secondary metabolism in plants, signaling the production of potentially health-promoting phytochemicals and regulating the emission of volatile organic compounds (VOCs) that can alter the sensory perception of a tomato. Light-emitting diodes (LEDs) are a viable way to test the effects of individual wavebands of light and are being quickly adopted by the greenhouse tomato industry. However, studies characterizing the effects of specific wavelengths of light or supplemental lighting on phytochemical content in general are lacking. We hypothesized that enriching the amount of supplemental blue and/or red light that tomatoes receive would positively affect the amount of carotenoids and phenolic compounds that accumulate in tomato fruits through cryptochrome and/or phytochrome-dependent signaling pathways. To test this hypothesis, we compared the chemical and sensory characteristics of tomatoes grown with overhead high-pressure sodium (OH-HPS) lamps to those grown with intracanopy (IC)-LEDs emitting different ratios of red, blue, and far red light. Tomatoes were profiled for total soluble solids, titratable acidity, ascorbic acid content, pH, total phenolics, and prominent flavonoids and carotenoids. Our studies indicated that greenhouse tomato fruit quality was only marginally affected by supplemental light treatments. Moreover, consumer sensory panel data indicated that tomatoes grown under different lighting treatments were comparable across the lighting treatments tested. Our research suggests that the dynamic light environment inherent to greenhouse production systems may nullify the effects of wavelengths of light used in our studies on specific aspects of fruit secondary metabolism.
Elisa Solis-Toapanta, Paul R. Fisher, and Celina Gómez
Interest in hydroponic home gardening has increased in recent years. However, research is lacking on minimum inputs required to consistently produce fresh produce using small-scale hydroponic systems for noncommercial purposes. Our objectives were to 1) evaluate the effect of biweekly nutrient solution replacements (W) vs. biweekly fertilizer addition without a nutrient solution replacement (W/O) on final growth, yield, and nutrient uptake of hydroponic tomato (Solanum lycopersicum) plants grown in a greenhouse, and 2) characterize growth over time in a greenhouse or an indoor environment using W. For each environment, ‘Bush Goliath’ tomato plants were grown for 12 weeks in 6.5-gal hydroponic systems. The experiment was replicated twice over time. In the greenhouse, plants were exposed to the following day/night temperature, relative humidity (RH), and daily light integral (DLI) in 2018 (mean ± SD): 31 ± 6/22 ± 2 °C, 67% ± 8%, and 32.4 ± 7 mol·m‒2·d‒1; and in 2019: 28 ± 6/22 ± 3 °C, 68% ± 5%, and 27.7 ± 6 mol·m‒2·d‒1. For both experimental runs indoors, the day/night temperature, RH, and DLI were 21 ± 2 °C, 60% ± 4%, and 20 ± 2 mol·m‒2·d‒1 provided by broadband white light-emitting diode lamps. The W/O treatment resulted in a higher-than-desired electrical conductivity (EC) and total nutrient concentration by the end of the experiment. In addition, compared with the W treatment, W/O resulted in less leaf area, more shoot growth, less water uptake, and similar fruit number—but increased blossom-end-rot incidence, delayed fruit ripening, and lower fruit fresh weight. Nonetheless, the final concentration of all nutrients was almost completely depleted at week 12 under W, suggesting that the applied fertilizer concentration could be increased as fruiting occurs. Surprisingly, shoot biomass, leaf area, and leaf number followed a linear trend over time in both environments. Nonetheless, given the higher DLI and temperature, greenhouse-grown plants produced 4 to 5 kg more of fruit than those grown indoors, but fruit from plants grown indoors were unaffected by blossom-end-rot. Our findings indicate that recommendations for nutrient solution management strategies should consider specific crop needs, growing environments, and production goals by home gardeners.
Kristin E. Gibson, Alexa J. Lamm, Fallys Masambuka-Kanchewa, Paul R. Fisher, and Celina Gómez
There are economic and knowledge-based challenges that must be addressed for indoor farms to be viable in the United States despite their potential benefits. A mixed-methods approach was used to identify the needs of specialty crop growers and stakeholders interested in or currently using indoor propagation environments to grow seedlings, cuttings, and tissue-cultured plants. An online survey evaluated specialty crop growers’ current use of indoor plant propagation environments and their needs related to indoor plant propagation. A focus group was then conducted to further understand the needs for indoor plant propagation by stakeholders. Industry participants were largely motivated to adopt indoor propagation environments to reduce crop losses (“shrinkage”), increase productivity per unit of land area, ensure faster germination or rooting, improve plant quality, and profit from anticipated economic benefits. Research and education priority areas identified by stakeholders included economic costs and benefits (including capital investment and energy costs), improved crop quality, production time, uniformity, reduced shrinkage, and strategies to improve light management indoors. Based on the results, research efforts must determine and prioritize the most important economic considerations and production advantages to fill important gaps in knowledge about indoor plant propagation.
Celina Gómez, Christopher J. Currey, Ryan W. Dickson, Hye-Ji Kim, Ricardo Hernández, Nadia C. Sabeh, Rosa E. Raudales, Robin G. Brumfield, Angela Laury-Shaw, Adam K. Wilke, Roberto G. Lopez, and Stephanie E. Burnett
The recent increased market demand for locally grown produce is generating interest in the application of techniques developed for controlled environment agriculture (CEA) to urban agriculture (UA). Controlled environments have great potential to revolutionize urban food systems, as they offer unique opportunities for year-round production, optimizing resource-use efficiency, and for helping to overcome significant challenges associated with the high costs of production in urban settings. For urban growers to benefit from CEA, results from studies evaluating the application of controlled environments for commercial food production should be considered. This review includes a discussion of current and potential applications of CEA for UA, references discussing appropriate methods for selecting and controlling the physical plant production environment, resource management strategies, considerations to improve economic viability, opportunities to address food safety concerns, and the potential social benefits from applying CEA techniques to UA. Author’s viewpoints about the future of CEA for urban food production are presented at the end of this review.